PeterJ. Gore Willse, HSB Industrial Risk Insurers, CT [I]
(Alt. to T. E. Schumann)
Michael L. Wolf, Greenheck, WI [M]
(Alt. to D. Rammien)
Report of the Committee on
Smoke Management Systems
James A. Milke, Chair
University of Maryland, MD [SE]
Nonvoting
Bent A. Borresen, Techno Consultant, Norway
(Air. to C. N. Madsen)
E. G. Butcher, Fire Check Consultants, England
(Alt. to A~ (3. Parnell)
John H. Klote, John H. Klote, Inc., VA [SE]
Christian Norgaard Madsen, Techno Consultant, Norway
Alan G. Parnell, Fire Check Consultants, England
Daniel L. Arnold, RolfJensen & Assoc., Inc., GA [SE]
Donald W. Belles, Koffel Assoc., Inc., TN [M]
Rep. American Architectural Mfrs. Assn.
Jack B. Bucldey, Houston, TX [SE]
Paul J. Carrafa, Building Inspection Underwriters, Inc., PA [E]
Elmer F. Chapman, Fire Dept. New York, NY [E]
Michael Earl Dillon, Dillon Consulting Engr, Inc., CA [SE]
S. E. Egesdal, Honeywell Inc., MN [M]
Rep. Nat'l Electrical Mfrs. Assn.
Douglas H. Evans; Clark County Building Dept., NV [E]
Gunnar Heskestad, Factory Mutual Research Corp., MA [I]
Winfield T. Irwin, Irwin Services, PA [M]
Rep. North American Insulation Mfrs. Assn.
Daniel J. Kaiser, Underwriters Laboratories Inc., IL [RT]
Gary D. Lougheed, Nat'l Research Council of Canada, ON,
Canada [RT]
Francis J. McCabe, Prefco Products, PA [M]
Gregory IL Miller, Code Consultants Inc., MO [SE]
Stacy R~ Neldhart, Marriott Int'l, Inc., DC [U]
Harold E. Nelson, Hughes Assoc. Inc., MD [SE]
Zenon A. Pihut, Texas Dept. of Health, TX [E]
Dale Rammien, Home Ventilating Inst., IL [M]
Rep. Air Movement & Control Assn. Inc.
James Edward Richardson, Colt Int'l Ltd., England [M]
Todd E. Schumann, HSB Indusu'ial Risk Insurers, IL [I]
~ Brooks Semple, Smoke/Fire risk Mgmt. Inc., VA [SE]
aul Simony, Conspec Systems, lnc., NJ [M]
Paul G. Turnbull, Landis & Gyr Powers, Inc., IL [M]
Staff Liaison: Gregory E. Harrington
Committee Scope: This Committee shall have primary
responsibility for documents on the design, installation, testing,
operation, and maintenance of systems for the control, removal, or
venting of heat or smoke from fires in buildings.
This list represents the membership at the time the Committee was
balloted on the text of this edition. Since that time, changes in the
membership may have occurred. A key to classifications is found at the
front of this book.
The Technical Committee on Smoke Management Systems is
presenting two Reports for adoption, as follows:
Report h The Technical Committee proposes for adoption a
complete revision of NFPA 92A-1996, Recommended Practice for
Smoke-Control Systems. NFPA 92A-1996 is published in Volume
10 of the 1999 National Fire Codes and in separate pamphlet form.
NFPA 92A has been submitted to letter ballot of the Technical
Committee on Smoke Management Systems, which consists of 24
voting members. The results of the balloting, after circt~lation of
any negative votes, can be found in the report.
Alternates
Craig Beyler, Hughes Assoc. Inc., MD [SE]
(Alt. to H. E. Nelson)
Richard J. Davis, Factory Mutual Research Corp., MA [I]
(Alt. to G. Heskestad)
Victor L. Dubrowskl, Code Consultants Inc., MO [SE]
(Alt. to G. R. Miller)
Geraldine Massey, Dillon Consulting Engr, Inc., CA [SE]
(Alt. to M. E. Dillon)
Jayendra S. Parikh, Underwriters Laboratories Inc., IL [RT]
(Alt. to D.J. Kaiser)
James S. Slater, Pittway systems Technology Group, IL [M]
(Alt. to S. E. Egesdal)
Randolph W. Tucker, RolfJensen & Assoc., Inc., TX [SE]
(Alt. to D. L. Arnold)
Report Ih The Technical Committee proposes for adoption a
complete revision of NFPA 92B-1995, Guide for Smoke
Management Systems in Malls, Atria, and Large Areas. NFPA 92B1995 is published in Volume 10 of the 1999 National Fire Codes
and in separate pamphlet form.
NFPA 92B has been submitted to letter ballot of the Technical
Committee on Smoke Management Systems, which consists of 24
voting members. The results of the balloting, after circulation of
any negative votes, can be found in the report.
586
N F P A 9 2 A - - MAY 2 0 0 0 R O P
N~A9~
(Log #CP1)
92A- 1 - (Entire Document): Accept
SUBMITTER: Technic'd Committee on Smoke M a n a g e m e n t Systems
I RECOMMENDATION: The Technical Committee on Smoke
M a n a g e m e n t Systems proposes a complete revision o[ the 1996
edition of NFPA 92A, R e c o m m e n d e d Practice for Smoke-Control
Systems, as shown in the draft at the end of this report.
SUBSTANTIATION: A task group which included four members
of the technical committee (Dan Arnold, J o h n Klote, Gary
Lougheed, and Paul Turnbull), as well as J o h n Kampmeyer
prepared this proposal, as modified by actions taken at the
technical committee's March 1999 ROP meeting, to refine and
update the document. Information based on recent research is
provided for the design a n d tesdng of smoke control systems for
areas of refuge, elevatoc lobbies and hoistways, and vestibules. A
new chapter on computer models for use in the design of smoke
control systems was added. In addition, the sections on control
systems and the fire fighter's control station were refined a n d
clarified.
COMMITTEE ACTION: Accept.
NUMBER O F COMMITTEE MEMBERS ELIGIBLETO VOTE: 24
VOTE ON COMMITTEE ACTION:
AFFIRMATIVE: 21
NOT RETURNED: 3 Carrafa, Chapman, Pihut
COMMENT ON AFFIRMATIVE:
EGESDAL: The r e c o m m e n d e d testing frequency for dedicated
smoke control systems in Paragraph 5-4.3.1 should be weekly, not
semiannually. The required testing frequency for engine-driven
generators (NFPA 72-1996, Table 7-3.2, Item 3) is weekly.
Dedicated smoke control systems, like engine-driven generators, sit
idle with no way to m o n i t o r the ability of the e q u i p m e n t to
function. While the availability of power can be monitored, there
are many mechanical c o m p o n e n t s that cannot be monitored. T h e
present testing frequen=y required as part of the Underwriters
Laboratories listing for dedicated smoke control e q u i p m e n t
"?.-~i~
(UUKL) is weekly. There has been no feedback indicating that a
weekly test frequency for dedicated smoke control systems is too
frequent, or not f r e q u e n t enough.
Additionally, A-3-4.6(e) should be deleted for two r e a s o ~ :
already m e n t i o n e d in A-3-4.6(a) and 5-4.3.1.
...-.%~:~4-~!!!!~-.
MILKE: 1. Section 1-1, lines 10-12: The only chan~]]ouid'-'.~'::::'-~":":"~
to insert the words "limit migration of fire gases" b e ~ ' ~ a l ~ , . ~
a tenable environment...". All that is noted for d e l e ~ o n-~*:'
' ~:':""
~ -~ ' ~ ; { . - ~
being n o t e d as being added.
.....:.~.......:... x;~::::.-;::..
2. Section A-l-7, last line: "Gasses" should ~ ; ~ : .
:~'~""~!.::.
3. Section B-I.I: S h o u l d n ' t the author's ~ ~ . ' I ' a m
be noted in the publication, ' " oke
" " Sv .":"
"=~.~lt inlet:."
Hi~h-rise Buildings. 19947
~:: ":::~.i
:.,.-.%:
RICHARDSON: - 1. Revision of 92B is usin~i~ ~ u r a l v ~ d l a t o r "
instead of "gravity ven61ator," this d o c u m e n t s h i ~ d o . . . . . . ~ e same.
2. We are not convinced by the pressure v e r s u s ~ ' : ' ~ i ~correlation
in Table 2-2.1 and agree with the previous c o m m e .n~-~in this.
SCHUMANN: Page ~1 (Editorial): All of the 4s'| t the chapter
title a n d at the start o f each paragraph n e e d to be lined out. This
is now Chapter 5 a n d so marked.
Page 48 (Editorial): Revise A-4-5 to A- Table 4-5 since the * is on
the table on Page 30 mid n o t the paragraph. Or you can move the
• on Page 30 from the table to Paragraph 4-5.
Page 48, A-5-4: I had a note from the ROP meeting that an
equation was to be added to the paragraph. None was a d d e d and I
have no idea of what equation it was.
TURNBULL: T h e majority of the d o c u m e n t has been
substantially improved by this revision. However, I have concerns
that the changes to Paragraphs 3-4.6 and A-3-4.6 have significantly
r e d u c e d the integrity of dedicated systems.
The 1996 edition of this d o c u m e n t r e c o m m e n d e d supervision
(now called verification) for all dedicated e q u i p m e n t using
methods that automatically verify proper operation each time the
e q u i p m e n t is activated. The r e c o m m e n d e d m e t h o d s did n o t rely
on manual intervention. Chapter 4 (now Chapter 5) contained
additional r e c o m m e n d a t i o n s for Periodic Testing of dedicated
smoke control systems on a semi-annual basis.
The proposed 2000 edition of this d o c u m e n t removed the
distinction between dedicated and non-dedicated e q u i p m e n t in
Paragraph 3-4.6, m e a n i n g that this paragraph now applies to all
smoke control equipment. At the same time, a new item (e)
"Periodic acceptance testing in accordance with Chapter 5" was
a d d e d to the list of verification m e t h o d s in Paragraph A-3-4.6. This
change suggests that e q u i p m e n t should be verified by automatic
means, such as those described in items (a) - (d) OR t h r o u g h
587
semi-annual manual testing. In other words, a non-binding
a g r e e m e n t to test the system twice per year removes the n e e d for
automatic verification. This seems entirely inappropriate, since
system reliability a n d readiness is a desired factor.
Furthermore, combining the discussions of verification m e t h o d s
for dedicated and non-dedicated e q u i p m e n t may result in the
r e c o m m e n d a t i o n s of this d o c u m e n t becoming unclear. Many nondedicated c o m p o n e n t s are operated daily for purposes such as
comfort control, and therefore failures of these c o m p o n e n t s are
generally noticed quickly. E q u i p m e n t operated in this m a n n e r
would n o t normally n e e d the type of verification discussed in
Paragraph A-$-4.6, Items (a) - (d), to provide assurance that the
e q u i p m e n t will operate when activated for smoke control. In
contrast, dedicated e q u i p m e n t a n d some non-dedicated
c o m p o n e n t s are infrequendy or never operated during normal
building conditions. In these cases, automatic verification
methods, such as those described in Items (a) - (d), would be
appropriate. In both cases, the periodic testing described in
Chapter 5 should be performed.
To remedy the situation described above, I r e c o m m e n d the
following changes to the p r o p o s e d document:
1) Restore the word "dedicated ~ to Paragraph 3-4.6 so that it
reads:
"3-4.6* Control System Verification and Instrumentation. Every
system sl-kQ.uldhave means of ensuring it will operate if
activated. The ~ . . . . ~ d
frequency will vary according to the
complexity a n ~ : : [ " ~ p o r ~ c e of the system."
2) Delete ~ ' . . ' ! ~ ) in Paragraph A-$-4.6.
.#.
N~A9~
Practice for Smoke-Control Systems
2000 Edition
Chapter 1 General Information
~.,~" Introduction. All fires p r o d u c e smoke that, if n o t controlled,
i~ll spread t h r o u g h o u t the building or portions of the building,
thereby d
"
"
endangering life
A smoke-control system should be designed to inhibit the flow of
smoke into means of egress, exit passageways, areas of refuge, or
other similar areas of a building. Limiting fire size by providing
automatic sprinklers or other means of automatic suppression will
generally be necessary for effective and economic control of smoke
in most occupancies. O t h e r =¢chn'q'.=e= ~
can be
appropriate for specialized occupancies or existing facilities.
Where smoke-control systems are provided, they should be
activated during the early stages of a fire emergency in order to
m--nt=2n ~ tz==~!c cn;-rc.nmz:=t "~ ".~hz= r z ~ to. ~¢ pr~=zz:z~_.fi~t
mieration o f fire ~ases and to maintain a tenable environment in
the areas to be orotected. The smoke-control system should be
functional during the period of evacuation o f the areas protected
by the system. Such systems are i n t e n d e d to control the migration
of smoke tc ~..~2='.22n tcn=5!c cc=~.~.n: "n into protected areas so
as to nrovide areas of refuee or additional time for e trress, but it
shoulcl n o t be expected that such areas would be completely free o f
smoke. Smoke-control systems should be engineered for the
specific occupancy and building design. Additionally, the smokecontrol system design should be coordinated with other life safety
systems so that they complement, rather than counteract, each
other.
1-2 Scope. This r e c o m m e n d e d practice applies to the design,
installation, testing, operation, a n d m a i n t e n a n c e of new and
retrofitted mechanical air- c c . ~ : i c ~ : : . g ~':~ ;~='5]=~.~
systems fc.r Lhz zc::.:r~! ~ f ~
smoke-control systems. This
pracdce also applies to systems dedicated :v!cl)' tv ~k.c zc='.=c.! c.f
smoke-control systems. (See NFPA 90A. Standard for the Installation
of Air-Conditio~in~ and Ventilating ~3stems. for requ~rem~t, for the
shutdown of smoke-control s~stems and the use of smoke
comOartmentation, i The p r o b l e m of maintaining tenable conditions
witlain large zones of fire origin, such as atria and s h o p p i n g malls,
N F P A 9 2 A - - MAY 2 0 0 0 R O P
together with the quantity o f air that is entrained or otherwise
mixed into the mass.
is not addressed by this document. (See NFPA 92B. Gu/de for
Smoke Management Sostems in Malls. Atria. and Large Areas. "for
maintaining tenable conditions within large zones of tire origin, and
NFPA 2 0 4 ~ , Guide for Smoke and Heat Venting.)
1-3 Purpose. The purpose of this r e c o m m e n d e d practice is to
provide ~uidance in i m p l e m e n t i n g systems using pressure
d:.fferea"_z!~ differeuc¢~ to a c c o m p l i s h o n e or more o f the
following:
Smoke Barrier. A continuous membrane, either vertical or
horizontal, such as a wall, floor, or ceiling assembly, that is
designed and constructed to restrict the m o v e m e n t of smoke. A
smoke barrier maymig[g_ or may might n o t have a fire resistance
rating. ~mok-eSuch barriers maYmigl~ have ~
openings
protected ~)" .~'~-:-~,
. . . . . . dz:~.zz: ~r :dcq~atc --rfl~w:.
(1) Inhibit smoke from entering stairwells, means of egress, areas
of refuge, elevator shafts, or similar areas
Smoke-Control Mode. A p r e d e f i n e d operational configuration of
a system or device for the purpose of smoke control.
(~20 Maintain a tenable environment in thei~l'¢~s of refuge and
means o f egress during the time required for evacuation
Smoke-Control System. An e n g i n e e r e d system that uses
mechanical fans to p r o d u c e ~."fi..~;;~ m=d pressure differences
across smoke barriers to l'm".t ~nd ~ r c c t ~
smoke movement.
(~.$.) C~.n'.rv.! =n~ rc~ucc ~
the gre-ac-ea~ smoke zgne
the migration of smoke from
Smoke-Control Zone. A space within a building enclosed by
smoke barriers, including the top a n d bottom, that is part o f a
z o n e d smoke-control system.
( t J0 Provide conditions outside the fire zone that enable
emergency response personnel to c o n d u c t search and rescue
operations a n d t o locate and control the fire
Smoke Damper. A device that meets the requirements o f UL
555S, Standard for Safe O Leakage Rated Dampers for Use in Smoke
Control Systems, designed to resist the passage o f air or smoke. A
combination fire a n ~ o l t o k e d a m p e r should m e e t the requirements
(d.5..) Contribute to the protection of life and reduction of
property loss
of ~ L 555, s t a , a ~ , C f ~ j e 9 Fi~eDar~rs, and UL 555S.
Smoke E x h ~ # ~ .
A mechanical or gravity system i n t e n d e d
to move s m o l ~ ~ s m o k e
zone to the exterior of the
building,..~]~fl~u~01.ng srm~. Krem. oval, purging,
rag, :a n d venting systems,
as w e l l ~ eqlq~~ i o n
d~~ s t fans utilized to reduce the
p r e ~ ' / ~ in:..it smoke zone, ~.~,ufintenance o f a tenable environment
m~ol~'.~one
is not~ 'thin the capability o f these systems.
1-4 Definitions. For the purposes of this r e c o m m e n d e d practice,
the following terms will have the meanings given in this chapter.
Approved.* Acceptable to the authority having jurisdiction.
Area 9 f Refuge. An area o f the building separated from other
spaces by fire-rated smoke barriers in whfch a tenable e n v i r o n m e n t
is maintained for the oeriod of time that such areas may n e e d to be
occupied at time o f fire.
S m o k ' ~ " ~ e . :Ofhe smoke-control zone in which the fire is
located.
q ' h e vertical airflow within buildings caused by the
differences between the building
exterior or between two interior snaces.
Authority Having Jurisdiction.* T h e organization, office, or
individual responsible for approving equipment, an installation, or
a procedure.
.'~':".~:::;::::9
~i::~:-':-~
Environment. An environment in which .t. . . . . . . . :. . . .
smoke and heat is limited or otherwise restricted to
on occupants to a level that is n o t life threatening.
Zoned Smoke Control. A smoke-control system that includes
smoke exhaust for the smoke zone and pressurization for all
contiguous smoke-control zones. T h e remaining smoke-control
zones in the building also may be pressurized.
1-5 Principles o f Smoke Control.
1-5.1 Basic Principles. Frequently smoke flow follows the overall
air m o v e m e n t within a building. Although a fire may be confined
within a fire-resistive compartment, smoke can readily spread to
adjacent areas t h r o u g h openings such as construction cracks, pipe
penetrations, ducts, a n d open doors. T h e principal factors that
cause smoke to spread to areas outside a c o m p a r t m e n t are as
follows:
been activated, such as during smoke control, testing, or manual
overridg operations. Failure or cessation of such oositive
confirmation results in an off-normal indication.
Fire Fighters' Smoke-Control Station (FSCS). A system that
provides graphical monitoring and manual overriding
capability over smoke-control systems and e q u i p m e n t l ~ i d o ~ a t
designated location(s) within the building for the use of t h e fire
department. O t h e r fire fighters' systems (such as voice alarm,
public address, fire d e p a r t m e n t communication, a n d elevator
status a n d controls) are n o t covered in this document.
(1) Stack effect
(2) Temperature effect of fire
(3) Weather conditions, particularly wind and temperature
Pressurized Sm!~o'.¢c~ ~
A type of smoke-control
system in which stair shafts are mechanically pressurized, with
resoect to the fire area. with o u t d o o r air to keep smoke from
contaminating t h e m during a fire i n d d e n t .
(4) Mechanical air-handling systems
The factors listed in 1-5.1(1) t h r o u g h (4) cause pressure
differences across partitions, walls, and floors that can result in the
spread of smoke. T h e m o v e m e n t o f smoke can be controlled by
altering these pressure differences. Building c o m p o n e n t s and
e q u i p m e n t such as walls, floors, doors, dampers, a n d s m o k e p r o o f
:tr2rt~.'::c= ~
can all be utilized along with the heating,
ventilating, a n d air-conditioning (HVAC) systems to aid in the
control of the m o v e m e n t o f smoke. Proper overall building design
and tight construction are essential to smoke control.
"
The dilution o f smoke in the fire area o f a c o m p a r t m e n t e d
building is n o t a means of achieving smoke control. Smoke
R e c o m m e n d e d Practice. A d o c u m e n t that is similar in c o n t e n t
and structure to a code or standard but that contains only
n o n m a n d a t o r y provisions using the word "should" to indicate
r e c o m m e n d a t i o n s in the body o f the text.
Should. Indicates a r e c o m m e n d a t i o n or that which is advised but
n o t required.
Smoke. The airborne solid a n d liquid particulates a n d gases
evolved when a material undergoes pyrolysis or combustion,
588
N F P A 92A ~
MAY 2000 R O P
control cannot be achieved simply by supplying air to a n d
exhausting air from the compartment.
the pressure needs to be e n o u g h that it is n o t overcome by the
forces of wind, stack effect, or buoyancy of h o t smoke.
Smoke control can be stated in two basic principles as follows:
1-6.,5 Airflow. Airflow can be used to limit smoke migration when
doors in smoke-control barriers are open. The design velodty
t h r o u g h an open d o o r should be sufficient to p r - e v e n ~
smoke backflow during building evacuation. The design velocity
should take into consideration the same variables as used in the
"selection of design pressure differences.
" "
" "s
provided in ASHRAE/SFPE. Design of Smoke Management S~stems.
(1) Air pressure differences of sufficient magnitude acting across
barriers will control smoke movement.
(2) Airflow by itself ~.11 control smoke m o v e m e n t if the average
air velocity is of sufficient magnitude.
1-5.2 Pressurization. T h e primary means of controlling smoke
m o v e m e n t is by creating air pressure differences across partitions,
floors, and o t h e r building components. The basic concept of
building pressurization ts to establish a higher pressure in adjacent
spaces than in the smoke zone. In this way, air moves into the
smoke zone from adjacent areas a n d smoke is inhibited from
dispersing t h r o u g h o u t tae building.
1-6.6 N u m b e r o f Doors Open. The n u m b e r of doors that could
be open simultaneously should be considered. This n u m b e r will
d e p e n d largely on the building occupancy and the type of smokecontrol system. In some systems, doors will most likely be o p e n for
only short periods o f time a n d the smoke leakage will be negligible.
(For the n~mber of doors oben in a stairwell Oressurlzation s~stem~ see
1-5.3" Airflow. Airflow at sufficient velocity can bc u:cd tc :t~.p
restrict smoke m o v e m e n t t!'.rcugh -. .~. v. . . . . . This principle is most
commonly used to control smoke m o v e m e n t t h r o u g h openjllgr~
a. . . . ....... . . .~. . The flow of.alr through the o p e n i n g into the smoke
zone must be of sufficient velocity to pr-event limit migration of
smoke from kmM-ng- that zone t h r o u g h such openings. The doors
in these donnings are not onen for loner neriods of time. so this
Fepresents a transient condition that is necessary in order to
provide egress from. or access to. the smoke zone (See NFPA 92B.
1-7_* Fire Suppression Systems. Automatic sprinkler a n d other fire
suppression systems are an integral part of many fire protection
designs a n d the reliability a n d efficiency of such s ~ t e m s in
controlling building fires is well d o c u m e n t e d . It Is important to
recognize that the functions of both suppression and smokecontrol systems are j ~ . o r t a n t . Automatic suppression systems can
extinguish a fire ~ T ~ r ~ s
growth, thereby eliminating additional
smoke g e n e r a 6 ~
D n the other hand, well-designed smokecontrol systet~". ~ n t a i n
a tenable environment along critical
egress r o u ~ . . ~ [ ~ r i n g ~ m e it takes the fire suppression system or
fire s e r v i ~ e 4 ~ ' . . ~ n e l f ~ i e g e
final extinguishment.
G~ide for Smoke Mana~,ement S~stems in Malls. Atria. and Laree
Since "~c qua='2"Scz cf - r r c q u ' r c ~ =re l----'gc, --rfi.cv: - n e t
In ~tio~..to the fact~ ' ; ~ e systems perform different
fu.~
i~.~.~mportant~o consider the interaction between the
fire suppression systems. For example, in a
s m "o k ~ n d
fully s p : ~ . e d
building, pressure differences and airflows n e e d e d
to control ~:.~..~ovement may be less than in an unsprinklered
.'.:~lk'&.ldingdue ~.~:-xne likelihood that the m a x i m u m fire size will be
~fli~:*
# ~ d l e r than in an unsprinklered building.
1-6 Design Parameters.
1-6.1 General. Dez:.g:z ,~',^.z . . . . .
:~.~ :~ .t. .......
:. . . . a . . . .
t~.c stz.'zd.~r?~=rcfcrcncc~ !z7 uhcm :hcu!d ~ . . . .. .-~. . u .~............. .,. ~.~z~'~"
!!..::.~
~eous
Control system can adversely affect t h e p e r f o r m a n c e of
agent, such as the clean a~ents as d e f i n e d i n NFPA 2001.
"i.;..(
- ' .
" -. " "
.Hal°n'
or C O , r
systems where the systems axe located in a
~.~ommon space. In the event that both systems are activated
' concurrently, the smoke-control system might dilute the gaseous
agent in the space. Because gaseous suppression systems
commonly provide only one application of the agent, the potential
arises for renewed growth o f the fire. Gaseous suppression systems
and smoke-control systems cannot perform their i n t e n d e d
functions simultaneously when they are located within the same
space.
!ncludc :.-= An understanding with the authority h a v i n g j u r i s ~ : :
of the expected performance of the system and the a c c e p ~ c e t ~
procedures sh0~lql, be established early in the design. ~ l e d
.-'~.~:
engineering design information is contained in ~
~
publication, Design of Smoke Management Systems,
. :~
1-6.2 Leakage Area&.
/ca-} Small openings in smoke barriers, such as c o n ~ c t i o n
joints, cracks, closed-door gaps, and similar c l e a r a n ~ s , should be
addressed in terms of maintaining an adequate pressure difference
across the smoke barrier, with the positive pressure outside o f the
smoke zone. Tvoical leakage areas are listed in Table 4-5.
Chapter 2 Smoke-Control Systems and Applicability
Ogt- Large openings in smoke barriers, such as doors i n t e n d e d to
be open a n d other sizable openings, should be addressed. These
o n e n i n ~ should be e~duated based on geometric area. "~ntc.."m: e f
2-1 Introduction.
1-6.3_* Weather Data. The temperature differences between the
exterior and interior of the building cause stack effect and
determine its direction and magnitude. The effect of temperature
and wind velocity will ~ r y with building height, configurauon,
leakage, a n d openings in wall and floor construction. The system
designer reouires s u m m e r and winter design temoeratures. For
full analvsls, wind data also needs to be considered.
Determination o f system objectives a n d performance criteria
should be made prior to design or construction.
2-1.1 Purpose. This chapter discusses various types of smokecontrol systems cu.':enfl7 :;--!a~Ic and reviews the advantages and
disadvantages of each type.
2-1.2 Dedicated and Nondedicated Systems.
2-1.2.1 Dedicated Systems. Dedicated smoke-control systems are
i ~ - e t ~ e d i n s ~ l e d for the sole purpose of p.Lq_vi.0j~ smoke control
o~Pf. They are separate systems of air-moving and distribution
e q u i p m e n t that do n o t function u n d e r normal building operating
conditions. U p o n activation, these systems operate specifically to
p e r f o r m the smoke-control function.
1-6.4 Pressure Differences. The m a x i m u m and m i n i m u m
allowable pressure differences across the boundaries of smokecontrol zones should be considered. The maximum allowable
pressure difference should n o t result in door-opening forces that
exceed the requirements of NFPA 101®, Life Safely Code@, or local
codes and regulations. The m i n i m u m allowable pressure
difference should be such that there will be no significant smoke
leakage during building evacuation. For the system to be effective,
AdvaIltages of dedicated systems h:;'z ".b.: f~l!v:'-ng : d ' . x n ' ~ g ~
include the following:
(1) Modification of thes_.~Lt_gmcontrols during ~):tc.'..
m^.2~,tcn^.~qzcafter installation is less likely t-o--oc-eu~.
589
NFPA 92A ~
MAY 2 0 0 0 R O P
(5) Building o c c u p a n c y
(2) O p e r a t i o n a n d control of system generally simpler.
2-2 Pressure D i f f e r e n c e s .
(3) w,.~.,
are ! e ~ !!kc!y t~ ~c :fleeted Reliance on or i m n a c t by
....
1
"~c mc'~--Sca'-~ c f o t h e r building systems is limited.
-r,.^.. i. . . . . . ~'^ ~ ' ~ " " - ~
include t h e following:
(~j,)
2-2.1" Table 2-2.1 presents suggested m i n i m u m design pressure
differences developed for gas t e m p e r a t u r e o f 1700°F (92~°C) n e x t
to the s m o k e barrier. T h e s ~ pressure d i f f e r e n c ~ are
r e c o m m e n d e d for desit, n s t h a t are based on m a i n t a i n i n ~ m i n i m u m
nressure differences between snecified snaces.
Disadvantages of dedicated systems
If it is desired to calculate pressure differences for gas
t e m p e r a t u r e s o t h e r t h a n 1700°F (925°C), t h e m e t h o d described in
A-2-2.1 can be used. Pressure differences p r o d u c e d by smokecontrol systems t e n d to fluctuate d u e to t h e wind, fan pulsations,
doors o p e n i n g , d o o r s closing, a n d o t h e r factors. Short-term
deviations f r o m t h e s u g g e s t e d m i n i m u m design pressure difference
m a y n o t have a serious effect o n t h e protection provided by a
smoke-control system. T h e r e is n o clear-cut allowable value of this
deviation. It d e p e n d s on tightness of doors, tightness of
construction, toxicity of smoke, airflow rates, a n d o n t h e volumes
of spaces. I n t e r m i t t e n t deviations u p to 50 p e r c e n t of t h e suggested
m i n i m u m design pressure difference are c o n s i d e r e d tolerable in
m o s t cases.
-"
. . .. .. .. . .v. .. .. . . . . . . .,~:
. . . .. .. . . . . System i m n a i r m e n t s m a y go
~Bdiscovered between periodic ~ests or m ~ n t e n a n c ~ activities.
(~J 2) Systems ~ e ~ r e ~ d y can require m o r e b u i l d i t ~
space.
2-1.2.2 N o n d e d l c a t e d Systems. N o n d e d i c a t e d systems are t h o s e
t h a t s h a r e c o m p o n e n t s with s o m e o t h e r system(s) s u c h as t h e
building HVAC system. Activation causes t h e system to c h a n g e its
m o d e of operation in o r d e r to achieve t h e smoke-control
objectives.
Table 2-2.1
Advantages of n o n d e d i c a t e d systems h"-:'¢ ~he fc!!c-:-.'ng ~-.a.a:~-:xage:
i n c l u d e t h e following:
ested Minimum Design Pressure
s Across Smoke Barffers I
l m p m"r m e n l s to s h a r e d e q u i p m e n t
( 1 ) ". . . . . . .v. . . . . . . . . . . . . . . . .
r e q u i r e d for n o r m a l building o p e r a t i o n are tess-likely to r-emai~ be
uB-corrected ~ .
(2) E q u ' ~ m e a t cozY, m a y ~c lower.
19~.~
(g~
21 ft
~
additional space for smoke-control e q u i p m e n t m a y
is necessary.
Notes:
~-~..' For d e ~ $ i purposes, a smoke-control system s h o u l d
-~:?:.i! ~-.~-. . . . .
~~-~'%se
r a m , m u m pressure differences u n d e r
~Y!~"
..::~;;!iR'~nditions--~=:~- of stack effect or wind.
• z$ A S
: ' - sprinklered, NS - - nonsprinklered.
..:~g...-. For z o n e d smoke-control systems, t h e pressure
~!!gi~ifference is m e a s u r e d between t h e s m o k e zone a n d
:: .¢#" adjacent spaces while t h e affected areas are in t h e smokes:" control m o d e .
T~cy ~ave u~.c fcllc;;'i=g Disadvantages of n o n d e d i c a t e d systems
include t h e following:
(l)
System control m a y b e c o m e elaborate.
(2) .'=~,.:==:=:=o~::=--:= ~
,.~.:-.:-:':-~g
.:.~:."
~?.~-~'.,.
o f ~ ~ : :
or controls affec-tng c a n i m n a l r smoke-control f ~ " " ' ~ g , * ~ ! : ~
m o r e !!kcl 7 tc occur.
~"::g.:j~:'.:....
.... ~. . . . . . .
~;^~
.-:::::"
0.10
0.14
0.18
2-2.2_* Similar to t h e pressure differences across s m o k e barriers,
t h e pressure differences across d o o r s s h o u l d n o t exceed t h e values
given in Table 2-2.2, so that t h e doors can be operated while the
pressurization system is operating. T h e s e pressure difference
values are based o n t h e 30-1bf (133-N) m a x i m u m force p e r m i t t e d
to begin o p e n i n g t h e d o o r stipulated in NFPA 101, Life Safety Code.
"::::i:.<:-.~.,
2-1.3 Basic System T~pes. Systems for c o n t r o l ~ > # m o k e ~i!
m o v e m e n t in a building can generally be d i v i d e d : : ~ , tw o ~ p a r a t e
types: shaft protection a n d floor protection. Shaft"~*.~.¢~[on can
be further divided into s m i e t o ~ e F s ~ i ~ e l l p r e s s u r i z a i ~ l systems
a n d elevator hoistway systems. Floor protection enO$i~npasses
several variations of z o n e d s m o k e control. Use of a particular
system or c o m b i n a t i o n of systems is d e p e n d e n t on building a n d
fire code r e q u i r e m e n t s , as well as t h e specific o c c u p a n c y a n d life
safety r e q u i r e m e n t s of t h e situation b e i n g considered.
2-3 S'wArtw.':cr ~
Pressurization Systems.
2-3.1 General. T h e p e r f o r m a n c e goal of pressurized :*~.rtw::er:
is to provide a tenable e n v i r o n m e n t within the
in t h e event of a building fire. A s e c o n d a r y objective is to
provide a staging area for fire fighters. O n t h e fire floor, a
pressurized ~ s ~ e f l
n e e d s to m a i n t a i n a pressure
difference across a closed s m l e t - o ~ ~
d o o r so that s m o k e
infiltration is limited. T h e stairwell nressurization svstem s h o u l d
be d e s i g n e d to m e e t or exceed t h e m i n i m u m design nressure
differences Liven in Table 2-2.1 b u t s h o u l d n o t e~ceecl th~
m a x i m u m nressure differences Liven in Table 2-2,2, (Refer ~
Section 2-6-when stairwell bressu~ization s~stems are used in
combina~on with o~her smoke-control ~ s t e ~ , )
2-1.4 T e n a b l e Environment. A n o n s m o k e zone of a z o n e d smokecontrol system can be used as a n area i n t e n d e d to protect
occupants for t h e period of time n e e d e d for evacuation or can be
used to nrovlde an area of refu~e. T h e c:mcc~t ~f a - c : ~f t c : a b ! e
2-1.5 System Integrity. Smoke-control systems s h o u l d be designed,
installed, a n d m a i n t a i n e d such that t h e system will r e m a i n effective
durin.~ evacuation of the protected areas. O t h e r considerations
m a y thctate t h a t a system s h o u l d r e m a i n effective for l o n g e r periods
of time. Items t h a t s h o u l d be c o n s i d e r e d are as follows:
2-3.2
(1) Reliability of power source(s)
(2) A r r a n g e m e n t of power distribution
(3) M e t h o d a n d protection of controls a n d system m o n i t o r i n g
(4) E q u i p m e n t materials a n d construction
59O
Noocompensated
and Compensated
Systems.
N F P A 92A ~ MAY 2000 R O P
Table 2-2.2 Maximum Pressure Differences Across Doors t'~,s,*
Door Closer
Door Width
~n. w.g./"
Force ~ (Ibf)
32
~8
44
48
6
0.45
0.40
0.37
0.34
0.31
8
0.41
0.37
0.34
0.31
0.28
10
0.37
0.34
0.30
0.28
0.26
12
0.34
0.30
0.27
0.25
0.23
14
0.30
0.27
0.24
0.22
0.21
For SI units, 1 Ibf = 4.4 N; 1 in. = 25.4 mm; 0.1 in. w.g. = 25 Pa.
Total door opening force is 30 lbf.
Door height ~s 7 ft.
The distance from the doorknob to the knob side of the door is 3 in.
For other door-opening forces, other door sizes, or hardware other than a knob, for example, panic hardware, use the
calculation procedure provided in the ASHRAE/SFPE publication, Design of Smoke Management Systems.
Many door closers require less force in the initial portion of the opening cycle than that required'to bring the door to the fully
open position. The combined impact of the door closer and the imposed pressure combine only until the door is opened enough
to allow air to'pass freely through the opening. The force imposed by a closing device to close the door is often different from that
imposed on opening.
b o o r widths apply only if door is hinged at one end; otherwise, use the calculation procedure provided in ASHRAE/SFPE.
Design of Smoke Management Systems.
2-3.2.1 In a noncompettsated system, supply air is injected into the
~stai~ell
by actuating a single-speed fan, thus providing
one pressure difference with all doors closed, another difference
with one door open, and so on.
Roof
2-3.2.2 Compensated systems adjust to various combinations of
doors that are open and. closed, while maintaining positive
pressure differences across such openings. Systems compensate for
changing conditions by either modulating supply airflows or by
relieving excess pressure from the m ~ w e ~ s ~ i ~ e l l .
The response time of the control system should be closely
evaluated to ensure that pressures do not fall below the short-term
values given in Table 2-2.1. The location of the exhaust inlet
from the s~wc-e,wer-~,~_.gl]. relative to the supply outlet(s)
w~.'~;~" ~
~s~i~el/occur.
should be such that short-circuiting ~:..
~!!!..,
2-3.2.2.1 Modulating Supply Airflow. In a modulating s u ~
~
airflow system, the capa,.nty of the supply fan is
"ovit
least the minimum air velocity when the desig
~dc
~
are open. Figure 2-3.2.,,.1 illustrates such a<..~.
:~':"'
of air into the ~ s ~ i ~ e l l
is varie~g~/:~
g
dampers, which are controlled by one or mot
ess~..'e
sensors that sense the pressure difference betwe,
~ e F
s~rwell and the building. When all the ~
. ~ , L doors
are closed, the pressure difference increases and the
pass
damper opens to increase the bypass air and decreas~ ae flow of
supply air to the ~ s ~ r w e l l .
In this manner, excessive
pressure differences between the ~air-t-oweestai~ell and the
building are prevented. The same effect can be achieved by the use
of relief dampers on the supply duct when the fan is located
outside the building. Supply airflow modulation may also be
accomplished by varying fan speed, inlet vanes, variable pitch fan
blades, or number of fans operating. Response times of the
controls with any system should be considered.
~" Fan
Notes:
1. Fan bypass controlled by one or more static pressure sensors
Iocatedbetween the stairtower and the building interior.
2. A ground-level supply fan is shown; however, tan(s) could be
located at any level.
Figure 2-3.2.2.1 S'.c~cwc:"~
pressurization with bypass
around supply fan.
Overpressure relief may be accomplished by one of the following
four methods.
(a) Barometric dampers with adjustable counterweights can be
used to allow the damper to open when the maximum interior
pressure is reached. This represents the simplest, least expensive
method of overpressure relief because there is no physical
interconnection between the dampers and the fan. The location of
the dampers needs to be chosen carefully because dampers located
too close to tile supply openings can operate too quickly and not
allow the system to meet the pressure requirements throughout the
~stai~ell.
The dampers can be subject to chattering
during operation. Figure 2-3.2.2.2 illustrates overpressure relief
using barometric dampers.
2-3.2.2.20verpressure Relief. Compensated system operation can
also be accomplished by overpressure relief. In this instance,
pressure buildup in the ~ s m i ~ e l l
as doors close is
relieved direcdy from the s t a i r - t o w e e ~
to the outside. The
amount of air relieved varies with the n u m b e r of doors open, thus
attempting to achieve an essentially constant pressure in the
s ~ 4 t o ~ a ~ s ~ i ~ e l l . Exterior relief openings can be subject to
adverse effects from the wind so windbreaks or windshields are
recommended.
(b) Motor-operated dampers with pneumatic or electric motor
operators are another option for overpressure relief. These
dampers are to be controlled by differential pressure controls
located in the ~ , ~ , ~ w e ~ .
This method provides more
positive control over the ~ s t a i ~ e l l
pressures than
barometric dampers. It requires more control than the barometric
dampers and therefore is more complicated and cosily.
I~ c:d~t'~g ~u!!~ng~, ~ overpressure relief m a ? ~ i s to be
discharged into the building,,~-h~ the effects of this on the
integrity of the z~'rto;;':.'r= ~
and the interaction with other
building HVAC systems should be closely studied ~efvre prcFv=:'ng
th'z m..z'~o~. Systems using this principle should have combination
fire/smoke dampers in the ~ a i e t o ~ - ~
wall penetrations.
(c) An alternate method of venting a ~ s ~ i ~ e l l
is
through an automatic-opening ~
~
door or vent to
the outside at ground level. Under normal conditions this door
591
N F P A 9 2 A - - MAY 2 0 0 0 R O P
would be closed and, in most cases, locked for security reasons.
Provisions n e e d to be made to ensure that this lock does n o t
conflict with the automatic operation of the system.
2-3.4.1.1 Simple single-point injection systems such as that
illustrated in Figure 2-3.4.1.1 can use a r o o f or exterior wallm o u n t e d propeller fan to supply air to stairwells. The use of
propeller fans without windshields is not r e c o m m e n d e d because of
the extreme effect wind can have on the performance o f such fans.
Possible adverse wind effects are also a concern with a system that
uses an c.pcn a a ~ ' ~ c a-.cc.r 9pening to the exterior at g r o u n d level
as a vent. Occasionally, high local wind velocities develop near the
e x t e r i o r s t a i r - t o w ~ s t a i ~ e l l door. Such local winds are difficult to
estimate in the vicinity of new buildings without expensive
modeling. Adjacent objects can act as windbreaks or windshields.
Systems udlizin~ vents to the outside of g r o u n d level are more
effective u n d e r cold conditions with the stack effect assisting the
stair pressurization system for stairwells primarily abgve grade,
2-3.4.1.2 O n e major advantage of using propeller fans for stairwell
pressurization is that they have a relatively flat pressure response
curve with respect to varying flow• Therefore, propeller fans
quickly r e s p o n d to airflow changes in the stak-towe~ s t a i ~ e l l as
doors are o p e n e d and closed without major pressure fluctuations•
A second advantage o f using propeller fans is that they are less
costly than other types of fans a n d can provide adequate smoke
control with lower installation costs.
(d) An exhaust fan can be used to prevent excessive pressure
when all ~
~
doors are closed. The fan should be
controlled by a differential pressure sensor so that it will n o t
operate when the pressure difference between the staietow~e
and the building falls below a specified level. This should
prevent the fan from pulling smoke into the ~tk-toa~ee s ~ i ~ e l l
when a n u m b e r of open doors have r e d u c e d s t i f i r - t ~ s ~ s ~ r w e l l
pressurization. Such an exhaust fan should be specifically sized so
that the pressurization system will perform within design limits. To
achieve the desired performance, it is believed that the exhaust fan
control should be o f a modulating type as opposed to an on-off
type. Because an exhaust fan will be adversely affected by the wind,
a windshield is r e c o m m e n d e d •
2-3.4.1.3 A disadvantage of using propeller fans is that they often
require windshields at the intake because they operate at low
pressures and are readily affected by the wind pressure o n the
building. This is less critical on roofs where the-fans are often
protected by parapets a n d where the direction o f the wind is at
right angles to the axis o f the fan.
Propeller fans m o u n t e d on walls pose the greatest susceptibility to
the adverse effects of...~.'nd pressures. The adverse effect will be at a
maximum when w i ~ e c t i o n
is in direct opposition to the fan
airflow, r e s u l t i n g ~ a IoC'~r intake pressure a n. d . thus
significantly
. .
r e d u c m g fan e ~ n e s s .
Winds that are variable m mtenslty and
direction a l s ~ o s e ' ~ " ~ e a t to the ability of the system to maintain
control o~:.~:
v a . ?7-Kg'
. "~.#..tatic
pressure.
.,..Istai
..:.~:~.......,
x~,~:.:-.~':~ ~:'.::::::~::~. ~::,~-#- , ~...
.:-~.~:i'~
:~.-: ~'.-:.-'.~.
Propeller
•
Roof
level
rv.¢:::
Roof
level
,.%upply
_ air
5"
Note: Supply fan could be located at iiny I ~ .
~i.':'~.':"
~-x._
~:"'":':'::"
2-3.2.2.2 s.-'__-:==,o:
vent to the outside.
¥::~
A-'-';
I
|
:~.~-x:.~':"
x.._
•
|
Figure 2-3.4.1. I S'~--~vv:== ~
pressurization by
r o o f - m o u n t e d propeller fan.
2-3.3 Supply Air Source Location.
2-3.4.2 O t h e r Types o f Fans. O t h e r single-injection systems and
multiple-injection systems might require the use of a centrifugal or
an in-line axial fan to overcome t h e increased resistance to flow in
the supply ductwork to the staif-toweestai~ell.
2-3.3.1 The supply air intake should be separated from all building
exhausts, outlets from smoke shafts and r o o f smoke and heat vents,
open vents from elevator shafts, and o t h e r building openings that
might expel smoke from the building in a fire. This separation
should be as great as is practicable• Because h o t smoke rises,
consideration should be given to locating supply air intakes below
such critical openings. However, o u t d o o r smoke m o v e m e n t that
might result in smoke feedback d e p e n d s on location of the fire,
location of points of smoke leakage from the building, wind speed
a n d direction, and the temperature difference between the smoke
a n d the outside air. At present, sufficient information is n o t
available about such outdoor smoke m o v e m e n t to warrant general
r e c o m m e n d a t i o n s favoring ground-level intakes rather than rooflevel intakes.
2-3.5 Single and Multiple Injection.
2-3.5.1 Single Injection.
2-3.5.1.1 A single-injection sTstem is one that has pressurization air
supplied to the ~ s t a J ~ e l l
at one location. The most
c o m m o n injection point is at the top o f the stairwell, as illustrated
in Figure 2-3,5.1.
2-3.3.2 With a n y ~ s t a i ~ e l l
pressurization system, there is
a potential for smoke feedback into the pressurized ~ a i r - t o ¢ ~
from smoke entering the ~ i i - r t o , a e ~ s ~ i ~ e l l through the
pressurization fan intake. Therefore, the capability o f automatic
shutdown in the event o f smoke feedback should be considered.
2-5.4 Supply Air Fans.
2-3.4.1 Propeller Fans. Advantages and fimitatious o n the use of
propeller fans are described in 2-~.4.1.1 t h r o u g h 2-~.4.1.3.
592
NFPA 92A ~
Centrifugal
MAY 2000 ROP
~......j~
.,,---r'~-~./Centrifugal
Roof
Roof
level
level
aft
Figure 2-3.5.1 8mir-tower-S~i~ell pressurization by top injection.
Figure 2-$.5.2.1(b) S'^--~c"-'cr S t ~ e f l
pressurization by multiple
injection with roof-mounted fan.
2-3.5.1.2 Single-injection systems can fail when a few doors are
open near the air supply injection point. All of the pressurization
air can be lost through these open doors, and the system will then
fail to maintain positive pressures across doors farther from the
injection point.
2-$.5.2.2 In Figures '~$.5.2.1
,
(a) and 2-3.5.2.1 (b), the supply duct is
shown in a s e p a:at~l~7-.
rat~
However, systems have been built that
have eliminated ~t~"~dx~g~se
t~'~
of a separate duct shaft by locating the
supply duct in
in ...t~t~
~ r
enclosure itself. Care needs to be taken so
that the d u c~t .e~se"s~"e~d u c e
the required exit width or become an
o b s t r u c t i o ~ . ~ d e r ~ ? n g~_ _ , , ~ , ~ evacuation.
2-3.5.1.3 Because a ground-level o t a g v t o w ~ - s ~ e l l door is likely
to be in the open position much of the time, a single-bottominjection system is especially prone to failure. Consideration of
this specific situation as well as overall careful design analysis is
required for all single-bottom-injection systems, and for all other
single-injectlon systems for :m'rt~wc~ ~
in excess of 100 ft
(30.5 m) in height.
2-$.5.~*J~" M a I ~ m u l t i p l ~ o n
systems have been bu,lt with
supl~[air i t ~ c u o n
" "" each floor. These systems represent
tl~atg~.lareventing
loss of pressurization air through a few
open ~ ' l i ~ e v e r ,
that many injection points might not be
cessar
~..r system desi[gns yam
neces
with mje,
injection points more than
three
e e stor ~
the designer should use a computer analysis
~[a as the o._f~_'~=n.ASHRAE/ SFPE, Design of Smite Management
2-3.5.2 Multiple Injection.
3 " y ~ ' ~ 9 ~ t g a n a l y s i s is to ensure that loss of pressurization air
~ ~ W
open doors does not lead to substantial loss of
. ~
s~ell
pressurization.
2-3.5.2.1 A multiple in~ection system is one in which air is supplied
to the stairwell at muinpie points. Figures 2-3.5.2.1(a) and~_...~.'.'..'~.~
2-3.5.2.1(b) are two examples of many possible m u l t i p l e - i ~
systems that can be used to overcome the limitations of~iigle- ~-.'~
injection systems. The pressurization fans can be I o ~ f g g%
r o~. ~ ....$: •
level, roof level, or at any location in between.
..~-~.-..~.
Roof
t~ Vestibules. ~m;rt~wz~ S ~ e l l s that do not have vestthules
.aga be pressurized adequately using ~
currently available
~ - h n i q u ~ . Some buildings are constructed with vestibules
because of building code requirements. These vestibules may be
either nonpressurized or pressurized.
[
2-$.6.1 Nonpressurized Vestibules. S::~,¢,;;'cr= ~
that have
nonpressurized vestibules can have applications in existing
buildings. With both vestibule doors open, the two doors in series
provide an increased resistance to airflow compared to a single
door. This increased resistance will reduce the required airflow so
as to produce a given pressure in the ~ s t a i ~ e l l .
This
subject is discussed in detail in ASHRAE/SFPE. Design of Smoke
level
Management Systems.
.~
x
~
J I I
/
In buildings with low occupant loads, it is possible that one of the
two vestibule doors may be closed, or at least partially closed,
during the evacuation period. This will further reduce the
required airflow to produce a given pressure.
Duct
fan
2-3.6.2 Pressurized Vestibules and Stairwells. To minimize the
~roount of smoke that enters a vestibule and stairwell, both the
vestibule and stairwell can be pressurized. The combined svstem
will enhance the effectiveness of the stairwell Dressurization swstem.
AIs9, the pressurized vestibule can nrovide a temvorarv area of
,
Figure 2-3.5.2°I (a) S m i F t e w e e S t ~ e l l pressurization by multiple
injection with the fan located at ground level.
ur_e_fu~
2-$.6.3 Pressurized Vestibules. With both doors closed, the smoke
entering a vestibule can be limited so as to vrovide a tenable
environment as an area of refuge. The adjacent stairwell is
indirectly pressurized bv airflow from the pressurized vestibule.
However. this t~ressurizafion can be lost if the exterior door is
open. Also. smoke can flow into the stairwell through any leakage
openings iO the stairwell walls adjacent to the floor snace. Such
walls should be constructed to minimize leakages for-a stairwell
vrotected bv a vressurized vestibule svstem.
593
NFPA 92A
-
-
MAY 2000 ROP
23.6.4 Purged or V e n t e d Vestibules. Purged or vented vestibule
systems fall outside the scone of this document. A hazard analysis
would be reuuired using the Drocedures provided in the SFPE
H~ndbqqk of-Fire Protection EnMneerin~. Prep-curl)" there arc no
,mca.qa a':ailable An en~ineerimt analysis should be n e r f o r m e d to
ata=atyze-~
the benefits,-if any, of pressurizing, purging, or
exhausting vestibules on the ~
2-5.1
2-5.1.1 The pressurized atz.!rtcwcr~ ~
discussed in Section
2-3 are i n t e n d e d to control smoke to the extent that they inhibit
smoke infiltration into the s * = a i r - t o ~ ~ .
However, in a
building with just a pressurized stsfr-to,a~ ~
smoke can flow
t h r o u g h cracks in floors and partitions and t h r o u g h other shafts to
threaten life and to damage property at locations remote from the
fire. The concept of zoned smoke control discussed in this section
is intended to limit this type of smoke m o v e m e n t within a building.
2 ~.7 FL-e ~ c c r Exha'_'='..
. . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . .
pc~rmcd
~
. . . . . . . . . . .
I" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
[~ . . . . . . . . . . . . . . . . . . .
2-5.1.2 Limiting fire size (mass b u r n i n g rate) increases the
reliability a n d viability of smoke-control systems. Fire size can be
limited by fuel control, c o m p a r t m e n t a d o n , or automatic sprinklers.
It is possible to provide smoke control in buildings n o t having firelimiting features, but in those instances, careful consideration must
be given to fire pressure, high temperatures, mass b u r n i n g rates,
accumulation of u n b u r n e d fuels, and other outputs resulting from
uncontrolled fires.
] . . . . . . . . . . . . . . . . . . .
~cfore c¢za'dcring th'~ concept.
2-5.2 Smoke-Control Zones.
2-3.7* N u m b e r o f D o o r s Onen.
2-5.2.1 Some buildings can be divided into a n u m b e r of smokecontrol zones, each zone separated from the others by partitions,
floors, and doors t h ~ . . ~ be closed to inhibit the m o v e m e n t of
smoke. A s m o k e - q ~ ' ~ . . z o n e can consist of one or more floors,
or a floor can c9~ - ~t of'~'ne or m o r e smoke-control zones.
Arrangemen~:~.
8 smoke-control zones are illustrated in
Figure 2 - 5 . 2 . ~ ' : . - - < [ ~"
F0F ~ stairwfll pressurization system that has not been designed to
a c c o m m o d a t e the o o e n i n ~ of doors, nressurization will d r o p when
ally d99rs open. a n d ~mol~e mav infiltrate the stairwell. For-a
buildin~ of low occupant density, the onenin~ and closin~ of a few
doors during evacuation will have little e f f e c t o n the system. For a
• building with a high occupant densitv a n d total building
¢vacuation. it can be exnected that most o f the doors will be onen
at som¢ time qiuring evacuation. The m e t h o d s nrovided in
ASHRAE/SFPE. Desia-a of Smot~, Management S~steras. can be used
to desima systems to accommodate anywhere from a few onen
doors go almgsr all ~ e door8 being onen. T h e effect of ooenin~ a
door g9 the outside is usually m u d a greater than that of oneninginterior doors. W h e n systems are designed for onen doors andtotal building evacuation, the n u m b e r o f oven doors needs to
include the exterior stairwell door.
In Figt ~i~.~.2.1~ the smoke zone is indicated by a minus sign and
:d~'~
are indicated by a plus sign. Each floor can be
:ol ~ r zone as in (a) and (h), or a smoke zone can
~ . ~ e than one floor as in (c) and (d). All the
~,zones in a building could be pressurized as in (a) and
fly, n o u s m o k e zones adjacent to the smoke zone could be
~d as in (b) a n d (d). A smoke zone can also be limited
of a floor as in (e).
.~:#~iii
2-4 Elevator Smoke Control.
2-4.1 Historically, elevator hoistways have proved to b ~ _ ~
~i y~{.}.'i:.:.~
available conduit for the m o v e m e n t of smoke throughSut :!.5: }.x~-~"
buildings. This is because the elevator doors have R.~ t.beer {$~ii~.~}:.
tightfittmg a n d elevat°r h°istways have been Pr~'~"" ~ ";
t~
~!
openings in their tops. The building stack e f f ~ has ~
:1 t ~
driving force that has readily moved s m o k % ~ , a n d ~
le ;.-':!
loosely constructed elevator hoistways. S ~ g e t h ~
:Is of~
correcting this problem have been p r o p o s e d a ~ ] ~ y , ttigati
~:2.i$'
?.:.
..4
These m e t h o d s include the following:
-%~
i.'2-5.2.2 In the event of a fire, pressure differences a n d airflows
p r o d u c e d by mechanical fans can be used to limit the smoke
spread to the zone in which the fire initiated. The concentration of
smoke in this smoke zone might r e n d e r it untenable. Accordingly,
in zoned smoke-control systems, building occupants should
evacuate the smoke zone as soon as possible after fire detection.
2-5.2.3_* Smoke-eomr-ot zones should be kept as small as
practicable so that evacuation from these zones can be readily
achieved a n d so that the quantity of air required to pressurize the
surrounding spaces will be kept to a manageable level. However,
these zones should be large e n o u g h so that heat buildup from the
fire will become sufficiently diluted with surrounding air so as to
prevent failure of major c o m p o n e n t s of the smoke control system.
(1) Exhaust of the fire floor
(2) Pressurization of e n c l o s e d elevator lobbies
(3) Construction of smoketight elevator lobbies
(4) Pressurization of the elevator hoistway
2-5.2.4 When a fire occurs, all of the n o n s m o k e zones in the buildin
can be pressurized as shown in Figure 2-5.2.1, parts (a), (c), and
(e). This system requires large quantities of outside air. The
c o m m e n t s c o n c e r n i n g location of supply air inlets o f pressurized
8=a2r:owc.~ s ~ e l l s
(see 2-3.3) also apply to the supply air inlets for
n o n s m o k e zones.
(5)* Closing of elevator doors after automatic recall
2-4.2 The m e t h o d s listed in 2-4.1(1) t h r o u g h (5) have been
employed either singly or in combination. However, their
application to a particular project, including the effect o f any vents
in the elevator hoistway, should be closely evaluated. The o p e n
vent at the top of the elevator hoistway may have an undesirable
effect on elevator smoke-control systems.
2-5.2.5 In cold climates, the introduction of large quantities o f
outside air can cause serious damage to building systems.
Therefore, serious consideration should be given to emergency
preheat systems that will t e m p e r the incoming air a n d help to avoid
or limit damage. Alternatively, pressurizing only those zones
immediately adjacent to the smoke zones could limit the quantity
o f outside air required, as in Figure 2-5.2.1, parts (b) and (d);
24.3_* Fires have shown the t e n d e n c y of smoke to migrate into
elevator hoistways. Therefore, the use o f elevators for egress
purposes has n o t been favored . . . . . . . . . . . . . . . :. . . . .
~ . . . . . . . ;_~ w
D
General.
. . . . . .
I~
. . . . . . .
.I . . . . .
.4 . . . . . .
.^
gm__c - u . :..g d . . . . Research has shown that use of an elevator
durin~ a fire is feasible provided the elevator system is nrotected
aeainst heat. flame, smoke, loss of electrical t3ower, loss of elevator
machine room cooline, water intrusion, and-inadvertent activi~ti011
of controls.
2-5 Z o n e d S m o k e Control.
594
NFPA
L
+
+
+
(a)
-
-
MAY
2000
ROP
can be pressurized stairwells that are also c o n n e c t e d to t h e area of
+
Smoke
}
92A
zone
An e x a m p l e of a simnle system is w h e n t h e r e are onlv nressurized
Ct~rwells in t h e building. Even t h e n . t h e interaction between
stairwells t h r o u g h t h e b-uildint,, oarticularlv w h e n doors are o n e n e d
a n d closed, m u s t be considered.
+
(b)
Often these systems are d e s i g n e d i n d e o e n d e n f l v to onerate u n d e r
t h e d y n a m i c forces they will e n c o u n t e r (for examole, buoyancy.
stack effect, wind). O n c e t h e design is comnleteci, it is necessary to
~tudy t h e i m n a c t t h e smoke-control system(s) will have o n each
other. For example, a n e x h a u s t e d s m o k e zone operating in
c o n j u n c t i o n with a stairwell pressurization system can t e n d to
improve t h e p e r f o r m a n c e of t h e stair pressurization system. At the
same time, it could increase t h e pressure difference across the
door, causing difficulty in o p e n i n g t h e d o o r into t h e
stairwell. For c o m o l e x systems, it is r e c o m m e n d e d that a network
mgdel, s u c h as those discussed in C h a n t e r 4. be used for t h e
4"
+
+
+
+
+
Smoke
zone
{
+
+
+
am!z~
+
+
+
2-6 7,~ Fire Floor Exhaust. E x h a u s t i n g t h e fire floor can imnrove
(c)
(d)
+
+
+
+
+
_
+
+
+
+
+
+
} Smoke
zone
(el
3 Building Equipment and Controls
A r r a n g e m e n t s o f s m o k e < o n t r o l zones.
F i g u r e 2-5.2.1
however, t h e disadvantage of this limited a p p r o a c h is that it is
possible to have s m o k e flow t h r o u g h shafts past the pressurized
zone a n d into u n p r e s s u r i z e d spaces. W h e n this alternative is ....~.:~.:~
considered, a careful e x a m i n a t i o n of t h e potential s m o k e f
involved n e e d s to be a c c o m p l i s h e d a n d d e t e r m i n e d a c c e ~
~"'%
~;:~
' " ~L
2-5.2.6 Signals f r o m pr:;tccd-'c z'g==ar::g fire a l u m s y s ' ~
u s e d to activate t h e a p p r o p r i a t e z o n e d smoke-control syste
~.~e~,~
~.
the alarm zones be a r r a n g e d to coincide with.....~'e s m ~
zones so as to avoid acavation of the ~ o n g ~ o k e - c o n t r ~ i
• 0,7
system(s).
i
-%::..~::.
•
.
"" ~ . . . ' . . " ' "
____" _ With s o m e modification,
~ b m ' l d ' m g
H V A C c q u l p m c : : systems can be u s e d to
~i~ovide:~uilding s m o k e control. Various types o f building
i ~ l u j p m e n t are discussed in this chapter; however, it is impractical
t~ver
all types. This c h a p t e r provides g e n e r a l i n f o r m a u o n on
~ u i p m e n t a n d controls a n d provides guidelines that can be used
~o a d a p t t h e majority o f systems e n c o u n t e r e d •
3-2 Heating, V e n t i l a t i n g , a n d Air-Conditioning (HVAC)
Equipment.
3-2.1 General. Heating, ventilating, a n d air-conditioning (HVAC)
cqu'Fmczt.%~te_[~ normally provide a m e a n s of supplying,
returning, a n d e x h a u s t i n g air f r o m a c o n d i t i o n e d space. T h e
HVAC e q u i p m e n t can be located within t h e c o n d i t i o n e d space,
within a d j a c e n t spaces, or within r e m o t e m e c h a n i c a l e q u i p m e n t
rooms. Most HVAC eq-!F.-'..ent Systems in buildings w h e r e s m o k e
control is considered can be a d a p t e d for z o n e d s m o k e control.
. ~a&<-'k
2-5.2.7 Unless venting or e x h a u s t Is p r o w d e d m t-~.i~re z ~ ,
the
pressure differences will n o t be developed a n d e v e ~ r e s s u r e
equalization between t h e fire zone a n d t h e u n a f f e c t e ~
Les will
b e c o m e established and t h e r e will be n o t h i n g to ~ , ~ j ~
s m o k e spread into all the zones.
2-6" Areas o f Refu~e. Smoke control for areas of refu~e can be
provided by pressurization. For areas of refu~e adiacent to
stairwells or elevators, provisions n e e d to be m a d e - t o p r e v e n t loss
of pressure 0r ¢~¢eessive pressures d u e to t h e interaction o f the area
9;[ r e f u ~ s m o k e control a n d t h e shaft s m o k e control.
3-2.2 ~
It is necessary to have the capability of
providing a d e q u a t e outside air for supply so t h a t sufficient
d:~ffcrcnd~2 prcz~ure;'. ~
can be achieved across
to ~
~
migration of s m o k e into uninvolved
areas. Mechanical e x h a u s t to t h e outside f r o m t h e s m o k e zone is
also necessary. Some HVAC systems have this capab!lity without a
n e e d for modification. W h e n supply a n d r e t u r n are i n t e r c o n n e c t e d
as part of n o r m a l HVAC operation, s m o k e d a m p e r s n e e d to be
provided for separating t h e supply a n d e x h a u s t d u r i n g smokecontrol operation.
2-67 C o m b i n a t i o n o f Systems.
2-67.1 General. T h e r e m l g ~ - b e a r e occasions w h e n
. . . . . . . . n . . . . . ~, ~.~., . . . . . . .
m o r e t h a n o n e smoke-control system
; ' - ' ~ Frc~zur'zed ::z2rtcwerc will be o n e r a d n g simultaneously.
3-2.3 HVAC Air-Handlin~ Svstem Types. Various types a n d
a r r a n g e m e n t s o f air-hand'ling systems are c o m m o n l y u s e d in
different types of buildings. S o m e types are m o r e readilv adantible
for s m o k e control avnlications t h a n others. T h e following are
e x a m p l e s of typical air-handling systems.
t~ t~e "~=errel='-c~ ~f the ccmpe.'=e=t :)-.te:n..=. !t .~..'g~t = c t be
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
~
o 7 . . . . . . . . . . . . . . . . . .
v
.
.
.
.
.
indzpzndent z;~'.cn-..~ zz:d cc..'nSinc "..Scmta. =zh!z':c .%;'::r'.zz.5!e
.~. .-. .-. '. -. .:. .-. -. .,. ;
For example, pressurized ~tairwells can
Ihat are Dart of a zoned
smoke-control
System. ~[evator hoist~ays that are Dart of a n elevator smokecontrol system can c o n n e c t to floor areas that are hart of a z o n e d
smoke-cootrol svstem. T h e elevator smoke-control system can be
c o n n e c t e d to areas of retiree t h a t in t u r n are c o n n e c t e d with floor
areas ~ha~ ~r~; part of a zoned smoke-control system. Further. t h e r e
connect
. . . . . .!. ... . . . . .
to floor
areas
$-2.3.1 Individual Floor I d s i ~ y r f l ~ / l l ~ . Individual air-handling
units serving_ o n e floor or part of a floor are a c o m m o n design
approach. T h e s e HVAC units m i g h t or m i g h t n o t have separate
r e t u r n / e x h a u s t fans. W h e r e t h e s e fans are n o t senarate, a m e a n s
fgl" providing relief of t h e fire floor pressures s h o u l d be investigated
either t h r o u g h relief d a m n e r s on t h e d u c t system or other means.
595
NFPA 9 2 A -
MAY 2000 ROP
.^__:_~ _At.. . . . . . . _..:. . . . . other sources of heating (e.g.,
baseboard or cabinet heaters).
Outdoor air can be supplied to each air-handling unit via one of
the following:
VAV systems vary the quantity of cold air supplied to the occupied
space based on actual space demands. Some VAV systems bypass
supply air to the return air inlet of the fan, reducing supply air
volumes and resultant pressure to avoid fan or ductwork damage.
In the smoke-control mode, such bypasses must he closed. For
smoke control, the speed of the VAV system ~
fan (s) should
be increased and VAV terminal unit controls should be configured
to open the terminals in the non-smoke zone to supply maximum
volume of outside air to pressurize spaces if sufficient air is
available. Bypass dampers 9n svstems usin~ this method need to
be closed. It is possible to achieve smoke control with the VAV
system supplying minimal air, but care must be taken to ensure that
adequate pressure is developed in the space.
(1) Exterior louvers and dampers
(2) A common duct system sized to handle the reouired
quantities of air
(3) A common duct systerrl having a variable-speed supply fan
(~)
Individual variable-speed supply fans.
Air-handling units can be used for smoke control if sufficient
outside air and exhaust air capability is available.
3-2.3.2 Central Systems. Some buildings utilize centralized HVAC
equipment in main mechanical areas that serve multiple floors
within the building. I-[VAC systems of this type might require fire
and smoke shaft dampering to provide exhaust of the fire floor and
pressurization of the adjacent floors with outside air. Because
these central fans can be of large capacity, care must be taken in
designing systems to include a means of avoiding excessive
pressures within the duct system to prevent rupture, collapse, or
other damage. Means need to be provided to control pressures
within exits and corridors that could inhibit doors from being
opened or closed.
3-2.3.7 Fan-Powered Terminal t~.ILS&~al~. S~mz -.-..~'=5!c ^-= ";~!'-:mc
i;._.^m[~
....
.t~ . . . . . .
~'~.
^17 .^1~1
.." . . . . . .
I:-.i
~A
a7. . . . . . . . . .
A
co=::ant ".'ol'amc t c ~ ' n ^ 2 u~"~. Thczz tc:~,Jnal "'='~ czn=i=t of a
~.'~ he~fing cc'~ "~= =.c2nWA: the d¢~'rz~ =p=z¢ tzmpz~turz.
In
3-2.3.3 Fan/Coil Units and Water Source Heat Pump Units.
Fan/coil and water source heat pump types of air-handling units
are often located around the perimeter of a building floor to
condition the perimeter zones. They may also be nrovided
throughout the entire floor area to nrovide the total airconditioning system. Because the (an/coil and water source heat
pump units are comparatively small in outside air capacity and are
typically difficult to reconfigure for smoke-control purposes, they
ca.': bc cxc!udz~ f;om are g~nerally not s~itable for performing
smoke-control functions. If these units have outside air intake
provisions, such units within the smoke zone should be shut down
when the zone is to be negatively pressurized.
. ~ . 3 . 8 :Mixed Systems. Combinations of the examples described
~.'. 3-J2.3.1 through 3-2.3.7 are sometimes used, especially for
l~.'i[iffing areas being altered for use other than originally intended.
~ - e must be exercised in the application of different
~
L~-e-s-~ variable volume systems-~ terminal units to
their effect on zoned smoke control. Designs must be
based on the capability of system configurations to achieve positive
or negadve pressures as needed for smoke control.
The fan/coil and water source heat pump units are typic..~.~ .
in combination with larger central HVAC equipment o~kiividu..~:
interior zone air-handling units. The zone smoke-cor~?..::~ ~,..?:
functionality should be provided by the larger central /Sr i ~ . : ~ .....
zone air-handling units.
A~¢~:-:-:-. :::~ ~::"
3-2.3.4 Induction ~
t_~.Lg.m~,
S
lnducfion-~" air-~g
lLIrit~'~il
located around the perimeter of a b u i l d i n g , : ~ : p r i m ~
t,~.-';~I.:':~"
condition the perimeter zone of older m u l ' ~ f i s ~ . . . t ~ c t u r e d ~
central HVAC system supplies high-pressure h e ~ . . o r coo.l~d air
to each perimeter induction unit. Room air is t h ' ~ d u ~ a
into
the induction unit, mixed with the primary air from ~..~'entral
HVAC system, and discharged into the room.
~i.:--v
3-2.4 Ventilation Systems. In certain instances, specialized systems
with no outside air are used for primary cooling and heating.
These systems include serf-contained air conditioners, radiant
panel systems, and computer room units. Because these systems
provid¢ no outside air. thev are not suitable for smoke contrgl
anDlication.
Induction units within the smoke zone should be shut down or
should have the primary air closed off on initiation of smoke
control iO smoke zones.
Because building codes require ventilation for all occupied
locations, a separate system for providing outside air is needed.
:~-t,AsThe system supplying outside air can be used for smoke
control although the quantity of air provided might not be
adequate for full pressurization.
3-2.3.5 Dual Duct and Multizone Systems. HVAC units used in
dual duct and multizone systems have cooling and heating coils in
them, each in a separate compartment or deck within the unit.
3-2.5 Special-Use Systems. Laboratories, animal facilities, hospital
facilities, and other unusual occupancies sometimes use oncethrough outdoor air systems to avoid contamination and could
have special filtration and pressurization requirements. These
special-use systems can be suitable for a smoke-control application.
Care needs to be exercised to avoid contamination of bacteria-free
areas, experiments, processes, and similar areas.
Dual duct systems have separate hot and cold ducts connected
between the decks and mixing boxes that mix the air supplied to
the space served. For high-pressure systems, the mixing boxes also
reduce the system pressure.
Multizone systems mix heated and cooled air at the unit and
supply the mixture through low-pressure ducts to each space.
3-3 Smoke Dampers. Smoke dampers used to protect openings in
smoke barriers or used as safety-related dampers in engineered
smoke-control systems should be classified and labeled in
accordance with UL 555S, Standard for Safety Leakage Rated Dampers
Smoke control should- can be achieved by supplying maximum air
to areas adjacent to the smoke zone. This should be accomplished
using the cold deck because it is usually sized to handle larger air
quantifies. For the smoke zone, supply fans should be shut off.
for Use in Smoke Control Systems.
3-2.3.6 Variable Air Volume (VAV) .Sys.tems. A- Variable air
volume (VAV) systems are either individual floor systenls (see
3-2.3.1 ) or centralized multi-floor systems (see 3-2.3.2l that are
orovided with terminal devices th~it typically s u p p l 2 i e ~
cooling only. Individual areas served by the system usually have
Dampers in smoke-control systems need to be evaluated for their
ability to operate under anticipated conditions of system operation.
3-4 Controls.
596
NFPA 92A
-
-
MAY 2000 R O P
3-4.1 Coordination. The control system should fully coordinate
smoke-control system functions a m o n g the fire ~rc.tccfi':¢ ;':gna"zg
alarm system sprinkler system fire fighters' smoke-control system
and any other related systems with HVAC and other building
smoke-control e q u i p m e n t .
capable of activation for smoke control, or a combination of these
ant)roaches. Diat,rams and ~ranhic renresentations o f the system
should be used: l~owever, they might n o t be necessary where
acceptable to the a~thority h~vingiurisdiction.
3-4.2 HVAC System ControLs.
3-~,$,4,2 The layoot labeling, and location of the FSCS should be
reviewed and at)t)roved bv the fire det)artment or fire official t)rior
to installation.
3-4.2.1 Operating controls of the HVAC system should be
designed or modified to accommodate the smoke-control mode,
which must have the highest priority over all other control modes.
3-4.3.4.$ The FSCS should have the highest priority control over all
smoke-control systems and equipment. Where manual controls for
control of smoke-control systems are also provided at other
building locations, the control m o d e selected from the FSC~
should prevail. FSCS control should override or bypass other
building controls su~:h as Hand-Off-Auto a n d Start/Stop switches
located on fan motor controllers, freeze detection devices, a n d
duct smoke detectors. ESC,S control should n o t ..... :a^ ^. ,.. . . . .
take p r e c e d e n c e over fire sunt)ression, electrical or nersonnel
t)rotection devices, a n d ccn2.r-~!: "~tcndcd to prqtcc-t vGzLnzt
3-4.2.2* Various types o f control systems are commonly used for
HVAC systems. These control systems utilize pneumatic, electric,
electronic, and programmable logic-based control units. All of
these control systems can be adapted to provide the necessary logic
a n d control sequences to configure HVAC systems for smoke
control. Programmable electronic logic-based (i.e.,
microprocessor-based) control units, which control and m o n i t o r
HVAC systems as well as provide other building control and
monitoring functions, are readily applicable for providing the
necessary logic and control sequences for an HVAC system's
smoke-control m o d e of ~peration.
- - - :
. . . . .
~ ^ - -
A . . . . .
']~I.^._
:---1..A
. . . . . . . . . . .
•
- - - - . - - - : ^ - -
3-4.3 Smoke-Control System Activation and Deactivation.
Smokecontrol system activation is the initiation of the operational mode
of a smoke-control system. Deactivation is the cessation of the
operational m o d e of the smoke-control system. Smoke-control
systems normally should be activated automatically;, however, u n d e r
certain circumstances, manual activation can be appropriate.
U n d e r either automatic or manual activation, the smoke-control
system should be capable of manual override.
capability n e e d not bypass Hand-Off-Auto
kcated on m o t o r controllers of
~ o l system fans, where t h e following
Based on the design arm intended performance o f the smokecontrol system, consideration should be given to the position (i.e.,
open or closed) of smoke dampers on loss of power and on
shutdown of the fan systems that the dampers serve.
only to W
~.(2 ) The
3-4.3.1 Automatic actigttion (or deactivation) includes all means
whereby a specific fire detection device or combination of devices
causes activation of one or m o r e smoke-control systems w i t h ~ . : : : .
manual intervention. For purposes of automatic activatio~fr~'%ili
detection devices include automatic devices such as sm~:.¢
~#"
detectors, waterflow switches, and heat detectors.
@";:::~.~&..-'-.{"~t
3-4.3.2_* Manual activation (or deactivation) c o v e ~ x ~ . m e a n
~.,
whereby an authorized person activates one o r . ~ / ~ : ~ = ~ e - cg'~
systems by means of controls provided for tls..~:-'."~urpose.'~
:'*'~'i:~
purposes of manual activation, the Iocatio~)...i...~te c o n t r o t ~
~;"
at a controlled device, at a local control p~ht~i~::,he builc~j~'s
main control center, or at the fire ~ " " ~
:::
-::.:::"
c o m m a n d station. The specific location(s) s h o ~ ~
iql'uired
~ a l l stations
by fire authority having.jurisdiction. Manual fire al
generally should n o t be used to activate smoke-con~4 .systems,
~thcr "hat: ~w2~'.vcr prczzur'z~fi~n z)'ztcm~ which reomre
information on the location of the fire to onerate, because of the
likelihood of a p e r s o n signaling an alarm from a station outside the
smok-~ zone of fire origin.
motor c m ~ o l l e r s are located in mechanical or
~ e n t rooms, or other areas generally accessible
i'ed personnel.
:.
such a m o t o r controller switch to turn a fan on
~ 4 y cause a n ".r~u~!z =nnunz'~.ficn off-normal
e building's main control center durin~ normal
ac'd;ntcd or =rc capab!c ~f acfi'.nfi~n for ~m~kc cvntr~' ~hou!d he
3-4.3.4.4 ~
status indication ( O N and OFF) should be
provided for ~n -~-.ndcff z~nva~ cf cach "~n~;~du~ dedicated smokecontrg] System fan and all nondedicated fans having a capacity in
..
excess of 2000 f t S / m i n (57 m S / m i n ) and used for smoke control.
ON status should be sensed by a pressure difference, an Mrflow
switch. ~ o r somt~ 9ther p r o o f o f airflow. | n d i r e c t indication of
fan status is n o t positive p r o o f of airflow. Additional indications
such as d a m p e r position can be provided where warranted b~' the
complexity of the system. Status indication need n o t be provided
for individual fans that are included in zoned control and
indications.
3-4.$.$* Response TLme. Smoke-control system activation should
be initiated immediately after receipt of an appropriate automatic
or manual activation command. Smoke-control systems should
activate individual c o m p o n e n t s (e.g., dampers, fans) in the
sequence necessary to prevent physical damage to the fans,
dampers, ducts, and other equipment. The total response time for
individual c o m p o n e n t s to achieve their desired state or operational
,node should not exceed the following time periods:
3-4.4 Controls for Stair Pressurization Systems. The criteria for
activation of stair pressurization systems should be as follows:
$-4.4.1 Automatic Activation. Operation of any zone of the
building prc.tccfive ~ignallng fire Marm system should cause all stair
pressurization fans to start. In limited instances, it can be desirable
to pressurize only some ztalrt~;-'erz ~
due to particular
building configurations and conditions. A smoke detector should
be provided in the air supply to the pressurized ~ % r t o - w e * s ~ i ~ e l l .
O n detection o f smoke, the supply fan(s) should be stopped.
(1) Fan operation at the desired state: 60 seconds
(2) Completion of d a m p e r travel: 75 seconds
3-4.3.4 Fire Fighters Smoke-Control Station (FSCS).
3-4.3.4.1 A fire fighters' smoke-control station (FSCS~ should be
t)rovided for all smoke-control systems. The firc fighter~' ~mc.kc
. . . . . . ' . . . . :. . . . .
rcqu!rcd, ~ C S should provide
mc.n!tc.-ng complete status indication and manual control
. . . . '-:':'-" ovcr of all smoke-control systems and equipment. Status
indicators and controls should be Iot,icaliv and clearly arranged
and labeled to convey dae i n t e n d e d svstem objectives to fire fi~hters
who may be unfamiliar with the system. Ot)e-rator controls sl~ould
be nrovided for each smoke-control zone. each niece of e o u i n m e n t
3-4.4.2 Manual Activation. A manual override switch should be
provided at the FSCS to restart the ~ s t a i ~ e l l
pressurization fan(s) after shutdown from the smoke detector, if it
m d e t e r m i n e d that a lesser hazard exists from smoke entering the
stairwell via the fan than smoke migrating into the
stairwell from adjoining snaces.
' ~ - ^
597
NFPA 92A ~
MAY 2000 ROP
3-4.5 Controls for Zoned Smoke-Control Systems.
automatic control accordin[g to building occupancy schedules,
energy m a n a g e m e n t strategtes, or other n o n e m e r g e n c y purposes,
such automatic control should be p r e e m p t e d or overridden by
manual activation or deactivation of the smoke-control equipment.
Manual controls provided specifically for this purpose should be
clearly marked as to the zone and function served. Manual
controls that are shared for both smoke-control functions and
o t h e r building control purposes, as in a building's main control
center, s h o u l d fully cover the smoke-control functionality in the
control center operational documentation.
3-4.5.1 The criteria for activation of z o n e d smoke-control systems
should be as follows:
(a) Automatic Activation. An automatic smoke detection system
can be used to automatically activate a z o n e d smoke-control
system. T h e smoke detection system can be of limited coverage
having spacing greater than 900 ft ~ (84 m 2 ) per detector, provaded
that the smoke detectors are so located as to detect smoke before it
leaves the smoke zone. The location of smoke detectors and the
zoning o f the detectors needs to be carefully analyzed to achieve a
smoke detection system that will reliably indicate the correct smoke
zone.
3-4.5.3 Sequence. Separate smoke-control systems should be
activated in a specific overall sequence to ensure maximum benefit
and minimize any damage or undesirable effects on ducts or
equipment.
Automatic actuation of a z o n e d smoke-control system, which is
designed to exhaust the fire area and supply air to other areas,
should be given careful consideration before being undertaken
because of the possibility of activation of a detector outside the
zone of fire origin.
3-4.5.4_* Schedule. Each different smoke-control system
configuration should be fully defined in a schedule format that
includes, but is n o t limited to, the following parameters:
(1) Fire zone in which a smoke-control system automatically
activates.
A waterflow switch or heat detector serving the smoke zone can be
used to activate the z o n e d smoke-control system where piping a n d
wiring of such devices coincide with the smoke-control zone.
(2) Type of signal that activates a smoke-control system, such as
sprinkler waterflow qf: smoke detector.
~W~r"~ic4"
(3) Smoke zo
e m a x i m u m mechanical exhaust to the
outside is i m p ~ ' ~ d d
and n o supply air is provided.
~ . . a n
(4) P o ~ i ~ . ~ a . o k e - c o n t r o l
zone(s) where m a x i m u m air
supply .,:::
i .....
S . - ~ ~ ~. ...~. +. ~, .-~e:x. h a u s t
to the outside is provided.
(b) Manual Activation. Manual activation and deactivation
control o f the stair pressurization systems should be provided at the
FSCS as well as at the building's control center. In addition, the
FSC,S should have the capability to override the automatic
shutdown of a stair pressurization fan u p o n smoke detection, in
accordance with the j u d g m e n t of the fire incident c o m m a n d e r ,
Zoned smoke-control systems should n o t be activated ~ o m
manual fire alarm boxes c o n n e c t e d to the building ~
gign=l'ng s}-gtcn.= fire alarm svstem. T h e r e is no assurance that the
manual fire alarm box is located in the smoke zone. These fire
alarm boxes can be used to cause doors in smoke barrier walls to
close prior to smoke control system activation.
(~(~....ON
as r e q ~ d
to i m p l e m e n t the smoke-control
s y ~ . u.,~...e-speed fans should he further n o t e d as FAST or
~%~,k~...M~
to ensure that the i n t e n d e d control configuration
is a c h i e v @ ~ t '
.:~;.-~.~
"~-~%-~-+::'~'~"
~-..'~:':i~..-,.
"~':'~"
,.;..-ii~:::@3-~....Fan( s ) ~ f F as required to i m p l e m e n t the smoke-control
Key-operated manual switches located within a smoke zone that
"~"'-"~-~ ' . ¢ - ' ~ 2
are clearly marked to identify their function can be used to ¢:..'.'.-:'i:'."~';.'i~::
~7)
~per(s)
OPEN where maximum airflow must be
manually activate the zone's smoke-control system. Where,a ' ~
'~hieved.
is provided, z o n e d smoke-control systems should be c a p ~ ! of ~i~!:
~!i-"::i::i~
~':"
b e m g manually activated from the FSCS by switches cl...~'~ a r .~. . . . . . . . "~::(-.~
'".... Damper(s) CLOSED where no airflow should take place.
to identify the zone a n d function. In addition, where/.he IS
.,n
. .g. ~':~:":'
-~':':"..~-.-~::
~:9.-'::.'::-::
is provided with a main control center, zoned sm.9.,.g.~...-..~....o..ntr,::::::~:::..
"" (9) Auxiliary functions may be required to achieve the smokesystems should also be capable of being to be ~ ~ t i
~i::.:-:':'::~...~:::: control system configuration or may be desirable in addition to
from the building's main control center.
..:#;....
~:~'-"i!
smoke control. Changes or override o f normal operation static
..::~--~::.
"~il:.-'!.::
pressure control set points should also be indicated if applicable.
Extreme care should be exercised when ~ J ~ [ : ~ a manu~'~ only
activation to ensure that suitably trained persori'~.]!t.are avai~ble 24
(10) Damper position at fan failure.
hours a day, 7 days a week. If this cannot be g u a ~ e d , : . ~
automatic system with manual backup should be us~:~-:!;?
3-4.5.5* Automatic Response to Multiple Signals. In the event
..:::::::.,
that signals are received from more than one smoke zone, the
5-4.5.23_ Sequence o f Control and Priorities. The a£~omatic a n d
system should continue automatic operation in the m o d e
manual activation (or deactivation) of zoned smoke-control
d e t e r m i n e d by the first signal received. However. systems designed
systems should be subject to the following sequences of control
for ooeration of multinle zones using only heat-activated detection
and priorities.
~ v i c e s can exnand the control stratetw to accommodate additional
zones, un to the limits of the mechanical system design.
(a) Automatic Activation. Automatic activation of systems and
equipment for zoned smoke control should have the highest
~-4.fi*_ Control System SuFcr-Afc.: Verification and
priority over all other sources of automatic control within the
Instrumentation. Every d e d l e a t e d smoke control system should
building. Where e q u i p m e n t used for smoke control is also used
have means of ensuring it will operate if ~ ~ .
The
for normal building operation, control of this e q u i p m e n t should
means a n d freouencv will vary according to the complexity and
be p r e e m p t e d or overridden as required for smoke control, q'his
importance of the system. Supc~A=!~n ~e'Acc: c"__
~. inc!udc the
e q u i p m e n t includes air s u p p l y / r e t u r n fans and dampers subject to
automatic control according to building occupancy schedules,
energy management, or other purposes. The following controls
,_, E n d tc e n d =upcp.==:=n cf ~-he -:-.r:ng, zq'-':Fmzat, . ~ A A ° . ~ . °
should not be automatically overridden:
(1) Static pressure high limits
(2) Duct smoke detectors on supply air systems
(b)
(b) Manual Activation and Deactivation. Manual activation or
deactivation of zoned smoke-control systems and e q u i p m e n t
should have priority over automatic activation of smoke-control
systems a n d equipment, as well as over all o t h e r sources of
automatic control within the building. Where e q u i p m e n t used for
zoned smoke control is subject to automatic activauon in response
to an alarm from an automatic fire detector of a
~
~
system, or where such e q u i p m e n t is subject to
~. -
. prc=cncc
. . . of ......
t- . . . . . :-. t, pc,=;'cr "2c,:-~-.~trcz-naof all circuit
~,t'~ Pc='~'.'e co:'~..'.~m.=dan of f=n ---cd;~don ~7 race.':= ~f duc=
~r=zzu=c, _-:'x'
. . . .....
. . , or =.q='-=lcz=t G===c=s "2".=t===~o::.~ tc !=~ of
598
NFPA 92A ~
MAY 2 0 0 0 R O P
4-3* Computer Network Model. A c o m n u t e r network m o d e l
1~" . . . . . . . . . . . .
1" . . . . . . . .
~
I:" . . . . . . . . . . . . . .
t" . . . . .
I
. . . . . . . . . . . . . .
provides a m e a n s to calculate t h e airflows a n d oressure differences
t h r o u g h o u t a b u i l d i n g in w h i c h a smoke-control system is
onerating. In a network o r o g r a m , a building is r e b r e s e n t e d by a
network o f soaces o r nodes, each at a snecifie oressure a n d
t e m n e r a t u r e . Air flows t h r o u g h leakage o a t h s f r o m regions of high
oressure to re~ions of low nressure. T h e s e leakage o a t h s are doors
a n d windows t~hat can be o o e n e d or closed. Leak-a~e can also
occur t h r o u g h Partitions. floors, a n d exterior walls ~ d roofs. See
ASH[~,E/SI?PI~. Des/p'n of Smoke Management S~stems. for a
discussion of t h e m e t h o d u s e d to c o m b i n e multiole leakage paths
into o[1¢ equiv'4]fnt path. T h e airflow t h r o u g h a leakage p a t h is a
function of the nressure difference across t h e leakage oath.
J
d a m p e r "t~c..;
'~
x~/
or ~;ca~3 Z7, appFc.p~at.c.
Other ~e',qce~
"
3-5 Energy M a n a g e m e n t . Energy m a n a g e m e n t systems, particularly
those that cycle supply, return, a n d e x h a u s t fans for energy
conservation, s h o u l d be overridden w h e n their control or
o p e r a t i o n is in conflict with a smoke-control m o d e . Because
s m o k e control is an a b n o r m a l b u t critical m o d e of operation, it
s h o u l d take priority over all energy m a n a g e m e n t a n d other
n o n e m e r g e n c y control m o d e s .
In network models, air f r o m outside t h e building can be
i n t r o d u c e d by a nressurization system into a n v b u i l d i n g soace, a n d
t h e building space can be e x h a u s t e d to the outside. T-his allows
simulation of stairwell nressurization, elevator shaft nressurization.
zoned s m o k e control a n d any o t h e r woe of smoke-control svstem.
T h e pressures "throughout t h e buildin~ a n d steady flow rates
t h r o u e h all t h e flow n a t h s are obtained by solvim} t h e airflow
network, i n c l u d i n g the driving forces s u c h as wind. the
3-6 Materials.
3-6.1 Materials used for systems providing s m o k e control s h o u l d
c o n f o r m to NFPA 90A, Standard for the Installation of AirConditioning and Ventilating Systems, a n d o t h e r applicable NFPA
documents.
3-6.2 Duct materials s h o u l d be selected a n d ducts s h o u l d be
designed to convey smoke, withstand additional pressure (both
positive a n d negative) by the supply a n d e x h a u s t fans w h e n
o p e r a t i n g in a smoke-control m o d e , a n d m a i n t a i n their structural
integrity d u r i n g t h e period for which the system s h o u l d operate.
3-6.3 Special high t e m p e r a t u r e ~fi~g~ f c r =:..c!'-c ex.hau:t fan= ;':i!!
........
,,.. i. . . . . . . . . . .
E o u i n m e n t including, b u t n o t limited to.
fans. du#t~, a n d b~lance d a m p e r s s h o u l d be suitable for their
i n t e n d e d use a n d t h e pr0b~b[e t e m n e r a t u r e s to which they m i g h t
be exposed.
. . . . . . . .
u = ~ = l
.
.
.
.
.
.
.
.
.
]
_
_
(4) Sm
3-7 Electric Services Installation.
)nd~/~Jons with low building leakage
conditions with low building leakage
m d i t i o n s with h i g h building leakage
conditions with h i g h b u i l d i n g leakage
3-7.1 All electrical installations s h o u l d m e e t the r e q u i r e m e n t s of
NFPA 70, National Elecbical Code*.
3-7.2 N o r m a l electrical power serving air-conditioning s y s ~ . ~
generally have sufficient reliability for n o n d e d i c a t e d zone~.~knok'~i,~
control systems.
:.~il~i..".-x ~{*:
":?":~
.::.".':i~~..[~.~#....:.
3-7.3 W h e t h e r or n o t ~ ~ L b . £
power ~
sh6i$~..:~..~e
considered for dodic-,ated smoke-control s y s t e m s . ~ . r
coi~.~_.
systems.
,:..4.". . . . . . . :":'.,.::::::::.:
~-~!.'~ ~':~::"<"
:.'".:J:.:'~:'.~
workmanshin, for examnle, h o w well a d o o r is fitted or h o w well
w¢'0,ther striooing is installed. Typical leakage areas of construction
cracks in walls a n d floors of commercial b u ~ d i n g s are listed in
4-6 Friction Losses in Shafts. Pressure losses d u e to friction of air
flgwing in stairwells are ~imilar to those of air flowing in ducts.
Friction loss data has b e e n d e v e l o n e d bv T a m u r a a n d Shaw (1976~
for Qpen a n d closed stair tread with various levels o f o c c u n a n t
4-2 Design Eouations. T h e eouations that can be u s e d for analysis
of pressurized-stairwells a n d elevator s m o k e control are based on
idealizations c o n c e r n i n ~ similar building leakage f r o m floor to
floor a n d n o leakas~e t h r o u g h floors. T h e s e e u u a t i o n s are provided
in ASHRAE/SFPE.-Desio'n of Smoke Manacement S~stems.
Chapter 45 Testing
4~-1 Introduction.
4 ~1.1_* Absence of a c o n s e n s u s a g r e e m e n t for a testing p r o c e d u r e
a n d a c c e p t a n c e criten~ historically has created n u m e r o u s
p r o b l e m s at t h e time of system acceptance, i n c l u d i n g delays in
o b t a i n i n g a certificate of occupancy.
It is r e c o m m e n d e d that t h e building owner a n d building designer
share their objectives a n d design criteria for s m o k e control with t h e
authority having jurisdiction at t h e p l a n n i n g stage of t h e project.
T h e design criteria s h o u l d include a p r o c e d u r e for acceptance
testing.
Contract d o c u m e n t s s h o u l d include operational a n d acceptance
testing p r o c e d u r e s so that all parties - - designers, installers,
o w n e r s a n d authorityLe_s, having jurisdiction - - have a clear
u n d e r s t a n d i n g of the system objectives a n d t h e testing procedure.
599
NFPA 92A ~
Table 4-5 Tvaical Leakmm Areas for Walls and
Commercial Buildin~,s
Constrg(tion Element
Exterior Buildin~ Walls
(includes construction cracks.
cracks around windows and
doors)
~
~
Loose ~
Very Loose ~
Stairwell Walls
(includes construction cracks,
but not cracks around
windows aod doors)
~
vAx.ed.Ag.C.
Loose ~
Floors
MAY 2 0 0 0 R O P
4~-2.2 Prior to testing, the party responsible for this testing should
verify completeness of building construction, including the
following architectural features:
of
(1) Shaft integrity
0.50 x 10~
(2) Firestopping
(3) Doors/closers
(4) Glazing
(5) Partitions and ceilings
4_5-2.3 The operational testing of each individual system
component should be performed as it is completed during
construction. These operational tests normally will be performed
by various trades before interconnection is made to integrate the
overall smoke-control system. It should be certified in writing that
each individual system component's installation is complete and
the component is functional. Each component test should be
individually documented, including such items as speed, voltage,
and amperage.
Elevator Shaft Walls
(includes construction cracks.
but n9~ cracks and gaps
around doors)
Floors
(includes construction cracks
and gaps around penetrations)
~
v~kWd:Ag~
4_5-2.4 Because smo~.~..~control systems are usually an integral part
of building o p e r a # ~ e m s ,
testing should include the following
subsystems to t h ~ t e n ' t ' h ' ~ a t they affect the operation of the smokecontrol s yst e rrg.'~:"~.
.~. .-~'
: .~".'i~i
. . ...."":~"-"
~ ,
.
(1) F i r e , a r m
system (See NFPA 72, Naturnal
~For a wall. the area ratio is the area of the leaka~,e through the
wail ¢[ivideO by the total wall area- For a floor, the area ratio is
the area of the leakage through the floor divided bv the total
area of the floor.
hValues based on measurements of Tamura and Shaw (1976).
Tamura and Wilson (1966). and Shaw. Reardon. and Cheung
~-Values based on measurements of Tamura and Wilson (1966)
and Tamura and Shaw (1976).
a-Values extranolated from average floor ti~hmess based on
range of tight_hess of other construction elements.
~-Val-ues based on measurements of Tamura and Shaw (1978).
~ ' . ' . ~ e r ~ . . . ~ nage m e ~ system
-::::. ,:,~-..-:-~:.~.~..:~,.~'.-:':'~?:.
:.:,:.:.
(3) B ' ~ g
management system
~ . c<~,(4) HVA
,.x-~
':i ( , ~ ~
equipment
~i~}i6i T~'~peratu re control system
%,,
:!~:" Power sources
(8) Standby power
(9) Automatic suppression systems
(10) Automatic operating doors and closers
(11) Dedicated smoke-control systems
(12) Nondedicated smoke-control systems
(13) Emergency elevator operation
measurement of nressure differences and door ooening forces
under the design conditions agreed on with the authority having
iurisdiction.
4~-$ Acceptance Testing.
4~-3.1 General. The intent of acceptance testing is to demonstrate
that the final integrated system installation complies with the
specified design and is functioning properly. One or more of the
following should be present to grant acceptance:
4_5-1.2" This chapter provides recommendations for the testing of
smoke-control systems. Each system should be tested against its
specific design criteria- The test procedures described herein have
been divided into the following three categories:
(1) Authority having jurisdiction
(1) Component systems testing
(2) Owner
(2) Acceptance testing
(3) Designer
(3) Periodic testing and maintenance
All documentation from operational testing should be available
for inspection.
4 ~ 2 Operational Testing.
4 ~ 3 . 2 Test Equipment. Equipment for acceptance testing should
be provided as follows:
4 ~2.1 General. The intent of operational testing is to establish
that the final installation complies with the specified design, is
functioning properly, and is ready for acceptance tesdng.
Responsibility for testing should be clearly defined prior to
operational testing.
(1) Calibrated instruments to read pressure difference
[differential pressure gauges, inclined water manometers, or
electronic manometer (instrument ranges 0-0.25 in. w.g. (0-62.5
Pa) and 0-0.50 in. w.g. (0-125 Pa) with 50 ft (15.2 m) of tubing)]
(2) Spring scale (fi:hc...-m:.n'= :c~-)-c.),
(3) Anemometer
6OO
NFPA 92A -- MAY 2000 ROP
(4) Flow-me~uring hood (optional)
(5) Door wedges
( t ~ ) Signs indicating that a test of the smoke-control system is in
progress and that doors must not be opened (or dosed)
( ~ ) Walkie-talkie radios to coordinate equipment operation and
data recording
4~-~.$ Testing Procedures. The acceptance testing should include
the following procedures, a n d such procedures should meet
~rovisions of the AssociateH Air Balance Council (AABC} and the
National Environmental ]~Izncin~ Bureau (N'EI~B~.
4~-$.$.1 Prior to beginning acceptance testing, all building
equipment should be placed in the normal operating mode,
including equipment that is not used to implement smoke control,
such as toilet exhaust, elevator shaft vents, elevator machine room
fans, and similar systems.
~rocedure for recording data throughout the entire test, such that
e~ ~ r w e l l
side of the doors will s l a y s be considered
as the re~erence point [0 ~/-i~-*iil,..R~, (0 ~ ) ]
a n d the
floor side of the doors will always have the pressure difference
value (positive if higher than the ~tsit.towe~ stairwell and negative
when less than the s m i i . t e w ~ i l ~ , K ) . Since the stsit~ew~
stairwell pressurization system is intended to produce a positive
pressure within the etaiemw~ stalrw~l, all negative pressure value~
recorded on the floor side of the doors are indicative of a potential
airflow ~ a . t h r , Jaail3tcK~.ime the floor.
4~-&4.2 Verify the proper activation of the s t a l ~ v ~ stai~ell
ressurization system(s) in response to all means of activation,
oth automatic a n d manual, as specified in the contract
documents. Where automatic activation is required in response to
alarm signals received from the building's p t ~ e t e e t i ~ ~ f l r e
alarm system, each separate alarm signal should be initiated to
ensure that proper automatic activation occurs.
~
4~-3.4.$ With the s t a i f t e w ~ s t a i ~ e l l pressurization system
activated, measure a n d record the pressure difference across each
~
~
door with all ~
doors dosed. ~ t h e
exterior door would normally be onen d u r t r ~ evacuation, it should
4~-3.$.2 Wind speed, direction, a n d outside temperature should
be recorded ee-~hKiIIg each test day.
4~-$.3.$ If standby power has been provided for the operation of
the smoke-control system, the acceptance testing should be
conducted while on both normal and standby power. Disconnect
the normal building power at the main sei'vice ~disconnect to
.
simulate true operating conditions in this mode.
grtth, the ~ a i ~ * ~
system
g a i l 3 S ~ preuurization
et
4~-3.3.4 The acceptance testing should include demonstrating that
the correct outputs are produced for a given input for each control
sequence specified. Consideration should be given to t h e
following control sequet~ces, so that the complete smoke-control
sequence is demonstrated:
(1) Normal mode
(2) Automatic smoke-control mode for first alarm
k
(3) Manual override of normal a n d a u t o m ~
modes
(4) Retom
tO
L
normal
f
4 ~,3~.~ It is acceptable to perform acceptance ~
fire
.v.'.-.~. . . . . . . . . . .~. .-.' - - o alarm system in conjunction w i d e . s m o k e control system. One or more device circuits on the ~re
s i g ~ J ~ ~ a r m system can initiate a single input signal to the
smoke-control system. Therefore, consideration should be given to
establishing the appropriate n u m b e r of !nitiating devices a n d
initiating device circuits to be operated to demonm'ate the smokecontrol system operation.
4~-S.$.6"_ Much can be accomplished to demonstrate smokecontrol system operation without resorting to d e m o m t r a t i o m that
use smoke or products that simulate smoke. Where the authority
havingjudsdlction requires such demonstrations, they should b e .
based on the objective ~itet.ia- of inhibitin~ smoke from mit,r-afinf
~rosm smoke ~ane boundaries m other areas, Test cJriteria h ~ e d
on the svstem's abifitV to remove smoke from an area are not
annrondat~ for z o n ~ ~tmoke=c_ontrol s y k e s . ~ n r ~ theJ~ ~wt~n~
al"e d ~ i t m e d for containment, not removal, of smoke.
"4~s.4.~;* With the smim~,~semwell pressurization system
activated, open the m i ~ a a L ~ f _ d ~ m . -:--~. . . . .~.
~ ......
used in the swtem desi_gn, e a e - ~ 4 i m e r a n d measure and record
the pressure difference across each remaining d o s e d
t h e pressure difference across each closed door, measure the force
necessary to open each door, using a sprlng-type scale. Use the
same procedure established in 4 ~ $ . 4 . 1 t o record data throughout
the entire test. The local code a n d contract documents'
requirements should be followed regarding the n u m b e r and
Ioc~tion of all doors that need to be opened for this test.
~k~.4.6- All nressure di~erences ~md door o n e n i ~ forces should be
documented. The results should d e m o m t r ~ e ~
the a~tem i i
funcfionln~ ~ronerlv. No oresmre d i ~ e r e n ~ ~ o u l d be-lem than
the minimum d ~ i ~ n r m r e diffm'encm in Table ~-2.1 or the
nressures mecified-in the desifn documents. Door o n e n l n f forces
should not exceed that allowed bY the bnildin~ code. -Any nortion
of the system not workin~ properly should b e renalred and
' "
4~-3.4 ~ a i ~ e ~ S m ~ e H
Pressurization Symems. This section
anolles where Stairwell nre~urlzation is the only smoke control
system in the building. -Where stairwell nre~udzation is used in
combinati0n with zoned smoke control.-refer to 5-$.8.
4~-3.4.1 With all building HVAC systems in normal operation,
measure a n d record t h e p r e m u r e difference across each
door while the door is closed. After recording the
pressure difference across the door, measure the force necessary to
open each door, using a spring-type scale. Establish a consistent
t"
•
5-3.4.7 Pre~urlzed stairwell ves'dbuies should be treat~l as a zone
in a zoned sm0ke-control s~tem.
4~-~.5 Zoned Smoke-Control System.
4~-&5.1 Verify the exact location of each smoke-control zone a n d
the door openings in the r - - . . . . . .
~
of each zone. If the
N F P A 9 2 A - - MAY 2 0 0 0 R O P
all elevator doors closed. If the elevator d o o r on the recall floor
would normally be o o e n d u r i n g system t)ressurization, it should be
onen during testing. The I-IVA~Csystem should be off unless the
rlgrmal m o d e is to-leave the HVAC system on during smokecontrol onerations.
plans do not specifically identify these zones and doors, the fire
Frctcc'.2:'c z ' E ~ ! : = g ~ a r m system in those zones might have to be
activated so that any doors magnetically held open will close and
identify the zone boundaries.
4~-3.5.2 Measure and record the pressure difference across all
smoke-control zones that divide a building floor. The
m e a s u r e m e n t s should be made while the HVAC systems serving the
floor's smoke zones are operating in their n o r m a l (nonsmokecontrol) mode. The m e a s u r e m e n t s should be made while all
smoke h a r d e r doors that separate the floor zones are dosed. O n e
m e a s u r e m e n t s h o u l d be made across each smoke barrier d o o r or
set of doors, a n d the data should clearly indicate the higher and
lower pressure sides of the doors.
5-3.6.1.3 Establish a consistent p r o c e d u r e for recording data
t h r o u g h o u t the entire test. s u c h ' t h a t the shaft side of the doors will
always be considered as the reference ooint l0 in. w.g. (0 Pa)l and
the floor side of the doors will always l~ave the nressure difference
Valq~ (oositive if higher than the shaft and net, ative when less than
~3.6.1.4 Since the hoistwav pressurization system is intended to
or0duce a nositive oressure ~ t h i n the hoistwav, all ne~cative
pressure va)ues recorded on the floor side of the doors are
irlOicative of a ootential airflow from the shaft to the floor•
4~-3.5.3 Verify the p r o p e r activation of each zoned smoke-control
system in response to all means of activation, both automatic and
manual, as specified in the contract documents. Where automatic
activation is required in response to alarm signals received from
the building's prctecr':e = ! g ~ : . ~ g ~
system, each separate
alarm signal should be initiated to ensure that p r o p e r automatic
activation of the correct zoned smoke-control system occurs. Verify
and record the p r o p e r operation of all fans, dampers, and related
e q u i p m e n t as outlined by the schedule(s) referenced in 3-4.5.4 for
each separate zoned smoke-control system.
4~-3.5.4 Simulate a fire alarm i n o u t to activate t t ~ all zoned
smoke-control systems that is, are-appropriate for each separate
smoke-control zone. Measure a n d record the pressure difference
across all smoke barrier_s d o o r ~ that separate the smoke zone from
adjacent zones. T h e m e a s u r e m e n t s should be made while all
smoke barrier doors that separate the smoke zone f r o m the other
zones are fully closed. O n e m e a s u r e m e n t should be made across
each smoke barrier d,oof- or set of ~mc,kc ~arrAcr doors, a n d the
data should clearly indicate the h i g h e r a n d lower pressure sides of
the doors ~r b~-r'~erg. Doors that have a tendency to o p e n slightly
due to the pressure difference should have one pressure
m e a s u r e m e n t made while held closed and a n o t h e r made while n o t
held closed.
~-$,{i.1.5 If the elevator oressurization system has been desit,n e d to
operate d u r i n g elevator movemenL the tests should be repeated
u n d e r these conditions.
et
5RI
se
tr
,.:~.:.::..:..
":'~!~iii:~
iii'i,
":iiii~i
4~-3.5.5 Continue to simulate fire alarm innuts to actlvate~i~i..>.~.
~:
the zoned smoke-control systems ~
~
~
make pressure difference m e a s u r e m e n t s as described ~"~...5...:4.~~~2~..-.i.~'*;~
Ensure that after testing a smoke zone's s m o k e - c o n t r o l " s y s t : ~ - . . - ~
difference should be less t h a n the m i n i m u m design nressure
the svstems are properly deactivated and the HV..A..~.:~ems "~~.,'-~.-.:'-.~
' .'~
differences in Table 2-2.1 or the pressures soecified in the design
involved are r e t u r n e d to their normal operatan~'~'i'fr~.i~:or t~%
;'
documents. Elevator lobby d o o r - o o e n i n g forces should not exceed
activating a n o t h e r zone's smoke-control s y s t ~ Also e ~ t h a ~
all controls necessary to prevent excessive ~ r e
differe'~.~,~""
that allowed by the building code. Any oortion of the svstem not
functional so as to prevent damage to dud~s ~ i ~ . ¢ l a t e d buil~ing
working nronerlv should be reoaired and retested.
equipment.
"%iiliiiii)ii~i::." .J'::"
5-3.7 Area o f Refu~e; An area of refuge should be treated as a
zone in a zoned smoke-control system. The tests outlined in 5-3.5
should be conducted.
v
functioning orooerlv. No nressure difference should be less than
the m i n i m u m design oressure differences in Table 2-2.1 or the
oressures snecified-in-the design documents. D o o r o p e n i n g forces
should n o t exceed that allowed bv the building code. Any o o r d o n
of the system n o t working properly should be renaired anti"
5-3.8
C o m b i n a t i o n o f S m o k e - C o n t r o l Systems.
5-3.8.1" Stairwell and Zoned S m o k e - C o n t r o l System. The stairwell
oressurization system should be considered as one zone in a zonfgl
smoke-control system. T h e tests outlined in 5-~.5 should be
conducted• In addition, the tests o u d i n e d in 5-8.4.5 t h r o u g h 53.4.5 should be conducted. All tests should be conducted with
both systems operating in resnonse to a simulated fire alarm inpqt,
5-3.6 Elevator S m o k e - C o n t r o l Systems.
5-3.6.1 Hoistwav Pressurization Systems. This section aDolies
where elevator hoistwav pressurization is the only smoke-control
system in the building. ~There elevator hoistwav nressurizadon is
used in combination with zoned smoke control, refer to section 5-
5-3.8.9 Area o f R e f u g e and Z o n e d S m o k e - C o n t r o l System. An
area of refuge should be treated as a separate zone in a zoned
smoke-control system. T h e tests outlined in 5-3.5 should be
conducted.
5-3.6.1.1 Verffv the n r o n e r activation of the elevator oressurization
system(s) in resnonse to all m e a n s of activation, botl~ autorqgti~;
and manual, as snecified in the contract documents. Where
automatic activation is reouired in response to alarm signals
received f r o m the building's fire alarm svstem, each seoarate alBrffl
signal should be initiatedto ensure that p r o p e r autom-~t,i~
activation occurs•
5-$.8.$ Elevator Pressurization and Z o n e d S m o k e - C o n t r o l System.
The elevator nressurization system should be considered as one
zone in a zoned smoke-control system. Each elevator lobby in an
enclosed elevator lobby oressurization system should be considered
as one zone in a zoned smoke-control system. T h e tests oqtliIle~ iB
5-3.5 should be conducted. In addition• the tests outlined in ~i.g.6.1 or 5-.g.6.~ or both should be conducted.
5-3.6.1.2 With the elevator nressurization system activated, measure
and record the oressure difference across each elevator d o o r with
602
N F P A 9 2 A - - MAY 2 0 0 0 R O P
/I ~
II 1
~
.
.
.
I
.
"-tiN^ + + . ^ + _ _ ^ + k ^ . . l
. . . . .
.I" . . . .
I....11.
. . .
:k^.l
4[~-4A Special arrangements might have to be made for the
introduction of large quantities of outside air into occupied areas
or computer centers when outside temperature a n d humidity
conditions are extreme. Since smoke-control systems override limit
controls, such as freezestats, tests should be conducted when
outside air conditions will n o t cause damage to e q u i p m e n t and
systems.
.I~^..I.,I
s)~tcrn..'z p c ~ c r r r ~ n c c . O ~ c r test .-nz',.~c.4,zb--vc ~zzn uzc~
h~:tc-c^2!)• in inz'^,~c= :':here "&c a ' - ' ~ c r ' ~ ' ha:'ngj'--zdaic'den
: . . . . . . .
+: . . . .
~ ^ :
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~.
.
.
.
..47 . . . . . . . . .
..I
+ I . . ^ : . . ~ I I A : ~
. . . .
m c a h a J af tca~ag : :m;":;: ma:=agcmcnt -;.:tom ": quea~cna~!e.
4 L$.2 v . . . .
+
~,+ v . . . . . p,^. ^r ^.~ . . . . . . . . .
~^~- .-.--. ,,-.... ,-^^-
Chapter~6 Referenced Publications
6-1 The following d o c u m e n t s or portions t h e r e o f are referenced
within this r e c o m m e n d e d practice a n d should be considered as
part of its recommendations. The edition indicated for each
referenced d o c u m e n t is the current edition as of the date of the
NFPA issuance of this r e c o m m e n d e d practice. Some of these
d o c u m e n t s might also be referenced in this r e c o m m e n d e d practice
for specific informational purposes and, therefore, are also listed
in A p p e n d i x B.
~^~* Ct:em!za! zmc!:c-test~,
x~z
IV, X*
W" .
[~\~k
D^--I
.
.
.
.
.
-'~:.--^
.
+^-++
~ A
+^.+.
4_5-3.g~ Testing Documentation. O n completion of acceptance
testing, a copy of all operational testing documentation should be
provided to the owner. This d o c u m e n t a t i o n should be available
for reference for periodic testing and maintenance.
r ~ - l . l NFPA Publications. National Fire Protection Association,
1 Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.
4_5-3.810 Owner's Manuals and Instruction. Information should
be provided to the owner that defines the operation and
m m n t e n a n c e of the system. Basic instruction on the operation of
the system should be piovided to the owner's representatives.
Since the owner can assume beneficial use of the smoke-control
system on completion of acceptance testing, this basic instruction
should be completed prior to acceptance testing.
NFPA 70, National Electrical Code*, 1999 edition.
NFPA 72, N a t i o n a ~ A l a r m Code, 1996 edition.
....-.--.-~.•..-..:..-...
NFPA 90A, S ~ r d f o ~ : ~ h e Installation of Air-Conditioning and
Ventilating $ 3 ~ . ~ . 0 . 9 edition.
~
NFPA 9 2 ~ . ~ d e
ke Mana~rement S~stems m Malls. Atria.
and La~8"::~:~]::~0()O e ~ ' : "
..:#;:'~ %,
~":"
N.....~.:'~.:..dO~!~ifeSafet~ ~"de* 2000 edition.
::" "~':-"iiii~!~i.-ff~@~..-'
~.
..• - '
NFPJ[:~?..:Guidefor Smoke and Heat Venting, 1998 edition.
4_5-3.011 Partial Occupancy. Acceptance testing should be
performed as a single step when obtaining a certificate of
occupancy. However, if the building is to be completed or
occupied in stages, multiple acceptance tests can be conducted in
order to obtain temporary certificates of occupancy.
4_5-3.4012 Modifications. All operational and acceptance testang
~T'..'~i~i~::.-,NFPA
2001":.'::~"~dard on Clean A~rent Fire Extinguishing Systems.
should be p e r f o r m e d on the applicable part of the system whenever ~li~':!:j'~edition,~y"
the system is c h a n g e d or modified. Documentation should be
"~.~• :~:~::#:'~:ii~ii.::':~::.,.:#"
u p d a t e d to reflect these changes or modificauons
..........
.-.
......:
..
•
" "
.........
"%::~'nwke~overnent
and Control in High-Rise Buildings, 1994 edition.
4_5-4 Periodic Testing.
+.:-~iii;:::
"%i
~ . . ~ ' 2 Other Publications.
-..i'-'~ii#:'::.. .-:ig..:.::,~.,~. % .#ii::"
4_5-4.1 During the life of the budding, maintenance l § " e f f ~ - ~ + ' : ' : : : ? , : ~ b # ~ ~ l . 2 . 1 ASHRAE Publication. American Society of Heating,
ensure. that the
system
its intenct'~:i.
"::'.'.'.:.'.::.~:"
•
. a n .d Air C
. o n d m. o n m g. Engineers
.
.Inc., 1791 Tulhe
. smoke-control
.
.
. . . will . perform
.
,<.:..
..~,,.,^~
:.
Refrigeraung_
funcUon u n d e r fire c o n d m o n s . Vroper m m n t e n ~ - ~ i : f l a e s ~
...
Circle N/17 h.tl~nt~ CA ~()g9Q-99,f)P~
should, as a minimum, include the periodic t # n g o"+'--¥~f.~i, :':"~i~fi~?!';':;::
' .......................
e q u i p m e n t such as initiating devices, fans, ~ p e r s ,
co/:i~,
~"
~ q r a o ~ P / S ~ ~ E Oesi~',,oeSmoke Manw, ement ~stems 1999.
doors, and windows. Tae e q u i p m e n t s h o ~ : : . m a i n t a i n ' ~ i i i n
.
.
.
.
.
.
.
.
.
.
.
.
.
.
er's r e c o m
mm
m(e ~ . o n s .
( ~ N FNFPA
P
tg
accordance with the manufacturer's
6-1.2.2 SFPE Publication. Society of Fire Protection Engineers.
~ating
90A, Standard for the lru+tallation of A i r - C o n d i t i o n i•".~~:~'d.:.i.%V
7315 Wisconsin Avenue. Suite 1225W. Bethesda. MD 20814.
. .#..'.-
Systems, for suggested maintenance practices.)
Handbook of Fire Protection En~neering. 1995.
4 ~4.2 This section describes the tests that should b~:Yperformed
on a periodic basis to d e t e r m i n e that the installed systems continue
to operate in accordance with the approved design.
control system or the zone boundaries have been modified since
the last test. accentance testing should be conducted on the
portion modified.
~;~1.2.83 UL Publications. Underwriters Laboratories Inc., 333
Pfingsten Road, Northbrook, IL 60062.
UL 555, Standard for Safety Fire Dampers, 1999.
UL 555S, Standard for Safe~3 Leakage Rated Dampers for Use in Smoke
Control Systems, 1999.
4~-4.3 The system should be tested in accordance with the
following schedule by persons who are thoroughly knowledgeable
in the operation, testing, and maintenance of the smoke-control
systems. The results of the tests should be d o c u m e n t e d in the
operations a n d maintenance log and made available for inspection.
Any portion of the system not functioning in accordance with the
original desima should be repaired immediately and the system
6-I.3 Additional Publications.
Achakii. G.Y. and Tamura. G.T.. Pressure Dron Characteristics of
Typ.i c ~ Stairshafts in High-Rise Buildings. ASI~RAE Transactions.
American Society of Heating. Refrigerating a n d Air Conditioning
Engineers. Atlanta, GA~ Volume 94. Partl. 1988. on. 1223-1236.
4~4.3.1 Dedicated Systems, A t L ~ t Semiannually. Operate the
smoke-control system for each control sequence in the current
design criteria and observe the operation of the correct outputs for
each given input. Tests should also be conducted u n d e r standby
power, if applicable.
Shaw• C.Y.. Reardon. I.T. and Cheung. M.S.. Changes in Air
Leakage Levels of Six Canadian Office Buildings. ASHRAE lournai.
American Society of Heating, Refrigerating ancl Air Conditioning
Engineers. Adanta. GA, 1993.
4_5-4.3.2 N o n d e d i c a t e d Systems, A t L ~ t Annually. Operate the
smoke-control system for each control sequence in the current
design criteria and observe the operation of the correct output for
each given input. Tests should also be conducted u n d e r standby
power, if applicable.
Tamura, G.T, a n d Shaw, C.Y., Studies on Exterior Wall Air
TiEhtne~ and Air Infiltration of Tall Buildings• ASHRAE
Transactions. American Society of Heating• Refrigeratin~ and Air
Conditioning Engineers• Atlanta• CA. Volume 82. Part 1~ 1976. riD+
_
603
-o
N F P A 92A - - MAY 2000 R O P
A-1-6.3 O n e source of data is ASHRAE Handbook of Fundamm~tals.
Chapter 26. Climatic Desitna Information. It is suggested that the
99,6 p e r c e n t heating dry bulb (DB) temnerature a n d the 0.4
per¢¢tat cooling DB-temperature be used as the winter and s u m m e r
4¢siwn condition, resnectivelv. It is also suggested that the 1
p e r c e n t extreme wind velocity be used as the design condition.
Where available, m o r e site-soecific data should be consulted.
Tamura. G.T. and Shaw. C.Y.. Air Leakage Data for the Design fo
Elevator and Stair Shaft Pressurization Svst-ems. ASHRAE
Transactions. American Societv o f Heating. Refrigerating and Air
Conditioning Engineers. Atlanta. GA. Volume 82[Part 2. 1976. pp.
Tamura. G.T. and Shaw. C.Y.. Exnerimental Studies of
Mechanical V e n t i n e f o r Smoke Control in Tall Office Buildinws.
ASHRAE Transactions. American Societv of Heating. Refrigerating
a n d Air Conditioning EnL,ineers. Atlanta. GA. Volume 86. #art 1.
1978. nn. 54-71.
A-l-7 The oerformance obiective o f automatic sorinlders installed
in accordance with NFPA 1-3. Standard for the ln;tallation of
Sprinkler S~stems. is to orovide fire control, which is defined as
follows; Limiting the size of a fire bv distribution o f water so as to
decrease the hea-t release rate and 0re-wet adjacent combustibles.
while controlling ceiling gas temneratures_ to avoid structural
damage. A limited n u m b e r of investiwatiom have b e e n undertaken
in which full-scale fire tests were c o n d u c t e d in which the snrinlder
system was challenged but nrovided the exnected level of
0erformance (Mad~zvkowsl~i. 1992 a n d L o u g h e e d et al.. 1994L
These investigations indicate that. for a fire control situation, the
heat release rate is limited but smoke can continue to be
produced. However. the temnerature of the smoke is r e d u c e d and
the oressure differences nrovi-ded in this d o c u m e n t for smoke
Tamura. G.T. and Wilson. A.G.. Pressure Differences for a NineStory Building as a Resutlt of ( ~ i m n e v Effect a n d Ventilation
SYstem Oneration. ASHRAE Transactions. American Society of
Heating. Refrigerating and Air Conditioning Entfineers. Atlanta.
GA. Volume 72. Part 1. 1966. nn. 180-189.
Appendix A Explanatory Material
Appendix A is not apart of the recommendations of this NFPA
document but is included for informational purposes only. This appendix
contains explanatory material, numbered to correspond with the
applicable text paragraphs.
A-I-4 Approved. The National Fire Protection Association does
n o t approve, inspect, or certify any installations, procedures,
equipment, or materials; n o r does it approve or evaluate testing
laboratories. In d e t e r m i n i n g the acceptability of installations,
procedures, equipment, or materials, the authority having
jurisdiction may base acceptance o n compliance with NFPA or
other appropriate standards. In the absence o f such standards,
said authority may require evidence of proper installation,
procedure, or use. The authority having jurisdiction may also refer
to the listings or labeling practices of an organization that is
c o n c e r n e d with p r o d u c t evaluations and is thus in a position to
d e t e r m i n e compliance with appropriate standards for the current
p r o d u c t i o n o f listed items.
~.~
,~
should be d e s i g n e d to maintain
differences u n d e r likely conditions
m i n i m u m design pressure differences
l e r e d spaces are values that will not be
:s o f h o t gases. The m e t h o d used to
-2.1 for nonsprinklered spaces is
are difference due to buoyancy of h o t
Ilowing equation:
~2-2.1
the
of"~
""
or wind.
obtain
AP=
A-l-4 Authority Having Jurisdiction. T h e phrase " a u t h g , h a v i ~
jurisdiction" is used in NFPA d o c u m e n t s in a b r o a d ~ "
,
jurisdictions a n d approval agencies vary, as do__their~ t e ~ ~ ~
responsibilities. Where public safety is primary, tt}.~.~ thol " ~
having jurisdiction may be a federal, state, loc,~l~
~
~"
d e p a r t m e n t or individual such as a fire chief; #i% •
~
a tire prevention bureau, labor d e p a r t m e n ~ . . h e : ~ t
"
building official; electrical inspector; or o m e ~ , f i r
start ~ry
authority. For insurance purposes, an msuran~ir~., :ctio !
department, rating bureau, or other insurance: d i ~ (
q :~.
representative may be the authority havingjurisdi(
?..~.~ many
circumstances, the property owner or his or her desi ti~tedagent
assumes the role of the authority having jurisdiction; : g o v e r n m e n t
installations, the c o m m a n d i n ~ officer or departmental official may
be the authority having jurisdiction.
7.64
1
1
To
Tr
h
A P = pressure difference d u e to buoyancy of h o t gases (in. w.g.)
7", = absolute temperature o f surroundings in (°R)
T F = absolute temperature o f h o t gases in (°R)
h = distance above neutral plane (ft)
The neutral plane is a horizontal plane between the fire space a n d
a surrounding space at which t h e pressure difference between the
fire space and the surrounding space is zero. For Table 2-2.1, h
was conservatively selected at two-thirds o f the floor to ceiling
height, the temperature o f the surroundings was selected at 70°F
(20°C), the temperature of the h o t ~ases was selected at 1700°F
(927°C), a n d a safety factor o f 0.03 m. w.g. (7.5 Pa)was used.
A-l-~i,3 Airflow can be used to limit smoke migration when doors
in smoke-control barriers are ooen. T h e desima velocity t h r o u g h
an onen d o o r should be sufficient to limit smoke back_flow during
building evacuation. It should take into consideration the same
variables as used in the selection o f design nressure differences.
Design information is orovided in A S H I ~ / S F P E . Desiun of Smoke
Management S~stems.
For example, calculate the m i n i m u m design pressure difference
for a ceiling height of 12 ft as follows:
7", = 70 + 460 = 530 °R
Tp = 1700 + 460 = 2160 °R
h = (12) 2/5 = 8 ft
From the above equation, A P = 0.087 in. w.g. Adding the safety
factor a n d r o u n d i n g off, the m i n i m u m design pressure difference is
0.12 in. w.g.
While airflow can be used to inhibit smoke m o v e m e n t t h r o u g h a
space, the flow rates n e e d e d to nrevent smoke backflow are so large_
that there is concern about the a m o u n t of combustion air that is
sunnlied to the fire. W h e n airflow is used to manage smoke
movement, the flow o f air t h r o u g h the onenin~ into the smoke
zone must be of sufficient velocity to ore-vent smoke from leaving
th~,l; zgne through such ooenings. T h e air velocity necessary to
inhibit smoke m o v e m e n t t h r o u g h lartee onenings results in air
ouantities which are sufficient to sunoort-fire growth to
approximately 10 times the size c o m o a r e d to fire growth without
this additional airflow. More information on fire ~rowth can be
f o u n d in SFPE Fire Protection Handbook.
A-2-2.2 The forces on a d o o r in a smoke control system are
illustrated in Fitrure A-2-2.2. The force reouired to o n e n a door in
a smoke control system is
F=F~+
5.Z(WA)AP
2(W-
d)
where:
F = total d o o r o n e n i n g force fib)
F = force to overcome the door closer and other friction flb~
6O4
NFPA 92A ~
MAY 2000 ROP
W = d o o r width fit)
A = d o o r area (sq fO
A P = nressure difference across the d o o r fin. w.g.I
d = distance f r o m the d o o r k n o b to the knob s l d e o f the d o o r fit)
F
I
Knob/
,
A-3-4.2.2 The control system should be designed as simply as
possible to attain the required functionality. Complex controls, if
n o t properly designed and tested, can have a low level of reliability
and can be difficult to maintain.
Controls for nonsmoke control imrOoses. Manoal con~'ols
exclusively for o t h e r building control ournoses, such as Hand-OffAuto switches located on a thermostat, are not considered to I~e
manual controls in the context of smoke control. Manual
activation a n d deactivation for smoke control n u r n o s e s should
override manual controls for o t h e r ournoses.
Low-pressu
re
side
- ~i~//ll/llllll/ll/llllA~.:;_::::.N..::~:.:.:.~:::.$Ny.~:.:...-~x
t
~ p ~
HingeZ
Figure
A-2-2.2
a
A
Forces
on
a Door
in a Smoke
High-pressure
side
Control
Manual troll stations• Generally. stairwell pressurization systems
can be activated f r o m a manual null station, vrovided the resvonse
is c o m m o n for all zones• Other-systems that-resnond identically
for all zone alarms can also be activated from a mammal pull
station. An active-tracking stairwell pressurizatioa ~ystem that
nrovides control based o n t h e pressure m e a s u r e d at the fire floor
should n o t be activated f r o m a manual null station,
System.
.4.-3-4.3.3 Activation of the smoke-control system should occur
immediately after receint of the activation command, In order to
nrevent damage to etminment, it might be necessary ~o delay
activation of c e r t a i m " ~ v m e n t until o t h e r e u u i n m e n t has achieved
a vrereuuisite s t a ~ : t i . e f ~ e l a v starting a fan until its assodated
damuer-is n a r ~ . ' ~ f u l l v
ot~enL Tl~e times ~iven for comnonent,~
to achieve ~
d e s l ~ s t a t e - a r e m e a s u r e d f r o m the time each
~" ":÷"
"~Et"."~. .,,
comnonea~-'.,_~
z~-• vate~.}-.%~
A - ":''::if+...... ~ . . . . "~'z'~*~"
,~.4
~mple
o f a E..~ Fighters' Smoke-Control Station.
C~
for a fire Iighters ' smoke -control stauon
~ aU
" should
A-2-3.7 During the time that occuvants of the smoke zone ar¢
exiting the area. the conditions in the smoke zone are still
tenna[ale. Although o n e n i n g the stairwell d o o r on the fire floor
d u r i n g this time may release some smoke into the stairwell, it will
n o t create u n t e n n a b l e conditions in the stairwell. O n c e conditions
in the smoke zone become untennable, it is unlikely that the d o o r
"
to the fire floor would be o n e n e d bv occunants of that
floor. Fgr
this reason, it is normally n o t required to clesign for an open
stairwell d o o r on the fire floor. Doors blocked o v e n in violation of
annlicable codes are beyond the capability of the-system.
The• imnortance
of the.. exterior
. .De. mcatea
. . . m
- •
• stairwell d o o r can be exulained
.- .
.19Y ~:~.'~ "a"
t ) L om~a: r ~ . . . ~ " Access. -a"n e ~C,S
r~
s .n o. u m
considecauon of the conservauon of mass of the p r e s s u n z a u o n air,
~.~.;~miw
to l : ~ r fire fighters' systems as can be provided within
This air comes f r o m the outside a n d must eventually flow back to
% ~'~¢~.~[.in.~:~I.eans should be provided to ensure only authorized
the outside. For an o p e n interior door. the rest of the building 9n
~. a c ~ ' ~ .~ "
FSCS. Where acceptable to the authority having
that floor acts as flow resistance to the air flowing out the ooCn-,.:>.~.
~ i : i s d i c ~ " h , the FSCS should be provided within a specific location
doorway. W h e n the exterior d o o r is open. there-is no o t h ~
~ room, s e p ~ a t e d from pub!ic areas by a suitably marked a n d
c~ o o o. r • w n e r e locatecl in. a .separate
resistance, and the flow can be 10 to 30 times m o r e thart+."~rou~h~"
. . .~,~
. . . room,
. . . the r o o m
an onen
interinr
dnnr
~x{~..:~}..
- ~ . ~ .
~\l~taon,
size, access means anta o m e r pnysica~ uesign
--° ~-" . . . . . . . . . . . . . . . . . . .
" ':~::::~::~ -'::."':~>~:-q~- .:~; ~i '~"
.
.
.
.
'.:$..'.~...~.~.
$~:~,.:.-~- "~:~.-..~.'~onslderataons
should be acceptable to the authority
,:g$~?,.,.
. .
- - haxan~:
%':'::':~"-'::-
" '=+:""j u r l s d l c t l
on.
A-2-4.1(5) Rule 211.3a, Phase I Emergency R e c a l ~ t i o n ~ . ~
ASME/ANSI A17.1, Safety Code for Elevators a n ~ . . ~ g e q u + ~
:':
tb~ Physical Arran,,ement Th,~ ~SO-q sh,,,,~a h~ a ~ ; ~ , ~ a , ,
that elevator doors o p e n and remain o p e n . a ~ r the e l e ~
are .~6-'."
granhicallv depict
~
' ~l'"- : - ~ " . . the ~-~
~h"y slcal build:I l.l . . . ; t i l l an . .¢711
. . .I.¢ I I L ,
['1
~
recalled. This results in large openings i n . , ~
elevator ' ~ t w a ~ .
- -,
- ,
. . . . . "7 "~ .
. .
g
.
•
trreatlv
incroag~
the
a
l
r
f
l
.
w
r
e
n
n
~
d
~
n
r
e
.
~
n
r
i
¢
~
n
smote-control
systems
a
n
n
equipment,
anct
m
e
areas
9.LRIe
This can o . . . . ~ . . . . . . . . . . . . . . . . . . . . . . .
eta r~.~:i. . . . . . . ~ . . . . . .
NFPA 80, Standard [or $ire Doors and Fire W / n d o ~ r m i t s ~ o s i n g
~
served by the equipment. Following is a s u m m a r y of the
of elevator doors aider a n. r e d e t e. r m i n e.d time. w h e n < ~ i r . g ~~'"
t by, the
status indicators and smoke-control, capability applicable to the
authority having jurisdiction. Local requirements ~ r a t i o n
of
FSCS smoke-control graphic(s).
elevator doors should be determined and incorporat.~-into the
system design.
Status indicators should be provided for all smoke-control
e q u i p m e n t by pilot lamp-type indicators as follows:
A-2-4.3 T h e following references discuss research concerning
(1) Smoke-control fans and other critical operating e q u i p m e n t in
elevator use d u r i n g fire situations: Klote and Braun (1996); I~lote
the operating state: Green
(1995):
Klote. Levin and G r o n e r (1995): KIote• Levin and Gror~er
(1994): KIote (1993): Klote. Deal. Donoghue. Levin a n d ' G r o n e r
(1992): and Klote. Alvord, Levin and G r o n c r (1992).
(2) Smoke-control e q u i p m e n t a n d other critical e q u i p m e n t that
may have two or m o r e states or positions, such as dampers: Green
(i.e., OPEN), Yellow (i.e., CLOSED)
Design guidarlce on dilution temoerature is provided in
ASHRAE/SFPE. /)es/gn of Smoke Management S3stems,
A-2-5.2.$
T h e position of each piece of e q u i p m e n t should be indicated by
lamps a n d appropriate legends. Intermediate positions (i.e.,
modulating d a m p e r s that may n o t be fully o p e n or fully closed)
can be indicated by not illuminating either of their pilot lamps.
A-2-6 Methods of desimi for areas of refuge are presented in the
ASHRAE T r a n s a c t i o n s - r a p e r Desien of Smoke Control S~stems for
Areas of Refu~,e (Klote 1993).
(3) Smoke-control system or e q u i p m e n t faults: A m b e r / O r a n g e
605
NFPA 92A -- MAY 2000 ROP
Use-o~ T h e positions of multi-position control switches s h o u l d
n o t be u s e d to indicate the status of a controlled device z.~.eul~ : a t
be--used~ in lieu of pilot l a m p - t y p e status indicators as described in
A-3-4.3.4(1) t h r o u g h (3) above.
electrical d i s c o n n e c t switches, high-limit static n r e s s u r e switches.
a n d c o m b i n a t i o n f i r e / s m o k e d a m o e r s b e y o n d their d e m ' a d a t i o n
t e m n e r a t u r e classifications m e e t i n b U L 555. Standard for Safet~ Fire
Damt~ers. or U L 555S. Standard for Safet~ LeakatTe Rated Dam~e~s for
Use in Smoke Control S~stems.
Provision for testing t h e pilot lamps on t h e FSC,S smoke-control
panel(s) by m e a n s o f o n e or m o r e "LAMP TEST" m o m e n t a r y p u s h
b u t t o n s or o t h e r self-restoring m e a n s s h o u l d be included.
(2) A U T O . Only t h e A U T O position of each 3-position FSCS
control s h o u l d allow a u t o m a t i c or m a n u a l control action f r o m
o t h e r control points within t h e building. T h e A U T O position
s h o u l d be t h e n o r m a l , n o n e m e r g e n c y , building control position.
W h e n a n FSCS control is in t h e A U T O position, t h e actual status of
the device (on, off, o p e n , closed) s h o u l d c o n t i n u e to be indicated
by t h e status indicator(s).
(c) Smoke-Control Capability. T h e FSCS s h o u l d provide control
capability over all smoke-control system e q u i p m e n t or zones within
the b u i l d i n ~
W h e r e v e r nractical, it is r e c o m m e n d e d that control be provided
by zone. rather t h a n by individual e q u i p m e n t . T h i s a p p r o a c h will
aid fire fighters in readily u n d e r s t a n d i n g t h e ooeration of t h e
system, a n d will h e l n to avoid p r o b l e m s causeci bv m a n u a l l y
activating e o u i o m e n t in t h e w r o n g s e o u e n c e or neglecting tO
control a critic~al c o m n o n e n t . Control by zone s h o u l d b e
a c c o m n l i s h e d with P R E S S U R I Z E - A U T O ' E X H A U S T control:
control over each zone t h a t can be controlled as a, ~ingle entity,
Control o f this tvoe relies o n system p r o g r a m m i n g to properly
s e u u e n c e all dex;ices in t h e zone to n r o d u c e t h e desired effect. In
systems utilizing c o m m o n suoolv a n d / o r r e t u r n ducts, inclusion of
a n ISOLATE m o d e is desireable. To enable use of t h e system I;9
flush s m o k e o u t of a z o n e after t h e fire has b e e n extinguished, a
PURGE (eoual sunoiv a n d exhaust) m o d e m a y also be desireable.
(3) FSCS R e s p o n s e Time. For p u r p o s e s of s m o k e control, t h e
FSCS response time s h o u l d be t h e s a m e as for a u t o m a t i c or
m a n u a l smoke-control action initiated f r o m a n y o t h e r building
control point. (See 3-4.3.3.)
FSCS pilot lamp indication of t h e actual status of each piece of
e q u i p m e n t s h o u l d n o t exceed 15 s e c o n d s after o p e r a t i o n of the
respective feedback device.
(e) Graphic Depiction. T h e location of all- smoke-control systems
and eqmpment ~
b u i l d i n g sh_ould b e indicated by symbols
within t h e overall ~
~
" "
g r a n h i c panel.
~ ~ . ~ j o r
ducts, fans. a n d d a m p e r s
~lat a r e part':~4.he smoke-control system.
W h e r e control over individual nieces of e o u i n m e n t is d e e m e d
necessary, the following control o n t i o n s s h o u l d be provide~;
(1) ON-AUTO-OFF control over each individual piece of
o p e r a t i n g smoke-control e q u i p m e n t t h a t can also be controlled
f r o m o t h e r sources within t h e building. Controlled c o m p o n e n t s
i n c l u d e all stairway pressurization fans; s m o k e e x h a u s t fans; HVAC
supply, return, a n d e x h a u s t fans in excess of 2000 ftSmin (57
m / m i n ) ; elevator shaft fans; a t r i u m supply a n d e x h a u s t fans; a n d
a n y o t h e r o p e r a t i n g e q u i p m e n t used or i n t e n d e d for smoke-co
purposes.
~
:'-".~
smoke
~ol
(2) ON-OFF or OPEN-CLOSE control over all s m o g . :*" ..
a n d o t h e r critical e q u i p m e n t associated with a fire or ~ , , ~ , ~
e m e r g e n c y a n d that can only be controlled f r o m the FSCS
~:.:.:::::::::-:.~..
(3) OPEN-AUTO-CLOSE control over all i
relating to s m o k e control a n d that are also ~ t r o l l e d
sources within t h e building.
*:" "::~'~::"
fr~
for
s h o u l d be s h o w n o n the
)anel and, where appropriate, s h o u l d be
le~ d to their respective ducts, with a clear indication
,n o f airflow. In either case. t h e b u i l d i n g areas ~erv¢~
:!.
~':g""
system, a n d can be o m i t t e d w h e r e t h e i r inclusion would hint~gl"
u n d e r s t a n d i n g of t h e system, s u c h as on a n already densely
ooDulated oanel. DamDer nosition indication can also be omitted
where no seDarate control over d a m n e r r)osition is nrovided.
~:.-:.
~
~
,,~.~:...::,
r#;"
%!i"
(4) HVAC t e r m i n a l units, such as VAV m i x i n f f ~ . e s th~}~are all
located within a n d serve o n e d e s i g n a t e d s m o k e - c o ~ . ~ t $ e ,
can
be controlled collectively in lieu o f individually. ~ t n i t
coil
face bypass d a m p e r s that are so a r r a n g e d as n o t to r e ~ J c t overall
airflow within t h e system can be e x e m p t e d .
A-3-4.5.2 M a n u a l controls u s e d exclusively for o t h e r bqildin~
control o u r n o s e s , s u c h as Hand-Off-Auto switches located oq a
thermostat.-are n o t c o n s i d e r e d to be m a n u a l controls in t h e
c o n t e x t of s m o k e control. M a n u a l activation a n d deactivation for
s m o k e control n u r n o s e s s h o u l d override m a n u a l controls for o t h e r
Additional controls m i g h t be required by t h e authority having
jurisdiction.
A-3-4.5.4 Examples of auxiliary f u n c t i o n s that can be useful. I ~ t
are n o t reouired, are t h e o n e n i n g or closing of terminal boxes
while nressurizing or e x h a u s t i n g a s m o k e zone. T h e s e f u n c t i g n s
are considered auxiliary if the c/esired state is achieved without
these functions. T h e s e f u n c t i o n s can. however, held to achieve t h e
desired state m o r e readily.
(d) ControlAction and Priorities. T h e FSCS control action s h o u l d
be as follows:
(1) ON-OFF, OPEN-CLOSE. T h e s e control actions s h o u l d have
the h i g h e s t priority of any control p o i n t within t h e building. O n c e
issued f r o m t h e FSCS, n o a u t o m a t i c or m a n u a l control f r o m any
o t h e r control p o i n t within t h e building s h o u l d contradict the FSCS
control action.
A-3-4.5.5 D u r i n g a fire. it is likely that e n o u g h s m o k e to activate a
s m o k e detector m a y travel to o t h e r zones, a n d s u b s e a u e n t l v ~ u ~ e
alarm inputs for o t h e r zones. Systems activated bv s m o k e detectors
s h o u l d c o n t i n u e to operate a c c o r d i n g to t h e first alarm inpu~
received, rather t h a n diverting controls to r e s p o n d to any
subseouent alarm innut(s).
W h e r e a u t o m a t i c m e a n s are provided to i n t e r r u p t n o r m a l
n o n e m e r g e n c y e q u i p m e n t operation or p r o d u c e a specific result to
safeguard t h e building or e q u i p m e n t (e.g., d u c t freezestats, d u c t
s m o k e detectors, h i g h - t e m p e r a t u r e cutouts, t e m p e r a t u r e - a c t u a t e d
linkage, a n d similar devices), s u c h m e a n s s h o u l d be capable of
b e i n g overridden or reset to levels n o t e x c e e d i n g levels of i m m i n e n t
system failure, by the FSC,S control action, a n d t h e last control
action as indicated by each FSCS switch position s h o u l d prevail.
Systems initiated bv heat-activated devices, a n d d e s i g n e d with
su~:ficient canacitv to e x h a u s t multiole zones, can e x o a n d the
n u m b e r of zones b e i n g e x h a u s t e d to include t h e original zor~e and
s u b s e o u e n t additional zones, u o to t h e limit of the m e c h a n i c a l
system's ability to m a i n t a i n t h e design
oressure difference.
v
_
E x c e e d i n gy t h e design canacitv will likely result in t h e system failing
to adeouatelv e x h a u s t t h e fire zone so as to achieve t h e desired
Control actions issued f r o m t h e FSCS s h o u l d n o t 0vgrrid¢ or
bypass devices a n d controls i n t e n d e d to orotect against electrical
overloads, nrovide for n e r s o n n e l safetv, a n d n r e v e n t maior SYSt¢~
d a m a g e . T h e s e devices i n c l u d e o v e r c u r r e n t orotection-devices and
606
N F P A 9 2 A - - MAY 2 0 0 0 R O P
pressure differences. If the n u m b e r o f zones t h a t m a y be e x h a u s t e d
while still m a i n t a i n i n g t h e design n r e s s u r e is n o t known, this
n u r q b e r s h o u l d be ass~tlled to be one.
c o m n u t e r m o d e l d e v e l o n e d bv Walton (1997). CONTAM is a
sitmi'ficant i m n r o v e m e n t over ASCOS with resoect to b o t h n u m e r i c s
A-3-4.6 Verification devices can i n c l u d e t h e following:
Network c o m n u t e r m o d e l s s h o u l d be u s e d for t h e design of
smoke-control systems in c o m n l e x buildings for which tlae
algebraic e q u a t i o n s are n o t applicable or are imnractical to use.
This includes t h e analysis of stairwell nressurization systems with
o n e n doors, c o m b i n a t i o n smoke-control systems a n d smokecontrol systems in asymmetric buildings.
(1) End-to-end verification of t h e wiring, e o u i n m e n t , a n d devices
in a m a n n e r that includes nrovision for oositive c o n f i r m a t i o n of
activation, periodic testing, a n d m a n u a l - o v e r r i d e ooeration
(~) T h e preserlc¢ of ,?perating power d o w n s t r e a m of all circuit
disconnects
A-4-5 Leakage areas for exterior building walls have tvoicallv been
based on t h e m e a s u r e m e n t s of T a m u r a an-d Shaw (1975) a n d
T a m u r ~ a n d Wilson (1966). Recently. several buildings u s e d in the
p r e v i o ~ studies were retested after they were retrofitted for energy
efficiency (Shaw. R e a r d o n a n d C h e u n g 199$). T h e values for
leakage areas of exterior building walls were based o n this new
(3) Positive confirmation of fan activation bv m e a n s of d u c t
.°ressure- airflow, or equivalent s e n s o r s that r e s n o n d to loss o f
o n e r a t i n g power, probleg0s in t h e nower or control circuit wiring.
airflow restrictions, and failure of t h e belt, shaft counling, or m o t o r
A-5-1,1 Door o p e n i n g forces include frictional forces, t h e forces
o r o d u c e d bv the d o o r hardware, a n d the forces n r o d u c e d by the
smoke-control system. ' In cases w h e r e fritional f~rces are excessive.
(4) Positive c o n f i r m a t i o n of d a m n e r o n e r a t i o n bv contact.
proximity, or euuivalent sensors that r e s n o n d to loss of o n e r a t i n g
power or c o m p r e ~ g d air: p r o b l e m s in the nower, control circuit.
or o n e u m a t i c lines: a n d failure of t h e d a m n e r actuator, linkage, or
d a m n e r itself
A-4 ~-1.2 Whil
testing of b u ~
smoke z~;'~
testing
(~) Periodic acceotance testing in a c c o r d a n c e with C h a n t e r 5
(6) O t h e r devices or m e a n s as a n n r o n r i a t e
It¢r0s (1) t h r o u g h (6) describe multiole m e t h o d s that can be
usgd, either slnglv or it~ combination, to verify that all oortions of
t h e controls a n d e o u i p l B e n t are onerational. For examnle.
conventional (electrical) sunervlsion can be u s e d to ver{fv t h e
integrity of t h e c o n d u c t o r s f r o m a fire alarm system control unit to
t h e relay contact within $ feet o f t h e control system i n n u t (See
NFPA 72. National Fire Alarm Code °. Section 3-9). a n d end-to-end
,art o f t h e formal testing procedure, the
~..~letermine t h e a m o u n t of leakage between
~ue
in developing t h e initial system. T h e
sr:~p..~n
use existing airflow m e a s u r i n g
th~ms.
This section describes t h e
of ~ i e t y
of systems a n d testing m e t h o d s
lete~mining t h e leakage of enclosures.
c o m e s f r o m a variety of sources, s u c h as the
construction w h e r e leakage paths can be f o r m e d
surface a n d t h e floor slab
~ralt partitions w h e r e gaps in t h e drywall b e h i n d cover
can f o r m leakage p a t h s
Electric switches a n d oudets in drywall partitions that f o r m
,~e p a t h s t h r o u g h t h e partitions
off-normal conditions Qn its resnective s e g m e n t .
(4) Installation of doors with u n d e r c u t s , latching m e c h a n i s m s ,
a n d o t h e r gaps f o r m i n g leakage p a t h s
(5) Interface of drywall partitions at fluted metal deck r e q u i r i n g
seals in t h e flute
(6) Electric outlets in floor slabs within the space or above t h e
space a n d providing leakage to o t h e r floors of t h e building
position) is achieved. T r u e end-to-end verification, therefore.
reouires a c o m p a r i s o n 9f t h e desired oneration to t h e actual e n d
(7) Duct p e n e t r a t i o n s t h r o u g h walls where t h e r e can be leakage
a r o u n d t h e d u c t b e h i n d angles that hold fire d a m p e r s in place
result.
(8) Perimeter i n d u c t i o n systems that often have gaps a r o u n d
ducts t h r o u g h floor slabs t h a t are h i d d e n b e h i n d air distribution
enclosures
An o p e n control circuit, failure o f a fan belt. d i s c o n n e c t i o n of a
shaft coupling, blockage o f an air filter, failure of a motor, or o t h e r
a b n o r m a l condition t h a t could n r e v e n t n r o n e r oneration, is n o t
e~;pected to result in a n off-non;hal indication wi~en t h e controlled
device is n o t activated, since t h e m e a s u r e d result at that time
m a t c h e s t h e e x n e c t e d result. If a condition that nrevents n r o n e r
oneration nersists d u r i n ~ t h e n e x t a t t e m n t e d activation o f t h e devjt;e, an off-normal indication s h o u l d b e disnlaved.
(9) Pipe, conduit, a n d wireway p e n e t r a t i o n s t h r o u g h walls a n d
floors r e q u i r i n g listed t h r o u g h - p e n e t r a t i o n seals
Building. HVAC Systems Suitable for Enclosure Tightness Testing.
Many building HVAC systems can be used to m e a s u r e t h e leakage
t h r o u g h enclosures. T h e s e systems typically contain a central fan
that can draw large quantities of outside air into t h e building for
pressurizing. Because all of t h e s e systems c o n t a i n openings,
ductwork, a n d s o m e t i m e s fans to r e t u r n t h e air f r o m the enclosure
to t h e central air handler, it is i m p o r t a n t that these systems be s h u t
off d u r i n g t h e test. T h e u s e of s m o k e d a m p e r s at t h e points where
t h e ducts leave the enclosure will give m o r e assurance that leakage
f r o m t h e space t h r o u g h this source will be minimized.
Ao4-3 Over the nast t h r e e decades, several network c o m n u t e r
m o d e l s have been written to calculate steady state airflow-and
oressures t h r o u g h o u t a building. At o n e time. ASCOS (See
ASHRAE/SFPE. Desio'n of Smoke Mana~,ement S~stems) was the m o s t
wjd¢ly u s e d m o d e l for ,smoke control ~nalvsis.. a n d it has b e e n
validated against field data f r o m flow e x n e r i m e n t s at an eight-story
tower in C h a m n s Sur Marne. France (Klote a n d Bodart 1985).
(a) Single-Floor VAV Systems. Many m o d e r n office buildings are
provided with a separate air h a n d l e r on each floor of t h e building
to supply c o n d i t i o n e d air to t h e space. T h e s e systems are a r r a n g e d
as variable v o l u m e systems, whereby t h e t h e r m o s t a t s vary t h e
a m o u n t of air delivered to t h e space rather t h a n t h e t e m p e r a t u r e of
that air. This requires a variable f r e q u e n c y controller on the fan
Wray a n d Yuill (1993) ¢valuated several flow algorithms to find the
m o s t a n n r o n r i a t e o n e for analvsis o f s m o k e control systems. T h e
best al~oritlam f r o m this s t u d y b a s e d on c o m n u t a t i o n a l s n e e d a n d
use of c o m o u t e r m e m o r y has b e e n i n c o r n o r a t e d in t h e C O N T A M
607
N F P A 9 2 A - - MAY 2 0 0 0 R O P
that r e s p o n d s to pressure in t h e d u c t system. As the variable
v o l u m e control device is closed, t h e p r e s s u r e builds u p in t h e d u c t
a n d t h e f a n s p e e d is slowed in r e s p o n s e to that pressure. Normally
these systems c o n t a i n air-measuring devices in t h e supply a n d
return ducts that are used to synchronize t h e r e t u r n f a n o p e r a t i o n
with t h e supply fan, so a c o n s t a n t quantity of outside air can be
i n t r o d u c e d into t h e space to m a i n t a i n i n d o o r air quality. T h e s e
airflow m e a s u r i n g devices can be u s e d to m e a s u r e the airflow
i n t r o d u c e d into the space, a n d t h e s p e e d of t h e fan can be adjusted
to control the pressure across the e n c l o s u r e barriers.
(1) Units are located o n t h e p e r i m e t e r with a separate outside
air d u c t for each unit. This typically has a small p e n e t r a t i o n
t h r o u g h t h e outside wall of t h e b u i l d i n g with n o ductwork
attached. T h e a m o u n t of outside air i n t r o d u c e d is so small a n d
t h e capacity of t h e systems to pressurize t h e space is so limited that
t h e systems c a n n o t be used for testing t h e integrity of t h e space. In
these instances, the units will be d e t r i m e n t a l to t h e operation of
any system in t h e space d e s i g n e d to pressurize it unless each
outside air d u c t is fitted with a tight.closing a u t o m a t i c d a m p e r .
(2) Units are located only on t h e p e r i m e t e r a n d outside air is
i n t r o d u c e d t h r o u g h a separate d u c t system. In this instance, the
units are u s e d in c o n j u n c t i o n with a n interior d u c t system. T h e
outside air d u c t for t h e p e r i m e t e r is of limited capacity a n d should
be fitted with tight.closing a u t o m a t i c d a m p e r s to m a i n t a i n t h e
integrity o f t h e enclosure. Testing of t h e space s h o u l d be d o n e
t h r o u g h t h e interior d u c t system.
(b) Centxal Fan VAV Systems. Central fan VAV systems are a
variation of t h e single-floor VAV system. A single fan will supply 10
or m o r e floors, each of which will have a n u m b e r o f variable
volume boxes. As in t h e case of t h e single-floor system, t h e fan will
r e s p o n d to a p r e s s u r e s e n s o r in t h e duct. T h e r e will be a flowm e a s u r i n g station at t h e fan that is used to track the r e t u r n fan with
the supply f a n in o r d e r to m a i n t a i n c o n s t a n t outside air, as in t h e
case o f the single-floor VAV system. Generally, these systems will
also be provided with a m o t o r - o p e r a t e d shut-off d a m p e r at each
floor as t h e system can be economically used to supply only a
portion of t h e floors w h e n o t h e r floors are vacant.
(3) Units are distributed t h r o u g h o u t both the p e r i m e t e r a n d
interior. In this instance, outside air is i n t r o d u c e d into t h e space
t h r o u g h a separate d u c t system that distributes t h r o u g h o u t the
entire floor area. This d u c t system is sized to h a n d l e t h e m i n i m u m
outside air quantities n e e d e d in t h e space a n d m i g h t or m i g h t n o t
have sufficient flow to provide pressure in t h e space. W h e t h e r or
n o t this system can bc..used for t h e pressure testing m u s t be
d e c i d e d on a case ...~..]~e
.t
basis. It will be necessary to provide the
system with a i r - ~ u r i ~ : . s t a d o n s
a n d possibly shut-off d a m p e r s if
t h e system se~...~:."~tipl
.3-.':-~: "-'.~..'.~''.~....
(b) P e r i . ~
I n ~ .~...n Systems. P e r i m e t e r i n d u c t i o n systems
aare
r e typi~
~.~..
t h e p e r i m e t e r of the b u i l d i n g only.
Thes~...~~tems~are arrangg ' ~ . . ~ t h a terminal u n i t a l o n g t h e
pe~ter
tt.'.B.der the w
win
i n q ~ , each of which is provided with a
du~i~a.c~.~,
air distribution
dish
system. T h e d u c t s typically are
s~¥'~'O~:'i
n. ~ (129
(1~. cm ~) p e r unit] a n d either p e n e t r a t e t h e
floor to ~ V ~~bbuut iBoonn system
sy~
on t h e floor below or c o n n e c t to a
vertical r i s d C~fxit:e- ~n dx st e n& u p t h r o u g h t h e building a n d supplies
:o six u ~ e r
floor. "These systems d o n o t l e n d themselves to
• :~0f.s p i e s because of t h e multiple d u c t c o n n e c t i o n s o n each
~i~uct
c o n n e c t i o n s s h o u l d be provided with tight.closing
a a ~ d a m p e r s so pressurization o f t h e space will be possible.
T h e s e systems can be u s e d for testing of spaces by c o m m a n d i n g
that all of the supply d a m p e r s to t h e floors be closed except on t h e
floor being tested. In this m a n n e r , t h e airflow onto t h e floor can
be m e a s u r e d as t h e pressure across t h e barriers is adjusted.
T h e leakage characteristics o f t h e m a i n d u c t system as well as
those of t h e d a m p e r s that are to be s h u t m u s t be k n o w n so the
corrections for d u c t a n d d a m p e r leakage in t h e system of t h e floor
u n d e r test can be d e t e r m i n e d a h e a d o f time. This can be
a c c o m p l i s h e d by s h u t t i n g all t h e d a m p e r s o n t h e system,
pressurizing t h e d u c t system to various pressures u s i n g t h e supply
fans, a n d m e a s u r i n g t h e airflow at t h e air-measuring station in t h e
supply duct.
O n e variation of multifloor VAV system that can be e n c o u n t e r e d
will have air-measuring stations on each floor of t h e building. This
is d o n e to verify that a particular t e n a n t is n o t creating so m u c h
load on t h e floor t h a t m o r e airflow is u s e d t h a n is d e s i g n e d I~t~..->,,
t h e system. W h e n this is e n c o u n t e r e d , t h e airflow can b ~
~ ar'~i
) "~
directly on the floor so that a d j u s t m e n t s for m a i n d u c t 1
unnecessary.
~i::":m":' ~ > : i { i
re is generally a n interior system provided, which is one of t h e
previously described, that can be u s e d for t h e testing a n d
(c) C o n s t a n t V o l u m e Multizone Systems. C o n s ~
volun
m u l t i z o n e systems mix h o t a n d cold air at a c e r ~ ~ (
m~"~'~i~ii~
~
unit a n d h a s a separate d u c t system t h a t goes..~'t to v ~ ~ / ~ pac
Typically, they are n o t provided with a i r - m ~ i n g
s t a t i o ' ~ nat
would have to be retrofitted to t h e ducts d ~ V O ~
air to ff'~ i
spaces. T h e spaces n e e d to coincide with the ~ s u r e s
b~hag
tested. T h e r e is also, typically, no m e a n s of v a r y i ~ . ~ e f i ~ ' t o
each space. Varying t h e flow requires t h e addition ~ i ~ . ~ : r
m a n u a l or m o t o r i z e d d a m p e r s in t h e d u c t system t h a ~ i ~ e adjusted
to achieve t h e test pressure or pressures.
:~"
A-5-$.3.6 T h e test m e t h o d s described in C h a n t e r 5 s h o u l d Drovide
a n a d e o u a t e m e a n s to evaluate t h e smoke-control system's
o e r f o r m a n c e . O t h e r test m e t h o d s have b e e n u s e d historically in
instances where t h e authority h a v i n g i u r i s d i c t i o n requires
additional testing. T h e s e test m e t h o d s have limited value iB
evaluating certain system o e f f o r m a n c e , a n d their validiw as
m e t h o d s o f t e s t i n ¢ a smoke.control system is ouestionable.
Examples o f o t h e r test m e t h o d s that have b e e n u s e d are as follows:
(d) C o n s t a n t V o l u m e T e r m i n a l R e h e a t System. C o n s t a n t v o l u m e
terminal r e h e a t systems are t h e m o s t difficult to use for testing for
enclosure tightness. Typically, these systems contain central fans
that deliver air to a d u c t system at a set t e m p e r a t u r e . T h e d u c t
system is distributed t h r o u g h o u t t h e b u i l d i n g a n d r e h e a t e d coils
are placed at various locations to t e m p e r t h e air to m a i n t a i n space
conditions. T h e r e are typically n o m e a s u r i n g stations or a n y
a u t o m a t i c d a m p e r s in the system. In o r d e r to use this system for
testing, it is first necessary to retrofit it with air-measuring stations
a n d d a m p e r s to coincide with t h e enclosures b e i n g tested.
(1) Chemical s m o k e tests
(2) Tracer gas tests
(3) Real fire tests
A A ~ ~ oz^x , ~ L _ _ : . . , e _ _ , . _ ,r . . . .
Chemical s m o k e tests have
achieved a d e g r e e of popularity o u t o f p r o p o r t i o n to t h e limited
i n f o r m a t i o n t h e y are capable of providing. T h e m o s t c o m m o n
sources of chemical s m o k e are t h e commercially available "smoke
candle" ( s o m e t i m e s called a s m o k e b o m b ) a n d t h e s m o k e
g e n e r a t o r apparatus. In this test, t h e s m o k e candle is usually
placed in a metal c o n t a i n e r a n d ignited. T h e metal c o n t a i n e r is for
protection f r o m h e a t d a m a g e after ignition; it does n o t inhibit
observation of t h e m o v e m e n t o f t h e chemical smoke. Care n e e d s
to be exercised d u r i n g observations, b e c a u s e inhalation o f
chemical s m o k e can cause nausea.
Building HVAC Systems Not Suitable for Enclosure Tightness Testing.
T h e r e are a n u m b e r of HVAC systems that have little or n o value m
testing t h e tightness of a n enclosure b e c a u s e t h e y i n t r o d u c e a
limited a m o u n t o f airflow into t h e space or are a r r a n g e d so that
t h e r e are multiple d u c t e n t r a n c e s into t h e space. T h e r e f o r e ,
m a k i n g airflow m e a s u r e m e n t in s u c h systems is impractical. T h e
s u m m a r y of t h e s e systems is as follows:
This type o f testing is less realistic t h a n real fire testing because
chemical s m o k e is cold a n d lacks t h e buoyancy o f s m o k e f r o m a
f l a m i n g fire. Such buoyancy forces can be sufficiently large to
overpower a smoke-control system t h a t was n o t d e s i g n e d to
withstand t h e m . S m o k e f r o m a sprinklered fire has little buoyancy,
a n d so it m a y be expected that s u c h s m o k e m o v e m e n t is similar to
t h e m o v e m e n t o f u n h e a t e d chemical smoke. This h a s n o t yet b e e n
c o n f w m e d by test data. Chemical s m o k e testing c a n identify
(a) Unitary H e a t P u m p / F a n Coil Systems. Unitary h e a t
m p / f a n coil systems c o m e in a n u m b e r o f configurations.
ese systems are similar in t h e fact that t h e space ts provided with
a n u m b e r o f separate units, each of which has limited airflow
capacity. Outside air to t h e space is i n t r o d u c e d in o n e o f t h e
following t h r e e m a n n e r s :
6O8
NFPA 92A
-
-
MAY 2000 ROP
leakage paths, a n d such tests are simple a n d inexpensive to
perform.
. . . . . . .
T h e question arises as to what i n f o r m a t i o n can be obtained f r o m
a cold chemical s m o k e test. If a smoke-control system does n o t
achieve a h i g h e n o u g h level of pressurization, the pressures d u e to
hot, buoyant s m o k e could overcome that system. T h e ability to
control cold chemical s m o k e provides no assurance of the ability
to control h o t s m o k e in the event of a real fire.
. •. . . .*. . . .~. =
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Chemical s m o k e is also used to evaluate the effectiveness of socalled s m o k e "purging" systems. Even t h o u g h such systems are n o t
smoke-control systems, they are closely related a n d so they are
briefly addressed here. For example, consider a system that has six
air changes per h o u r w h e n in the s m o k e purge m o d e . S o m e
testing officials have mistaken this to m e a n that the air is
completely c h a n g e d every 10 minutes, and so 10 m i n u t e s after the
s m o k e candle is out, all the s m o k e s h o u l d be g o n e f r o m the space.
Of course, this is n o t what happens. In a purging system, the air
entering the space mixes to s o m e extent v~th the air and s m o k e in
the space, ff the purging system is part of the HVAC system, it has
b e e n designed to p r o m o t e a rather complete degree of mixing. If
the concentration of s m o k e is close to u n i f o r m within the space,
t h e n the m e t h o d of analysis for purging presented in Section 2.3 of
ASHRAE/SFPE, Design of Smoke Manatg.ement Systems, is
appropriate. Based o n such perfect m~xing, after 10 minutes, $7
percent of t h e o r i g i n a l s m o k e remains in the space.
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at*~'ib'dtc: r c z u l t ~n tczta t h a t do n e t , n t c r f c r c - ' . " ~ " ~ e h o r n ' .^..2
. . . . . . . . . . . . . . . . . . . .
~
V
.
~
.
.
.
.
.
.
.
.
.
' (a~ For the differential pressure test. the o p e n doors s h o u l d
i n c l u d e tho~e for vdaich the highest pressure - d i f f c r ~ c e was
measured ill the tests with all doors closed (see 5-3.4,flL W h e n
measured with the stairwell as the reference, as described in 58.4.1. thes~ ~loors will have the greatest negative vmlu¢~,
(b~ W h e n systems are designed for o n e n stairwell doors and total
building c w c u a t i o n , the n u m b e r o f o n e n doors s h 0 u l d i n c l u d e the
exterior stairwell door.
. . . . /,. . .-. .:
. - x/
. . ... .. . .
(2 to. ! 9 --s
~.
hc:= ::cd.
(c) Because the oressure in the stairwell m u s t be ~reater than the
vressure in the o c c u v i e d areas, it is n o t necessary t o r e v e a t the
d o o r o p e n i n g force tests with o p e n doors. O n e n i n ~ any d o o r
w o u l d decrease the nressure in t h e stairwell and thereby decrease
the d o o r o n e n i n ~ force o n the r e m a i n i n ~ doors.
for =~l,hrad~r. ~f
~c
g:.: c ~ = : : n . a : a ~ r a ~ h .
C== : h r a m = . t ~ p ~ :
A-5-$.8.1 W h e n testin~ the c o m b i n a t i o n o f z o n e d s m o k e - c o n t r o l
systems and stairwell pressurization systems, the tests aDDlicable to
each stand-alone system s h o u l d be conducted. Differential
pressure t¢¢t~ are specified in both 5-3.4 a n d 5-3.5. W h e n the two
systems are used in c o m b i n a t i o n , the stairwell s h o u l d be treated as
a z o n e in a z o n e d smoke-control system. T h e m i n i m u m d e s k m
pressures snecified in Table 2-2.1 annlv only to the differential
pressure t ¢ ~ specified in 5-$.5.
--
~;,7, ,~2"~. ;.~..T~, ";.~"3. L';~'.'5~7.2y_".~.21 ""~Z.'.2,.~\'2"'=2~Z.'=~_F"~,~ -
.. .. ... .. . -.".. ..I . . ..^.1.. ~. ..: ^.~. . . . . . .
. . m._a . . . . . . . . . . . . .
^£
.1.._
~I -^ ' "~ ~'--"
. . . .
th e
.
.
.
.
.
~^
.
.
I-..
.
.
.
Differential pressure tests c o n d u c t e d as directed in 5-$.4.~ are
used to d e t e r m i n e the doors that should he o n e n e d d u r i n ~ the tests
s o e d f i e d in 5-$.4.4 and 5-8.4.5. It is n o t ext)ected that these values
will c o m n l v with the m i n i m u m d e s i ~ nressures sneeified in Table
2-2.1. except at the fire floor.
.^...~2.2TK :FL2U.23Y2 . . . . . .
6 .
.
.
.
~ u ~
:_:. : ~ = = ,
In lieu o f soecific direction in the local code or contract
d o c u m e n t s , c h o o s e the doors to be o o e n e d as follows in order to
p r o d u c e the m o s t severe conditions:
~ n d SF~ m , x t u r e c a = b.: h e a t e d , h u t c a u t i o n a h c u ! d ~e e x e r t , t e d
k . . . . . . . at h i g h . . . . . . . . . . . . . .
e~= M_ a . . . . . . . . .
:. . . . . . . : .
ce.m..panenm. ? = ::-xh c h e m i c = ! a n . e k e , ~ . . . . . . . . . . . . . . . . . . . . . . . . . . .
609
N F P A 9 2 A - - MAY 2 0 0 0 R O P
B-1.3
(a) For t h e differential pressure test. t h e o p e n d o o r s s h o u l d
include those for which tl~e h i g h e s t pressure -difference was
m e a s u r e d in t h e tests with all doors c l o s e d (see 5-3.4.3L e x c l u d i n g
the d o o r o n t h e fire floor (see A-2-3.7) for rationale. W h e n
m e a s u r e d with t h e stairwell as t h e reference, as described in 5-3.4.1. t h e s e d o o r s will have t h e ~reatest negative values.
Klote• I.H.. A M e t h o d for Calculation of Elevator Evacuation
Time. l o u r n a l of Fire Protection E n g i n e e r i n g . V o l u m e 5. 1993• DD.
83-96.
Klote. I.H.• Design of Smoke Control Svstems for Elevator Fire
Evacuati-on I n c l u d i n g W i n d Effects. 2 nd S~mDosium o n Elevators.
Fire a n d Accessibilltv. Baltimore. ASME. N e w York. 1995 DD. 59-77.
(c) For t h e d o o r - o p e n i n g force test. t h e o o e n doors s h o u l d
include a n v d o o r s (UP to tlTte soecified n u m b e r ) f o u n d in t h e tests
with all d o o r s closed (see 5-3.4,3). to have Dressure in t h e o c c u n i e d
area greater t h a n t h e oressure in t h e stairwell. O n e n i n g these
doors a d d s o r e s s u r e to t h e stairwell, t h e r e b v i n c r e a s i m i door9 p f n i n g forces on t h e r e m a i n i n g doors. W h e n m e a s u r e d with the
stairwell as t h e reference, as described in 5-3.4.1. these doors will
have t h e greatest oositive values. If n o d o o r s m e e t this criteria, it is
[IQt necessary, to r e o e a t t h e d o o r - o o e n i n g force tests with o p e n
d q 0 ~ , since o p e n i n g a n v d o o r would decrease t h e Dressure in t h e
~tairwell a n d t h e r e b y decrease t h e d o o r - o p e n i n g force on t h e
r e m a i n i n g doors.
Klote. I.H.• Alvord. D.M.. E.A,. Levin. B.M. a n d Groner. N.E..
Feasibili-tv a n d Desima Considerations of E m e r g e n c y Evacuation by
Elevators. NISTIR 4-870. National Instute of Sta~nda~ds a n d
Technolo~¢. Gaithersbur~, MD. 1992.
Klote. I.H• a n d Bodart. X.. Validation of Network Models for
Smoke C:ontrol Analysis. ASHRAE Transactions. A m e r i c a n Society
of Heating. Refrigerating a n d Air C o n d i t i o n i n g Ent, lneers. Atlanta.
GA.. V o l u m e 91. P a ~ : ~ 1985. PP. 1134-1145~"
....~
":'%
-Klote• I.H. a z ~ : ~ a u n • E.. Water Leakage of Elevator Doors with
Aoolication ~ i ~ u i i : ~
Fire S u p p r e s s i o n . NISTIR 5925. National
A p p e n d i x B R e f e r e n c e d Pubfications
B-1 T h e following d o c u m e n t s or portions t h e r e o f are r e f e r e n c e d
B-I.1 NFPA P u b l i c a t i o n s .
National Fire Protection Association, 1
Batterymarch Park, P.O. Box 9101, Quincy ' MA 02269-9101.
Publications.
Klote• I.H.• Design of Smoke Control Systems for Areas of Refuge.
ASHP-,AE Transactions. A m e r i c a n Society o f Heating. Refi'igeratir]g
a n d Air C o n d i t i o n i n g Engineers. Atlanta. GA. Vol. 99. p a r t g . 199-3.
PP. 793-807.
(b) W h e n systems are d e s i g n e d for o p e n stairwell d o o r s a n d total
buil~lag gvacuation, t h e n u m b e r of o o e n d o o r s s h o u l d include t h e
exterior stairwell door.
within this r e c o m m e n d e d practice for informational p u r p o s e s only
a n d are t h u s n o t considered part of its r e c o m m e n d a u o n s . T h e
edition indicated here for each reference is t h e c u r r e n t edition as
of t h e date of t h e NFPA issuance of this r e c o m m e n d e d practice.
Additional
|~s-tute ..:~:~-:~&.,
o f : : ~ d s x::-
~ f fx:~..~#~;:~..:~:e c h n o l o ~ v .-- Gaithersburg. MD. 1996•
Klot~!s'l,l-i~ Deal. S.P.. D ~ o g h u e . E.A.• Levin. B.M. a n d Groner.
N.F:.-:~e E~ation
by '~']evat-ors. Elevator World• 1993. DD. 66-75.
I~lot~{~::'~:~Mn. B.1VI. a n d Groner. N.E.. Feasibility of-Fire
E W q U ~ f i ~ w Elevators at FAA Control Towers. NISTIR 5445.
.'~<~v.,.National l t ~ . , ~ f
Standards a n d Technology. Gaithersburg• MD.
"q~
~ . ~. t' M
_
~{-:~
-"
~ .
.::::~
":i.~:.
NFPA 13• Standard for the Installation of Sprinkler Systems. 1999
•
~.:#~}~.~:,
.::::.+.
x<.:.:::'::'6
.~.:}"
:'>.':?-'::
NFPA 80, Standard for Fire Doors and Fire Windows, 199.%~.~ition.}'.:-.-'Y
.~q:~$.':$:::..
.<~: a..'.q<.
" :'-':: ~-.-'.::'::'.~:.~..
~.4 ":~
% J ~ ' ~ - " : " ~ Levin. B.M. a n d Groner. N•E•. E m e r g e n c y Elevator
~'"
"~{'acuatfi~n
2 n d S y- m -p o s i u m o n Elevators• ~ r e a n d
~.:
. . . Systems.
,
~ O ~ s l b l l l t v . Baltimore. ASME. NewYork. 1995 DO. 131-150.
.. "~,:.:,%. -:
.
.
.
.
" ~ .-'::::~
. . . . . . . . . .
ll-t.Z O t l a e r r u o u c a t t o n s
~';'::':':"~{~}}~::..~ , . i } : " - " ~ " ' ~ . , o u g h e e d . G.D.. Mawhinnev. I.R. a n d O'Neill. I. 1994. Full~:.-:!::"
"~.~:
_
~
.
.
.
.
~
, ~
,~
,
'%':'::.::'.%.
"" scale _riFe l e s t s and t h e D e v e l o p m e n t oi Ueslm3 t~nterla ior
B-I 2 1 ASHRAE Publications A m e r i c a n S o c i . ~ ~ n g i ' : : ~ 6 ~ } ~ ........
Sorinkler Protection of Mobile-Shelving Units. Fire TechnoloE¢•
Ref'rigerating, a n d Air C o n d i t i o n i n g Enginee~::]nc., i~~~.~.u]lie":~~'~
V o l u m e 30. D. 98-133.
Circle, N.E., Adanta, GA 30329-2305.
~:-~':"i~}i::..
'%~:
:# .
.
.
.
"."¢"":~L:'}'.'~i::i~:,
:!~..:i~!
Madrzvkowski. D. a n d Vettori. R. 1992. A Sprinkler Fire
ASHRAE/SFPE, Design of Smoke Management ~ ,
1 9 9 ~ i"
Suppression Algorithm. J. o f Fire Prot. Engr] 4: 151-164.
-
"
ASHRAE, Handbook of Fundamentals, 1997.
":~)}~#"i:''r
Walton. G.N•. CONTAM96 User Manual. NISTIR-6056. National
B-1.2.2 ASME Publication. A m e r i c a n Society of M~"-"hanical
Engineers, 345 East 47th Street, NewYork, NY 10017•
Institute of Standards a n d Technoluv• Gaithersburg. MD, 1997,
Wrav. C.P. a n d Yuill. G.K.• An Evaluation o f Algorithm~ for
Analvzing S m o k e Control Systems• ASHRAE Transactions•
Americar~ Society of Hearing. Refrigerating a n d Air C o n d i t i o n i n g
Engineers. Atlanta. GA. V o l u m e 9 9 f P a r t 1~ 1993. on. 160-174. -
ASME/ANSI A17.1, Safety Codefor Elevators and Escalators, 1993.
B-1.2.3 SFPE Publication. Society of Fire Protection Engineers,
7315 Wisconsin Avenue, Suite 1225W, Bethesda, MD 20814.
SFPE Fire Protection Handbook, 1995.
P. !.°-.2 "J.S. C : ' : : ~ - m c r . : P':S]'c=:'c=.
B-1.2.4 U L Publication. Underwriters Laboratories Inc., 333
Pfingsten Road, N o r t h b r o o k , IL 60062.
UL 33, Standard for Heat-Responsive Links for Fire Protection Servic~
1982 (Rev. 1984).
U L 555, Standard for Safety Fire Dampers, 1999.
UL 555S, Standard for Safe0 Leakage Rated Dampers for Use in Smoke
Control Systems, 1999.
610
'J.S. Cc.;'crnm..c:.t P - n ' - n g
NFPA 92B ~
MAY 2000 ROP
Milke,J.&, and Klote, J.H., "Smoke Management in Large Spaces
in Buildings," Building Code Commission, 1998.
Section 2-3.3e: Replace "delta-t" with ~AT."
Table 2-4.1: Replace "Eqn. (9)" with ~Eqn. (3)." Replace "Eqn.
(10)" with "Eqn. (4)." Replace "Eqn. (13-16)" with ~F.qn. (8, 9, 10,
15)" (in all 3lines).
Section 2-4.1.1, 2nd paragraph, 1st line: Replace "indications"
with "indication."
Section 2-4.1.2, 1st paragraph, 9th line and 2nd paragraph, 1st
line: Replace "Equations (7), (8), (9) and (22)" with "Equations
(8), (9), (10) and (15)."
Section 3-2.2.2: In equation (1) "B" should be "n."
Section 3-2.6: Entire section was omitted from ballot.
Section 3-3.1: Move reference to Appendix G, replace "[Schifiliti
and Pucci]" with reference number.
Figure 3-4: Where is it?
Section 3-4.3: In line 5, insert "and" between "present" and "any."
In line 8, insert "a" between "at" and "level."
Section 3-5: In line 3, "fire" should be "fires."
Section 3-6.1: (b) and (c) do not relate to "first indication of
smoke," but to position of smoke layer interface. As such, these 2
sections should be included elsewhere, i.e., in beginning of Section
3-7.
Section 3-8.5.2: Unnumbered equation, presented first, should be
deleted.
Section 3-9: Replace "[CIBSE, 1995]" with reference number.
Section 3-9: Under equation 21, replace upper case "B" with
lower case "13."
In Appendix A, reference numbers need to be inserted where
references are noted, such as in Section 1-4 [Cooper et al 1982],
etc. and references gathered together and appended to list in
Appendix G. See the following sections: A-1-4, A-1-5.4.1, A-1-5.4.2,
A-3-2.2.1, A-3-8.1.2, A-3-9, 13-5.1, B-6.1, B-6.3(a), (b) and (c).
NELSON: 1. Page 92B-16, third line in paragraph following
Figure 2-3.3: Revise (delta-t) to (AT). Lower case t is normally
used to indicate time while upper case T normally represents
temperature.
2. Page 9213-17, Table 2-4.1: In the third column of this table
revise the equation numbers. (9) becomes (3); (10) becomes (4);
and (13-16) becomes (7, 8, 9 and 22).
3. Page 9213-30, Insert following 3-2.5.3: The insert starting with
k~
..~q appears to be a hold over from deleted material and the entire
line'should be deleted.
4. Page 92B-43, extra equation preceding equation (18): There
are two versions of the same equation. Delete the one with 0.0067
as the constant.
RICHARDSON: 1. The terms "natural" and "gravity" ventilator
are both used interchangeable. Suggest correct to "natural"
throughout.
2. Appendix A refers to BR 258. You should be aware that this
will be superseded by a new document from BRE in June 1999, you
may wish to amend the reference.
SCHUMANN: Page 15: Graphs need dries and figure numbers.
Page 38: Add an * to 3-8 ~7.1.2.
Page 42:A-3-7.2.1 (from the 1995 edition) must be revised to
A-3-8.2.1 to match the new text.
Page 58: In A-3-4 there is a reference to Figure A-3.4. There is no
Figure A-~4 in the new text. I do not know what Figure A-3.4
should be.
TURNBULL: The majority of the document has been
substantially improved by this revision. However, I have concerns
that the changes to Paragraphs 4-4.5 and A-4-4.5 have significandy
reduced the integrity of dedicated systems.
The 1996 edition of this document recommended supervision
(now called verification) for all dedicated equipment using
methods that automatically verify proper operation each time the
equipment is activated. The recommended methods did not rely
on manual intervention. Chapter 4 (now Chal~ter 5) contained
additional recommendations for Periodic Testing of dedicated
smoke control systems on a semi-annual basis.
The proposed 2000 edition of this document removed the
distinction between dedicated and non-dedicated equipment in
Paragraph 4-4.5, meaning that this paragraph now applies to all
smoke control equipment. At the same time, a new Item (e)
"Periodic acceptance testing in accordance with Chapter 5," was
added to the list of verification methods in Paragraph A-4-4.5. This
change suggests that equipment should be verified byautomatic
means, such as those described in Items (a) - (d) OR through
semi-annual manual testing. In other words, a non-binding
agreement to test the system twice per year removes the need for
automatic verification. This seems entirely inappropriate, since
system reliability and readiness is a desired factor.
NFPA 92B
(Log #CP1)
92B- 1 - (Entire Document): Accept
SUBMITrER: Technical Committee on Smoke Management
Systems
[ RECOMMENDATION: The Technical Committee on Smoke
I Management Systems proposes a complete revision of the 1996
| edition of NFPA 92B, Guide for Smoke Management Systems in
I Malls, Atria, and Large Areas, as shown in the draft at the end of
I this report.
SUBSTANTIATION: The Technical Committee has conducted a
complete review of this guide and updated it to reflect the best
current information and data related to management of smoke in
large spaces such as atria and malls. A number of changes were
made while significant portions of the text were left as in the
previous edition. Since the entire document is affected by the
changes, however, the Technical Committee believes the entire
document should be open for public comment.
The proposed revisions are designed to reflect the best current
state-of-the-art and the understanding of application that has come
though use of plume dynamic smoke management as covered in
this guide. The principle changes include:
a. Added and updated definitions covering Communicating
Spaces, First Indication of Smoke, Plugholing, Smoke Layer, and
Verification.
b. Additional data o.q the impact of sprinkler operation on
smoke management, including information developed by recent
tests.
c. An extensive discussion of the basic principles and design
methodologies and limitations. This revision addresses important
limitations related to creating and maintaining a smoke layer. It
also addresses the potential and limitations of using gravity vents in
atria, malls or similar facilities.
d. Extensive additional information has been provided on
estimating the heat release of potential fires.
e. Coverage of the response of smoke and heat detectors,
including sprinklers, has been revised to reference NFPA 72,
National Fire Alarm Code, as the prime means of estimating
activation of these devtces.
f. Coverage on system verification.
The Technical Committee wishes to recognize the effort of the
task group that developed the proposed revisions and presented
them to the Committee for consideration and adoption. The
members of that taskgroup include:
Harold E. Nelson, Hughes Associates, Inc.
James A. Milke, University of Maryland
John H. Klote, John H. Klote, Inc.
Gary D. Lougheed, National Research Council of Canada
William Brooks, Eichlea Engineers
Michael Ferriera, Hughes Associates, inc.
Douglas H. Evans, Clark County Building Department, NV
Jvames Quintiere, University of Maryland
ic Dubrowski, Code Consultants, Inc.
Stacy Neidhart, Marriott International
Richard Roby, Combustion Science and Engineering
Doug Carpenter, Combustion Science and Engineering
Win irwin, North An~erican Insulation Manufacturers Assn.
Amy McGarry, Code Consultants, Inc
Gregory R. Miller, Code Consultants, Inc
Michael E. Dillon, Dillon Consulting Engineers, Inc.
Craig Beyler, Hughes Associates, Inc.
COMMITTEE ACTION: Accept.
NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24
VOTE ON COMMITTEE ACTION:
AFFIRMATIVE: 21
NOT RETURNED: 3 Carrafa, Chapman, Pihut
COMMENT ON AFFIRMATIVE:
MILKE: Figure 1-4: Where is it?
Secdon 1-5.7: Replace "Pauls" and "Nelson and MacLennan" with
reference numbers and include these two as references in
Appendix G. References:
Pants, J., "Movement of People," SFPE Handbook of Fire
Protection Engineering, 2nd Edition, NFPA, 1995.
Nelson and MacLenr~an, "Emergency Movement," SFPE
Handbook of Fire Protection Engineering, 2nd Edition, NFPA,
1995.
Section 1-6.3: There's rio change on the last line.
Section 2-3.1: Move reference to Appendix G, replace the
reference in this section with a number for the reference.
Section 2-3.3<1: On page 15, line number 4, replace "1998" with
reference number for:
611
N F P A 9 2 B m MAY 2 0 0 0 R O P
Furthermore, combining the discussions of verification methods
for dedicated and non-dedicated equipment may result in the
recommendations of this document becoming unclear. Many nondedicated components are operated daily for purposes such as
comfort control, and therefore failures of these components are
generally noticed quickly. Equipment operated in this manner
would not normally need the type of verification discussed in
Paragraph A-4-4.5, Items (a) - (d), to provide assurance that the
equipment will operate when activated for smoke control. In
contrast, dedicated equipment and some non-dedicated
components are infrequently or never operated during normal
building conditions. I n these cases, automatic verification
methods, such as those described in Items (a) - (d) would be
appropriate. In both cases, the periodic testing described in
Chapter 5 should be performed.
To remedy the situation described above, I recommend the
following changes t6 the proposed document:
1) Restore the word "dedicated" to Paragraph 4-4.5 so that it
reads:
"4-4.5* Control System Verification and Instrumentation. Every
system should have means of ensuring it will operate if
activated. The means and frequency will vary according to the
complexity and importance of the system."
2) Delete Item (e) in Paragraph A-4-4.5.
VOTE ON COMMITTEE ACTION:
AFFIRMATIVE: 20
NEGATIVE: 1
NOT RETURNED: 3 Carrafa, Chapman, Pihut
EXPLANATION OF NEGATIVE:
MILLER= I agree with the proponent for the reasons stated.
(Log #1)
92B- 4 - (3-5.4): Accept in Principle
SUBMIIq'ER: William Brooks, Eichlea Engineers Inc.
RECOMMENDATION: Replace the existing text with the
followinl~:
3-3.4 (~eilingJet Temperature. Ceiling jet temperature can be
approximated by using the following correlations which depend on
the radial distance from the center of the fire plume.
3-3.4.1 For r / H less than or equal to 0.18:
Ceiling Jet Temperature = Ambient Temperature +
(16.9" ( Q ^ ( 2 / B ) ) ) / H ^ ( 5 / $ )
5-3.4.2 For r / H greater than 0.18:
Ceiling Jet Temperature = Ambient Temperature +
(5.38*(Q/r)^(2/3)))/H
where Q = Total heat release rate
r = radial distance from center of fire plume to selected point
H = vertical distance from fire to selected point
All values in SI units.
SUBSTANTIATION: The present correlation is of little practical
value in design problems, and may not characterize
time/temperature variations from fire test data.
For example, in an atrium 60 feet tall, sprinklers spaced at 15 feet
on center will be at r / H = 0.18. In the same atrium, smoke
detectors spaced at 900 sq ft will be at r / H = 0.35. In both cases
the existing correlation will underpredict actual expected
temperatures due to the 0.6 r / H assumption.
This proposal utilizes the correlations now incorporated into
DETACT for prediction of ceiling j e t temperatures.
The Society of Fire Protection Engineers is conducting a number
of experiments, measuring ceiling jet temperatures. The suggested
correlations can be adjusted during the ROP.
COMMITTEE ACTION: Accept in Principle.
See the Committee Action on Proposal 92B-1 (Log #CP1).
COMMITTEE STATEMENT: Rather than specify the equations
used to determine ceiling j e t temperature for detector actuation,
the user is referred to NFPA 72, National Fire Alarm Code, in the
proposed Section $-3 (see the draft at the end of this report).
NFPA 72, in turn, references use of the DETACT models.
NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24
VOTE ON COMMITTEE ACTION:
AFFIRMATIVE: 21
NOT RETURNED: 3 Carrafa, Chapman, Pihut
(Log #2)
92B- 2 - (1-4 Smoke Layer Interface): Accept in Principle
SUBMITIT_~ William Brooks, Eichlea Engineers Inc.
RECOMMENDATION: Revise the current definition of Smoke
L~oer Interface. Retain all existing text, and add the following:
r the purpose of determining the position of the smoke layer
interface in experiments or CFD simulations, the smoke layer
interface shall be assumed to be height where the temperature has
increased to 20% of the ceiling temperature.
SUBSTANTIATION: The current language defines the smoke
layer interface height in a qualitative manner. This is not
acceptable as we move toward CFD modeling of fire and smoke
behavior. By placing a benchmark in NFPA 92B, experimenters
will have a single definition of smoke layer interface to use in
assessing test data.
COMMITrI~E ACTION: Accept in Principle.
See the Committee Action on Proposal 92B-1 (Log #CP1).
COMMHq'EE STATEMENT: The submitter's proposal, as
expanded by the committee, is incorporated into the proposed
Appendix A-l-4 Smoke Layer Interface (see the draft at the end of
this report).
NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24
VOTE ON COMMITrEE ACTION:
AFFIRMATIVE: 21
NOT RETURNED: 3 Carrafa, Chapman, Pihut
(Log #3)
92B- 5 - (Appendix E, Example 3): Accept
SUBMITrER: William Brooks, Eichlea Engineers Inc.
I RECOMMENDATION: Delete Example Problem $.
SUBSTANTIATION: This example illustrates the weaknesses of
the current methodology. The "apparent inconsistencies" should
alert the committee to the fact that there may be serious errors in
the formulation of the correlations used to develop the "answers."
COMMITTEE ACTION: Accept.
NUMBER OF COMMITrF.E MEMBERS ELIGIBLE TO VOTE: 24
• VOTE ON COMMITrEE ACTION:
AFFIRMATIVE: 21
NOT RETURNED: 3 Carrafa, Chapman, Pihut
(Log #4)
92B- 3 - (1-4 Smoke Layer Interface): Reject
SUBMITTER: William Brooks, Eichlea Engineers Inc.
RECOMMENDATION: Revise the definition of Smoke Layer
Interface as follows:
Delete "which can be several feet thick" from the second sentence.
SUBSTANTIATION: The calculation methods implied by NFPA
92B produce significant differences between the "first indication of
smoke" and the "smoke layer interface." These differences are
more than "several feet," and the present language can lead the
user to feel that the differences are not that substantial.
In fact, these differences can be substantial. For example, using
an atrium size of 100,000 sqft, a fire size of 2000 Btu/sec, and an
atrium height of 100 feet, the calculation methods predict a "first
indication of smoke" at 40 feet and a "smoke layer interface" at 55
feet after approximately 950 seconds.
The term "several feet" does not belong in the definition when its
value depends on a number of variables which could cause it to
exceed "several feet."
COMMITTEE ACTION: Reject.
COMMITTEE STATEMENT: The committee believes the current
definition, as modified in the proposed draft, is adequate. The
language, which is proposed to be deleted, does not hurt the
definition.
NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24
(Log #5)
92B- 6 - (Appendix E, Example 4): Accept
SUBMITrER: William Brooks, Eichlea Engineers Inc.
RECOMMENDATION: Revise this example to be consistent with
previous definitions. In all cases, use the term "smoke layer
interface height" rather than "smoke" or "smoke layer depth...".
SUBSTANTIATION: As the definition and illustration on page
indicate, there is a substantial difference between the appearance of
smoke and the position of the smoke layer interface. If Figure 1-4
approximates real conditions, the use of a design smoke layer
interface height at only 5 to 10 feet above the highest walking surface
612
N F P A 92B - - M A Y 2 0 0 0 R O P
would provide very little safety benefiL By using only the term
"smoke layer interfac& in this example, users would not make the
mistaken assumption that the conditions below the smoke layer
interface height are safe, or that there is no smoke present.
COMMITTEE ACTION: Accept.
NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE: 24
VOTE ON COMMITTEE ACTION:
AFFIRMATIVE: 21
NOT RETURNED: 3 Carrafa, Chapman, Pihut
(4) Contribute to the protection of life and reduction of property
loss.
(5) Aid in post-fire smoke removal.
1-3.2 Specific design objectives can be established in other codes
and standards or by the authority having jurisdiction.
1-4 Def'mitions. For the purposes of this guide the following terms
have the meanings given in this chapter.
Atrium. A large-volume space created by a floor opening or series
of floor openings connecung two or more stories that is covered at
the top of the series of openings and is used for purposes other
than an enclosed stairway; elevator hoistway; escalator opening; or
utility shaft used for plumbing, electrical, air-conditioning, or
communications facilities.
NFPA 92B
Guide for Smoke Management Systems in Malls, Atria, and Large
Areas
Ceiling Jet. Aflow of smoke under the ceiling, extending radially
from the point of fire plume impingement on the ceiling.
Normally, the temperature of the ceiling jet will be greater than the
adjacent smoke layer.
-I-99g 2000 Edition
Chapter 1 General Information
Communicating Space. A g~paces within a building that ~ h a s
an open pathway to.a large-volume space such that smoke from a
fire either in the l ~ u n i c a t i n g space
"
-v
can move
, ""~ "'"
"
" "
~fi~l~'~t4n~
~
Communicating spaces can open directly
~ ~ ' - . ~ s p a c e
or can connect through open
1-1 Objective. The objective of this guide is to provide owners,
designers, code authorities, and fire departments with a method for
managing smoke in large-volume, noncompartmented spaces.
This guide documents the following:
(1)
(2)
(3)
(4)
(5)
(6)
The problem of smoke movement in indoor spaces
Basic physics of smoke movement in indoor spaces
Methods of smoke management
Data and technology
Building equipment and controls
Test and maintenance methods
1-2" Scope. This guide provides methodologies for estimating the
location of smoke within a large-volume space due to a fire either
in the large-volume space or an adjacent space. These
methodologies comprise the technical basis for assisting in the
design, installation, testing, operation, and maintenance of new
~s
and retrofitted smoke management systems installed in bui]
having large-volume spaces for the management of smok...~
the space where the fire exists or between spaces not s~.'~
"~_.
smoke barriers. Buildings within the scope of this g ~
those with atria, covered malls, and similar large-vo[fim~
~r
(See NFPA 92A, Recommended Practice for Smoke-Con..t.r.olSyst
mechanical smoke control between f i r e - c o m p a r t n ~ ~
separated by smoke barriers and NFPA 204-M, (¢~,~ d~,=~,~..A~.
Ventin~ for gravi~ venting.) This guide is~:~..intended::~
warehouses, manufacturing facilities, ov:~'~ifft~!milar s['~,~
guide does not provide methodologies to ass~i~.~.e effeci ~f
smoke exposure on people, property, or missi(~%~.ntin~ y.
activated, such as during smoke control, testing, or manual
9verride qperations. Failure or cessation of such positive
confirmation results in an off-normal indication.
.~.:.....:.
po
'his
First Indication of Smoke.* The boundary between the transition
lone and the smokefree air. as depicted in Figure 1-4. Equations 0
3 and 40 4 are used to predict the height of this boundary, for
smoke fillipg with n0 mechanical exhaust; operating.
The
means, It is. in some circumstances, possible to remove smoke by
gravity venting. The capacity ofgTavity vents to move smoke
through a vent is a function of both the depth and temperature of
the hot layer, Procedures for determining the capabilities of gravity
venting are contained in NFPA 204. Guide_for Smoke and Heat
Venting. That document, rather than this. should be used to the
extetlt that gTavity venting is considered, In general, gravity venting
and mechanical venting should not be used in combination for the
same space without comprehensive modeling of the situation to
erasure that the tyravity vents will not lose efficiency, or even be
reversed by the mechalaical venting.
c
0
•~
layer interlace
1 4 , 15,
ons
121)
UJ
. . . . . . . . dication of smoke
(Equations 9 and 10)
1-3 Purpose.
1-3.1 The purpose of this document is to provide guidance in
implementing smoke management systems to accomplish one or
more of the following:
(1) Maintain a tenable environment in the means of egress from
large-volume building spaces during the time required for
evacuation.
(2) Control and reduce the migration of smoke between the fire
area and adjacent spaces.
(3) Provide conditions within and outside the fire zone that will
assist emergency response personnel in conducting search and
rescue operations and in locating and controling the fire.
Figure 1-4 Smoke layer interface.
Guide. A document that is advisory or informative in nature and
that contains only nonmandatory provisions. A guide may contain
613
NFPA 92B
-
-
MAY 2000 ROP
m a n d a t o r y s t a t e m e n t s s u c h as w h e n a guide can be used, b u t t h e
d o c u m e n t as a whole is n o t suitable for a d o p t i o n into law.
1-5 Design Principles.
1-5.1 Fire in Larg~Volume Spaces, Malls, and Atria.
Large-Volume Space. An u n c o m p a r t m e n t e d space, generally two
or m o r e stories in height, within which s m o k e f r o m a fire either in
the space or in a c o m m u n i c a t i n g space can move a n d a c c u m u l a t e
without restriction. Atria a n d covered malls are e x a m p l e s of largevolume spaces.
1-5.1.1 S m o k e p r o d u c e d f r o m a f i r e in a large, o p e n space is
a s s u m e d to be buoyant, rising in a p l u m e above t h e fire a n d
striking the ceiling or stratifying d u e to t e m p e r a t u r e inversion.
After the s m o k e either strikes t h e ceiling or stratifies, t h e space can
be expected to begin to fill with smoke, with t h e s m o k e layer
interface descending. T h e d e s c e n t rate of t h e s m o k e layer interface
d e p e n d s on t h e rate at which s m o k e is supplied to t h e s m o k e layer
f r o m t h e plume. Such s m o k e filling is r e p r e s e n t e d by a two-zone
m o d e l in which t h e r e is a distinct interface between t h e b o t t o m of
the s m o k e layer a n d the a m b i e n t air. For e n g i n e e r i n g p u r p o s e s ,
the s m o k e supply rate f r o m t h e p l u m e can be e s t i m a t e d t o be t h e
air e n t r a i n m e n t rate into t h e p l u m e below t h e s m o k e layer
interface. Sprinklers can r e d u c e the h e a t release rate a n d t h e air
e n t r a i n m e n t rate into t h e plume.
Pluvholing. T h e condition where air f r o m below the interface is
oulled t h r o u g h a relatively shallow s m o k e la~'er t ~ ¢ 1~o a h i g h
e x h a u s t rate at that noint.
Separated Spaces. Spaces within a building that are isolated f r o m
large-volume spaces by s m o k e barriers t h a t do n o t rely on airflow
to restrict t h e m o v e m e n t of smoke.
S m o k e . T h e a i r b o r n e solid a n d liquid particulates a n d gases
evolved w h e n a material u n d e r g o e s pyrolysis or c o m b u s t i o n ,
t o g e t h e r with t h e quantity o f air that is e n t r a i n e d or otherwise
m i x e d into t h e mass.
1-5.1.2 As a result of the zone m o d e l approach~ t h e m o d e l assumes
u n i f o r m properties (smoke c o n c e n t r a t i o n a n d t e m p e r a t u r e ) f r o m
t h e p o i n t of interface t h r o u g h t h e ceiling a n d horizontally
t h r o u g h o u t t h e entire s m o k e layer.
Smoke Barrier. A c o n t i n u o u s m e m b r a n e , either vertical or
horizontal, s u c h as a wail, floor, or ceiling assembly, t h a t is
d e s i g n e d a n d c o n s t r u c t e d to restrict t h e m o v e m e n t of smoke. A
s m o k e barrier m i g h t or m i g h t n o t have a fire resistance rating.
Such barriers m i g h t have n r o t e c t e d onenin~s. SmS!zC bz~--c~ cma
1-5.1.3 A n equilibrium position for t h e s m o k e layer interface can
be achieved by exh.~usting the s a m e rate of s m o k e as is supplied to
the s m
o k e llaye
:note
a y e r . . . . ~ : . . s m o k e e x h a u s t can delay t h e rate of d e s c e n t
of t h e s m o k e 1~
1-5.1.4
adjacenl
atr iu m~i
Smoke Damper. A device t h a t m e e t s t h e r e a u i r e m e n t s of U L 555S,
Standard for Sakt~ Leakage Rated Darnt~ers for Use in Srtlok,¢ Control
S~stems. ciesi~n-ecl to resist t h e nassa~e of-air or smoke. A
c o m b i n a t i o n f i r e a n d s m o k e d a r n n e r s h o u l d m e e t t h e requirement,~
of U L 555. Standard for Safet~ Fire DaraOers. a n d U L 555S,
I
^.1
. . . .
A^.:~--~A
~ A
E I . ~ A
+. . . .
.--~1.--
T~t . . . . . .
:.~
A . . . . .
47'^_
TT.~
+1~ . . . . . . . . .
:. . . .
+1~-.
:~
~--^1.^
g" ~ : . . . . . .
---^--
/~^--+.^1
I,^
~1~ . . . . . .
¢~._+ . . . . .
A
A
+.
:.
g'~..^
.~--I..:---~:^--
:. . . . .
supplie~.
rate of a
~.f'TTT
:l.~?l~..-'~
o r d e r for t h e s m o k e e x h a u s t fans to be effective, m a k e u p
~ r mff.~ be provided. M a k e u p air s h o u l d be p r o v i d e d at a low
velod{y. For effective s m o k e m a n a g e m e n t , the m a k e u p airflow
'st be sufficiently diffused so as n o t to affect t h e flame, s m o k e
Jme, or s m o k e interface. T h e supply points for t h e m a k e u p air
s h o u l d be located b e n e a t h t h e s m o k e interface. T h e rate of
m a k e u p airflow s h o u l d n o t exceed t h e e x h a u s t rate s u c h t h a t t h e
a t r i u m or mall achieves a positive pressure relative to adjacent
spaces. If air enters t h e s m o k e layer above t h e interface, it m u s t be
a c c o u n t e d for in t h e e x h a u s t calculations.
KKK
S m o k e Layer. T h e a c c u m u l a t e d thickness of smokd;.:~;t
physical or t h e r m a l barrier. T h e s m o k e laver is n o t ~ "
smokefree
air.
"::'~!i!''~:'"
i:~ii~.:~'~!~'~
Smoke Layer Interface. The theoretical b o u n d a i ~ e e n
.tt"-~x.'~oke layer has d e s c e n d e d to t h e level of
ied~es,
p r e v e n t i o n of s m o k e m i g r a t i o n f r o m t h e
Lo t h ~ . ~ i ~ q ~ a t spaces c a n h e a c c o m p l i s h e d by
; or o p ~
airflow. NFPA 92A, Recommended
,e-contra~..#~Systems, provides g u i d a n c e o n t h e use of
s m o k e migration. O p p o s e d airflow can be used to
aigradon into o p e n adjacent spaces, with air
rithin t h e adjacent space. T h e r e q u i r e d volumetric
]ed to achieve t h e necessary velocity can be
1-5.2 Fires in Communicating Spaces. Fires in c o m m u n i c a t i n g
.~Phaces can p r o d u c e b u o y a n t gases that spill into t h e large space.
e design for this case is a n a l o g o u s to t h e design for a fire in t h e
large space. However, t h e design m u s t consider t h e difference in
e n t r a i n m e n t behavior between a free p l u m e a n d a spill p l u m e . If
c o m m u n i c a t i n g o p e n spaces are p r o t e c t e d by a u t o m a t i c sprinklers,
t h e calculations set forth in this guide m i g h t s h o w that no
additional venting is required. Alternatively, w h e t h e r
c o m m u n i c a t i n g spaces are sprinklered or not, s m o k e can be
p r e v e n t e d f r o m spilling into the large space if t h e c o m m u n i c a t i n g
space is e x h a u s t e d at a rate to cause a sufficient inflow velocity
across t h e interface to t h e large space.
a
s m o k e layer a n d s m o k e f r e e air, as depicted in F i g u l ~ 1 4 . In
practice, t h e s m o k e layer interface is a n effective b / ~ n d a r y within a
transition buffer zone, which can be several feet thick. Below this
effective boundary, t h e s m o k e density in t h e transition zone
decreases to zero._This h e i g h t is u s e d in t h e application of
Eouations 8. 9. 10. a n d 15.
S m o k e M a n a g e m e n t System. An e n g i n e e r e d system that includes
all m e t h o d s that can be u s e d singly or in c o m b i n a t i o n to modify
smoke movement.
1-5.3 Detection. Effective design of s m o k e m a n a g e m e n t systems
requires early detection of t h e s m o k e condition.
Stack Effect. T h e vertical airflow within buildings caused by the
t e m p e r a t u r e - c r e a t e d density differences between t h e building
interior a n d exterior or between two interior spaces.
1-5.4 Fire Suppression Systems.
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
t" . . . . . . . . . . ] . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
b ..................
l ~
1-5.4.~L~ A u t o m a t i c suppression systems are d e s i g n e d to limit the
mass b u r n i n g rate of a f i r e - s ~ a n d will, therefore, limit s m o k e
generation. By limitin~ t h e mass b u r n i n ~ rate o f a fire. s m o l ~
~eneration will be reduced. Fires in s p r i n k l e r f d spaces adjacent to
atria a n d covered mall pedestrian areas can also be effectively
limited to cauzc .--'nimal r e d u c e t h e effect on a t r i u m spaces or
covered mall pedestrian areas a n d thus increase t h e viability of a
s m o k e manageme(l~ system.
T e n a b l e Environment. An e n v i r o n m e n t in which s m o k e a n d h e a t
are limited or otherwise restricted to m a i n t a i n t h e impact on
occupants to a level that is n o t life threatening.
Transition Zone.* The laver between the s m o k e laver interface
a n d the first indication of s m o k e in which t h e s m o k e laver
t e m n e r a t u r e decreases to a m b i e n t .
614
N F P A 92B
-
-
MAY 2000 R O P
1-5.4.82" Ac'-;~dea o f :~.~.:k!er: ne:r : fire ~."l! ~."~u=e ccvliag of
rc~ulfing in a lo~: of buo)~'~c)'. The likelihood of
sprinkler activation is d e p e n d e n t on--the on many factors includin~
heat release rate of the fire and the ceiling height. Thus, for
reddest fire sizes, sprinkler operation is most likely to occur in a
reasonable time in spaces with lower ceiling heights, such as B ft
(2.4 m) to 25 ft (7.6 m). Activation of sprinklers near a fire will
cause smoke to cool. result~n~ in reduced buoyancy. This reduced
buoyancy can cause smoke to d e s c e n d and visibility to be reduced.
The equations in Chapter .B that illustrate smoke filling [ ( ~ ) and
(~-~)] and production [(4-¢8), ( 4 ~ . ) , (4-7_J_0.), and (-24-_1,5.)] do
not apply where a loss o~ buoyancy due to sprinkler operation has
occurred.
effect must be considered in selection of exhaust fans. The effect
of temperature and wind velocity varies with building height,
configuration, leakage, and openings in wall and floor
construction.
" ~. . ....... . . . . " ^,
1-6.4 Pressure Differences. T h e m a x i m u m a n d m i n i m u m
allowable pressure differences across the boundaries of smoke
control zones should be considered (see NFPA 92A, Recommended
Practice for Smoke-Control Systems). T h e m a x i m u m door opening
forces should not exceed the requirements o f NFPA 101% Life
Safety Code ®, or local codes a n d regulations. T h e m i n i m u m
pressure difference should be such that there will be no significant
smoke leakage during building evacuation. The performance of
the system is affected by the forces of wind, stack effect, a n d
buoyancy of h o t smoke at the time of fire.
1-5.4.3" Snrinkler activation in spaces adiacent to an atrium will
result in coolin~ of the smoke. For low heat release rate fires, the
temperature of the smoke ]eavin~ the c o m n a r t m e n t is near
ambient, and the smoke will be dispersed over the heiffht of the
opening. For hiffher heat release rate fires, the smoke temperature
will be above a m b i e n t a n d t h e smoke enterin~ the atrium is
1-6.5 The design objectives contained in Chapter 1 can be met by a
variet~ of methodologies. Some of those m e t h o d s are further
explained in Chapter 2.
Chapter 2 Design Considerations
o__~o~_~.
bu
1-5.5 Operating Conditions. T h e smoke m a n a g e m e n t system
c o m p o n e n t s should be capable of continuous use at the m a x i m u m
temperatures expected, nsing the calculations contained in this
guide.
1-5.6 Tenability Analysis. Where the design is based on
maintaining tenability of a portion of space, one of two approaches
can be pursued. First, the design might d e p e n d on preventing the
d e v e l o p m e n t of a smoke layer in that portion o f the space. Second,
the design might be based on comparing the qualities of a smoke
layer to hazard threshold values. Such a demonstration requires
that the effects of smoke on people be evaluated. Tenability factors
that can be considered include, but are n o t limited to. the
followina:
(a) Heat exnosure
(b) Smoke toxicity
(c) ~
~<"~:::':*':~"~"'~a~ili
i
Tenability analvsis s u c h aa c--M'aut':on is outside t h ~ e
oL~is,,
guide. However, other references are available that '~re:~:,.:...::.:"~
analytical m e t h o d s for tenability analyses [34]. ~
"''~:'*-~'?:-2~:..
.....
(a,\
to
Ti~
E':.^
.....
:
. . . . . .
I . . . . . . . . .
n I..~ ..........
: . . . . . . . . .
r .....................
C . ~ 1 . ^
2. Rc.'r..::'c : m e E t from k".e !=gc vc!ume space a: a rctc :'Jffic'cn:
1.
V'
1-6 Design Parameters.
n
I. . . . . . . . . . . . . .
*h~
1-6.1 General. Design criteria should include an understanding
with the authority having jurisdiction of the expected performance
of the system and the acceptance test procedures.
2. Prc:'cnt ;mokc from er.tcNr.g Xk.c !m-gc, -vv
........v~
.~.t '.t ". . . .
. . .
~)'
"~ ~ r f l c-'.'.
2 !.2.2 ~.~=:=F,c=c:t c f S-----e!:c -- Ce==:=='==d=g Space.
1-6.2 Leakage Area. Design criteria and acceptance testing of
smoke m a n a g e m e n t systems should be based on the following
considerations with reference to the smoke zone and
communicating zones:
~
Fire c - - - a a t c = "n l=:'~e ":c!'-mc :-=co.
_¢'...':T::'=2":.Td.*.':FZ:22"2Y':2Z~:o':,::':~ZT;2: 2Z 2;;'." ~...:2 2 " e - "
(1) Small openings in smoke barriers, such as construction
joints, cracks, closed d o o r gaps, and similar clearances, should he
addressed in terms of maintaining an adequate pressure difference
across the smoke barrier, with the positive pressure outside of the
smoke zone (see NFPA 92A, Recommended Practice for Smoke-Control
2=:2:oo~,: Z "~.Y:..~.v:L'::'.T::F'-7~Z::L~'L=:" ~r~7:22?.2 ..:::~-2~:~.
n o t b e c o , ~ , ~ ! c t e ! 7 c f f c c d ' : c "Z ~h.c go'-:rce o f ~-.e .~;c :.3 ~ : c c d 7
............................
S y a ~ s ).
I. . . . . . .
(2) Large openings in smoke barriers, such as open doors and
other sizable openings, can be addressed in terms of maintaining
an adequate air velocity through the openings) with the airflow
direction into the zone of fire origin.
~, : p : c c : :v. xh.e ".=FFer pottle= of t.he
I. . . . . . . . .
2. E:'~au:t the !argc vc!ume :pace co that
1-6.3" Weather Data. The temperature differences between the
exterior and interior of the building cause stack effect and
d e t e r m i n e the stack effect's direction and magnitude. The stack
it i:
at a n c ~ d : ' e
g. U:c ~-::2.ow ^~ "~::c"..=:ed in tD.~: a c e ' - m o r n or h a r : ' . e : ~z
d i s c u = e d in N ~ A 9 ~ s. or bo+~.
615
NFPA 92B -- MAY 2000 ROP
2 A ~ = e :.= ++he w...=rg= Ve!'.=---= SF+-.=e.
. . . . . . . .
~C
+
. - - ^ I
.:.I-,:~
. . . .
+I*.: . . . . . .
:^
.3: .......
.4
~.T~'OA
:~
I+XOA
O
A
1
. . . . . . . . . . .
~'--^I
..--~---.
+
c^-
1. . . . . . .
I. . . . . . . . . . . . .
!ar-e~, -'al'-mc s-=cc~, cr tc !ir:-:t "&c m..c'.:nt cf smc!:e f r a m
the use cf phTsic=2 ~ a r - c r s ta limit =mckc mc-'emcnt cr methadc
*-w limit smoke v~'~a"-':^-, such az c=ntrcll!ng t.hc fucl ~.r us!rig
autom=tiz fire suppre==!cn.
.~v^_+.1:.
2 !.$ gad= Caaddc~-t':caa. The =c:cc+~an af :'=r'ca= 4csign
. . . .
~-^ . . . . . . .
:.-3--
•" P 1 - _
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m a n a g e m e n t s):tcm ":s pra-a.dcd t= ms!st s~fc c;'acaa*dcn, ace=par::
rcac'dcn ~ m c tc "..he c m c r g c n c 7 a n d e-ac-.:a4cn "4me =hc'a!d hc
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c o m m u n i c a ~ e g space.
(d) A=caz cf refuge, cP..hcr tcmpara=3' c r indefinite.
q
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2 2.1 Smoke Aae=m:!ar:a= D~pt~. It !a n c t a =ea!!='dz.72!7
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1. . . . . . .
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..^I
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A'-t~ma+2c a-.etec~en de:'ce= :h='-'!d n e t ~e :~nnecte~ a~rec+J}' te
the :mo!-c m a n a g e m e n t :}:tern " ; ' ~ c : : : f a r ' h e r caneern for ~ e
--A
. . . . . . .
+'. . . . . . .
.4
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~+I~
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+---.X
.....
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i~kh *..heir pe~er.'r~nce Luring n e r m a ! . . . . . . : . . . . .
as+:. . . . .
affected 57 en'Aronmcnt=2 factors, aver "&e life of the a;.=tc..'q, - ~ d
• c~r ab!!K~/ta ;.~h=tand ~hc s~csscs e n d u r e d d a ~ n g a fire.
Typi~ll7, s'.:cE a c c m p e n e n t r e : ' e w "s cenducted in *2".e e':a!ua*don
.....
~ "
ml A
~
+++It
~
+ ~
+ u ~ c ! e n t e n o u g h to ensure re!.:abi!!t7 of the c e m p o n e n ~ . ?Ass, the
impact cf xhc func4anal d e p e n d e n c e cf "..he ce.mponcn~= an one
. . . . . . .
+
'I~ . . . .
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-4
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2 ~.2 Pc='c~'c Taa:':=.g. P c - a d i c te=+dng is c+~aen*a~ ta cnaurc that
t.t,.
:~
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mechanical ¢. . . . .
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c ~. ... .. v. ... ... .. . . . +I++ A +. +. +. .~.I + .:. +.+.- -.+. . . . . ..+. l. t.~. k. t. l. ~. ..- .- .. -. +I-. , . .; . . . . :.. . .. .. .. . . .A .+ A. . . A I + o,
f r c q u z n t ma!ntenm-:cc =rid tes'dng ==c n c c d c d tc =.==c= the =}~tzm
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r
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r
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A:f-~.....l+
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par'dall 7 prc;~dcd as . . . . . u, . . . . .
...I+_ . . . . . . .
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h+
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~Eh.'.L~d^72EL"~2"~ ".:[[2"..'~Z::'I- yT..~2,;['TL'2Z:7.,~'.'"2:r..2~2~
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g.'d7-Z?2::.2Z +^T,-,X~.2Z.2 aZ~.\E2,'J',..'2"~7.~g 7.'..'-Z'~,J2L-=~g'Z2T
:I,~I~
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616
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I" . . . . . . . . . . . . . . . . . . . . . .
! . . . . . . . . . .
1
NFPA 92B -- MAY 2000 ROP
.l~|al~l
0
A
~
]kA" . . . . .
I
A
A^+.'=--+.~----
C
. . . . . .
. . . . . .
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. . . .
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The !~.~'-"cn~f +-he er~=.".==t~__:-chz=getc +-he ~u~:.a-e:h-~'-'!d~e
. . . . . . . . . .
(a) ~". . . . . . . . . . . .
+--^I,~
~I
. . . . . . .
k
+^A
.'--+ . . . . .
+^
~II
+
.:A^.
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+I++. . . . . . .
(a/ The height, cross-sectional area. and plan area of the large
volume to be protected. Height and area ~re kev elements in the
determination of smoke accumulation, descent, and control.
(bl Tvoe and location of OCCUPancies within and
communicatin~ with the large-volume space. T h e height, size. and
arrangement of onenin~s between the occupancy within the
communicatin~ soace and the large-volume soace are important
considerations.
2£'~'3933 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . .
O
A
~
b""
I~__.__+.'_.~.
J~ . . . . . .
......
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A.
.'__+:__
~ . . . . .
I) ......
+1 .
.
.
.
.
I.^
7~Z-,T2=;~Z,\',~3~.ZZL\-;.;U22:L."2R2"'-';;~
"_..2",2Lk~'772"..~
.1-. . . . . . . .
^--,--:
.,,-I
. . . .
+ ..^I^.:~.
g:..^
^ C -
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-1 Basic Considerations. T h e selection of various design
objectives and methods d e p e n d s on the vrotection ~oals, such as
pl-9~ecting egress paths, maintaining areas of refu~effacilitatin~ fire
deoartment access, or orotectin~ Drooertv. Consideration nee~ls to
be ~iven to the following:
qua.n:ity "= d c t c r m ~ a c d . . . . . . . . . . . . . . . . . . . . . .
. . . . . . .
!
.......
~I,,~^
: 22~72217,---FJ7.1%~\~ : ~ Ffi: 7:22-~" "e2~~ Z: :l ~';'~ E_'"'"Y'~
c a ! c u l a ~ . n . ~ . : ~ : ~ f:= xhc m'=':=:u=n ~ : : --:tczity.
2~..~ For z A j a c e n t =p=v.~ ~¢!=:-" t-he : m = k e !:}'=r "n'.e~ace, ~--n7
1-. . . . . . . .
.^.,1
.^
I*.^
I.*--*..^A
2 g N r : ': S ~ : : =
:--
I-.^-^1
S-~:-:~-::g
,~.,,-, ~ \ ~ - Z : T 2 : j v T . ~ 2
•
-..,^--.
^--I
~..~:Vo!---:
.^_.__:__+f.^_
EF:::.
-. . .~. .
j . . . . . . . . . . . . . . . .
j ......
to reach an exit or area of refu~e.
(21 Maintainin~ the s m o k e laver interface to a t)redetermined
r
2 ~.~ ~ - c ": C c , - - m - : ' c a t ' a g S F a c c a
(31 Allowinlt fire deoartment t)ersonnel to atmroach, locate, and
extintmish a i~e.
-(41 -Limitln~ the rise of the smoke laver temt)erature and toxic
~as concentration, and reduction of visibilltv.
2-3 Deshm Limitations.
O
~
O
10
"Pt.
. . . .
K ....
+ --..*^
~-.^--
.1._
I. . . . . . .
:.2;:'2":~72: ~2k-~'TZT,,3::'_.'_'".L-_~
I. . . . . . . . . . . .
A.
*^
2-3.1 S m o k e Accumulation Devth. T h e rate o f s m o k e laver
~ ~ l u m e
s p a c e i s ojaly weaklyrelated.l~ t h ~ $
o f t h g . ~ a c e and l~e rate of heat release o f the fire. S m o k . ¢ , . l ~
descenK_however, is stroogly rela~ed to the c r o s s - s e c t i o n ~ . a £ g , a . ~
th~ll~me
space i n ~ l v e d . For these reasons, careful
calculations using the equatioas and m e t h o d o l o ~
this
d o c u m ent are necessary_ in any situation w h e r e the i a ~ n f i o n is to.
p3.2vide s m o k e m a n a g e m e n t througt:Lfl3e use o f a n u n e x h a n s ~ d _
volume such as a s m o k e coilectiou.K~ace.
k^
2~'"_"_'~, : g 2 ~ ' : 2:72~..Z"_ - ~
: { 2 7 . Z ' 3 2 2 ~ : 3 . Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . .
7.
cc~'n~= ~ f u p p : r ~ e ~
. . . .
:KIII~,
tK--t
. . . . . . . . . .
tK."
•: .
.
.
.
e.-2:m =_rid :h:'.:'! ~- ~ : : c = : ' ~ : r : ~ .
. . . .
.
.
.
I ....
.
.
.
~11
A
^--+
.1~-
. . . . . . . .
I~ . . . .
A
Th.ere is a
fl . . . .
+~:
. . . .
I.^
--:--L.+
^.
--:--I~.
The m i n i m u m d.ed~thof the s m o k e layer is determined by_~oth the
lhic~s
(drd~th)__Qf,_~e c e i l i n g i e t a s the rising_plume rams as it
reaches the too of the s v a c e and the d~d~thnecessarvto Dreven$
p_lugJao l ~ g . For thes e reasons, nod_esigu s h o u l d b e b a s e d o n
~ g
a s m o k e laver at a pQint higher than the level of,.fl3e
ceilingi et Or the pgi nt of eli m i n a t i o u o ~ g l ~ l i n g ~ _ ~ i c h e v e r
is
lower.
;:7'Z=22~'2"~Y%Z;2L" 2., ~ ' 7 . ~ -L ;5- ~-2"L2;: f ; i h~. . . . . . ~ . . . . . . . . . ~ " "
" _ : ' : ~ o ~ " ZF :.~ ~.77":~,. U~Z\~. ~.'~L .,-~.: Z ~ "L'f ~ _ " ~
. . . . . .
+I~^
C.
. . . . . . .
C+I~
. . . . . . . .
+^
-01.:
t~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
--
....
--'--
. . . . . . . . . . . . .
"I . . . . .
/
. . . . . . .
....
.1-'..
^--J
t~l~__.^_
~2
o
The thickness o ~ e ceiling jet has been_r._e,~rted [B.e~.e~
C.(1986). Fire Plumes and__CeilingJem. Fire SafetyJ o u m i ~ . l J . ~ l ~ _
63-651 as in_t~e range of 10% to 20% 9f th.~_distance from the
sou rce f ~ e ~ th e tOl~Of__~b~_laace.
~ ................
l
. . . . . . . . . . . . . . . . . .
617
NFPA 92B -- MAY 2000 ROP
P l u g b o l i n g _ i L ~ e c o n d i t i o n w b e r e air f r o m below the i n m ~ a c e is
g g g e d throLivh a relatively s hal low_ s m o k e laver due to a h i ~ _
e x h a u s t rate atthi~£Doint. T h e i m p a c t o f _ D l u g J ~ l i ~
be
m a n a g e d (see Section 3-91,
E
1
0•9
•i
0.8
0.7
g o.6
$-3.2 Disruntion o f S m o k e Laver I n t e r f a c e . Any factor that causes
in~rbulence
inor i n ~ w _ i o t o
the s m o k e
laver o r a t t h e interface c a n affegU;be s m o k e laver. Amol~g3j3ese
factors are t h e following~
0.5
"~ 0.4
0.3
0
(a) O p e r a t i o n o f a u t o m a t i c sprinklers above the s m o k e laver
interface can draw the s m o k e belo~' the s m o k e laver interface.
.(.~) Stron~ air currents from I-[V~(~ systems o r el ements o f t h e
stooge m a n a g e m e n t s vstem dis c h a r g e d n e a r the s m o k e laver
interface can disrut~t th.c.Loterface so as to cause s m o k e to descend_
belo_wd~e s m o k e laver interface.
(c) A ~ c u r r e n t s at over 200 f t / r a i n (61 m / m in)_ s _ . L r . U ~ g _ ~
gl~.me below the interface c a n c a u s e the_l~lume m b e n d ann_
~ c r e a s ¢ the rate o~¢_0trainment air. cau~_iDg s m o k e to d e s c e n d
belo_w_khe level calculated b z.th.e_.c_qua6om in this d o c u m e n t . T h e
I o c a t i o t a o f the fuel load. a n d the ootential p l u m e ~ o m s u c h fuel
load. th.c.,olacement o f su~Rly_Doints, a n d the vein city at the s up/~lv
p_.flints in relation to the,QJ~me Iocadoo_.0eeds to be analyzed,_
(dL_U_.oward thrus ring airflows locatedbelo_w the interface having
LUfficient m o m e n t u m to reach t h e layer c a n cause b o t h mrbi!lent
mi~ng_t~ disruRt the i n , t r a c e a n d a d d m a s s to the s m o k e I aver to.
c a u s e t h e layer to d e s c e n d b.~gw ~ e laver interface.
(e) Air forced._Qr in[Juced into t h e ul212er layer by m e a n s o t h e r
than t h ~ . l ~ m e will increase the mass in the u ~ e r laver c a u s i n g
th a_~J.~L~_~.d e s c e n d b e l ow thg,._desi ~ de_othunless COilll~ens ated_
for i n t h e s m o k e m a n a g e m e n t s ~ t e m d e s i ~ x
=(/)
0.2
o.I
~:
,
0
0
,
.
i
. . . .
[
i
'
'
l
. . . .
i
300
400
rise (°F)
Temperature
Figure 2-3.3(a)
I
200
1 O0
M a s s f l o w e f f i c i e n c y t h r o u g h a vent.
A l t h o u g h Figure 2-3.3(a) indicates a n aonreciable reduction in
the effic[encv of a natural vent with small-fires Droducinu a m o d e s t
increase in s m o k e laver temperature• a small fire also Droduces less
smok~, thereby reouirin~ less venting. Mjlke a n d Klote e v a l u a t ~
the effect of d i f f e r ~ : : h e a t OUtPUtS of fires on t h e vent area that is
n e e d e d to m a i r k ~ " ~ " ~ k r t i c u l a r clear h e i g h t [1998]. This analysis
indicates t h a ~ t z o u i r e d
vent area is re(afivelv insensitive to the
heat outnu~f th~i~e.
.::::... '::~i~.,
"::':@~ii-:~
....
F i ~ u d i ~ ! ~ ! i ~ ) d e n ~ i r e d vent areas to m a i n t a i n various
s m ~ interface laver h ~ t s
for uiven fire sizes a n d ceilinu heights
~ ¢
~ v s i s by M i ~ e a n d IZ~gf;¢,
":~:i:.::>....i:i:: ~
-.x~
The
canabilitv
of b u o v- a n t forces to move s m o k e t h r o u g_ h a natural vf~t ~.-.::..<...
70 -:%i%::::~-::i::
• ..
......-.::~ ~ .:.;.:.:~.
is a f u n c u o n of both t h e deDth a n d t e m n e r a t u r e of t h e h o t lavgL
'-.:~U:::.-':.:~'.:.:i~.:"~i
iili::::!'::"
T h e ~ravitv-induced m a s s flow t h r o u g h vents increases with "
'~iii!.. '"::: %'-::~'~""?:':....
increasin~ d e p t h a n d increasin~ t e m n e r a t u r e . T h e methodolo~,v
% ..~!
for assessin~r t h e mass flow t h r o u g h a vent is c o n t a i n e d i n _ . . ~ .
::~"
~04, Guide for Smoke and Heat Ve~tin~,
...#;.... -i~iili
"%:,
_
_
::..~..-,.-.~,~.
..p'..
... '~:-.'~
2-3.3 S n e c i a l C o n s i d e r a t i o n s R e l a t e d to N a t u r a l V e n t i n g .
N o ~ a _ a l l z ~ a t u r M a n d mechaui~;al v e n t i n g a r e i n ~ ~ ' : "
each o t h e r if thev serve t~¢ s a ~ ¢ air v o l u m e . Thex.e.is a ~ i ~ c a n t
.......
p_Q~glial f o r a s h o r t clrcuit o f the airflow w h ~ ~ , . . , : ; ; :
are reversed in flow directiol] 1;9 b e c o m e t t ~ % u r ~ ~ ~ i
"~'"
m e c h a n i c a l vents. A n L d e s i t , n that c o n s ~ : = u c h
a m ~ ve6~..~g
m e t h o d s needs careful engil~eering.AIlat~sis"'~..:'.':':':~.h,ysical ( ~ l e )
m o d e l l m to e n s u r e t h a t th.e desit,rl will f u n c d ~ ! ~ i n t e .r~f~d.
/
l
4o
3o
0
0
----3orn, S M W
~ ~ " t ' ~ " ~ '
6
Figure 2-3.3(b)
/
/"
/
,
12
Clear
Potenfi al envirolamental wind co n ~ fi o n ~ ~
nsideratioiL
o f the i m p a c t ofanx_gearb,Ll~ortions o f the b _ u ~ d j ~ , _ . q ~
s t r u c m r e s . ~ a t can cause d2_wn d ~
to_.Lbee v a l u a ~ d in a n x
d e s i ~ d e p e n d e n t o n n a t ~ a l vents.
15 m 2.5 MW
15 m 5 M W
- - - 30 m, 2.5 MW
~
height
,
~
18
,
.
.
~
24
.
.
~
I
30
(m)
V e n t a r e a r e q u i r e d to m a i n t a i n c l e a r height.
T h e effectiveness o f natural vents can be appreciably r e d u c e d or
eliminated w h e r e t h e o u t d o o r air t e m n e r a t u r e is high. O n e
scenario of narticular c o n c e r n involves a fire occurrin~ in a spBce
with an i n d o o r t e m p e r a t u r e that is less t h a n t h e o u t d o o r
t e m p e r a t u r e (i.e.. s u m m e r conditions with a n air-conditioned
atrium). While t h e s m o k e m a y be b u o y a n t relative to the i n d o o r
air a n d rise to t h e ceiling, once t h e vent onens• o u t d o o r air will
e n t e r t h e buildin~ if t h e o u t d o o r air t e m n e r a t u r e is ~reater t h a n
that of t h e s m o k e laver. As such. n o s m o k e will be e x h a u s t e d a n d
t h e s m o k e laver interface can d e s c e n d .
T h e mass of s m o k e is onlv weakly related to t h e rate of h e a t
felt'rise of the fire whereas t h e s m o k e laver temDerature nearly
varies directlv with t h e rate of h e a t release. Conseouentlv. a fire
that is s i ~ i f i c a n t l v smaller t h a n t h e design fire wilf onlv n r o d u c e a
low t e m p e r a t u r e s m o k e laver, with less mass flow t h a n flaat of t h e
design fire. However. less flow is necessary to provide ventin~ for
the smaller fire. Fi~,ure 2-$.$(a) is an evaluation of t h e efficiency of
mass flow t h r o u g h a vent where t h e i n d o o r air t e m n e r a t u r e is t h e
same as t h e o u t d o o r t e m p e r a t u r e . T h e fi~ure is f o r m u l a t e d by
keeDin~ all Darameters c o n s t a n t ex ceDt t h e t e m p e r a t u r e rise of t h e
s m o k e [aver.
An e x a m o l e of t h e limitations of n a t u r a l vents d u e to o u t d o o r
t e m p e r a t u r e is indicated in Figure 2-3.3(~;). In this example, an
o u t d o o r t e m n e r a t u r e of 100°F~($8°C) is a s s u m e d . T h e s m o k e layer
t e m n e r a t u r e versus clear heit~ht is d e t e r m i n e d bv the e u u a t l o n for
t e m n e r a t u r e rise (A-t) in t h e uDDer laver for a vented fire (see TaMe
3-5). for t h r e e fires with different h e a t release rates. W h e r e t h e
s m o k e laver t e m p e r a t u r e is less t h a n t h e o u t d o o r t e m p e r a t u r e , n o
e x h a u s t is expected. As such• natural v e n t i n u is n o t a viab|¢
m e t h o d o f s m o k e m a n a u e m e n t for a 2500 B t u / s e c (78 kW) fire
where t h e i n t e n d e d cleat" h e i u h t is L~reater t h a n 60 ft (18 m),
Similarly. clear heiuhts ~reater thar~ 80 f t a n d 90 ft (24 m a n d 27 m)
618
NFPA 92B ~
MAY 2000 ROP
N O T E ; Only algebraic calculation m e t h o d s are discussed with
regard to each of t h e desitm a p p r o a c h e s listed in Table 2-4.1. Scale
m o d e l i n g , c o m p a r t m e n t fire m o d e l s (zone m o d e l s L or
c o m p u t a t i o n a l fluid d y n a m i c s ( C F D ) m o d e l s can be u s e d to
d e m o n s t r a t e each as outlined elsewhere in this d o c u m e n t .
c a n n o t be achieved with natural v e n t i n g for t h e 5000 B t u / s e c a n d
7~00 B t u / s e c (155 kW a n d 235 kW) fires.
LL
o
2500 Btu/sec
-- 5000 Btu/sec
600
tt
---
500"
~
~
......
~
2-4,1,1 S m o k e Filling V e r s u s T i m e d _Egress Analysis. A m e t h o d for
r e m o v i n g s m o k e f r o m a large-volume space is n o t necessarily
n e e d e d if it can be d e m o n s t r a t e d that o c c u p a n t s are able to egress
the ~pace safely before t h e s m o k e layer d e s c e n d s to t h e p o i n t at
which t h e o c c u p a n t s are exposed to t h e smoke. Exposure can be
in terms of p r e s e n c e of s m o k e or tenability of t h e e n v i r o n m e n t to
which o c c u p a n t s are exposed.
7500 Btu/sec
Outdoor temperature
400
~_ s00
~',~,,
200
A ¢otaservative estimate o f t h e position o f t h e s m o k e laver is t h e
first indication o f smoke, as s h o w n in Figure 1-4. a n d as calculated
u s i n g t h e empirically derived Equations (3) a n d (4) in Section 3-6.
E q u a t i o n (3) applies to steady fires, a n d Equation (4) applies to
unsteady fires, as d e f i n e d in Section 3-2. Equations (3) a n d (4)
implicitly a c c o u n t for t h e t r a n s p o r t lag associated with t h e
m o v e m e n t of s m o k e f r o m t h e fire into t h e u p p e r layer.
100
0
I
I
0
I
l
20
I
I
40
I
60
I
I
80
I
I
100
I
120
I
I
I
140
Clear height (ft)
Figure 2-3:3 Limitations of natural vents due
to outdoor temperature.
2-4 D e s ~ n A p p r o a c h e s . T h e design options available for t h e
dr;sign of ~mok~ m a n a g e m e n t d e p e n d on t h e space in which t h e
s m o k e is to be m a n a g e d a n d t h e space in which s m o k e ori~nates.
as described in 2-4.1 a n d 2-4.2. T h e design m e t h o d , if any• for
r f m o y i n g s m o k e f r o m a space ( m e c h a n i c a l e x h a u s t versus natural
venting) or corltailaing s m o k e to i~ space (airflow m e t h o d versus
pl'essurizafion m e t h o d ) n e e d s to be considered.
~-4.1 Managemgllt o f S m o k e in a Large-Volume Space. A n u m b e r @:.::::.,
o f acceotable m e t h o d s exist for m a n a g i n g s m o k e from a fire
"i#~
originating in a large-volume snace. Table 2-4.1 s u m m a r i z e s t h e
'?:i-':'::
basic design considerations for-each of these m e t h o d s , which
":i~
i n c l u d e t h e following:
::~::::.-':.'.-".:~.::::.:~
~i:'~:?::'~::,
... .:..
.
.
.
.
,:i-i~:
%"
( a ) U u h z m g t h e large-volume space as a s m o k e r e ~
r an.d..-:ii~.:~::...~
~
m o d e l i n g s m o k e laver d e s c e n t tO d e t e r m i n e whetheU~h'~il ~o~:"":"-"-'-"-:~::'.~i::
laver interface r¢~ches a h e i g h t at which o c c u n a n t s are e~ ~
to '*:"-:*-~
~llaoke before they are able to egress f r o m t h e ~':~:i:~:~.
"-:?.-:!:-:.~!!-~. ¢,~
(b) Removitlg Smoke f r o m t h e l a r g e - v o l ~ " s n a c e ' ~
r a "::!'!iii~
-~!;:'::
~ e c h a m c a l e x h a u s t c a o a o t v sufftcmnt tO.~t~ntaln t h e gi~ ake I ~ e r
Interface at a n r e d e f i n e d h e m h t m t h e soace~l::.an mdefi iSte
period of time.
"~":$~. . . .
sff
"(c~ ~emoving smoke from the ~ g e - v o l u m e s ~ k : . ~
a
Eauation (3) c a n n o t be c o m b i n e d with Equation (4) to calculate
laver ~l¢~cent for ~ n g
fires with a steady-state m a x i m u m . Each
of these e q u a t i . ~ ' l s ' ~ i r i c a l l y
derived a n d c a n n o t be u s e d in
c o m b i r l a t i o n ~ - ~ ' t h e other. Calculation of laver d e s c e n t for
growing f i ~ ( w i t ~ ) L t e a d v - s t a t e m a x i m u m s h o u l d be a c c o m n l i s h e d
in a m ~ a ~ m i l a ? : ~ ' : ' t h a t
described in Section 2-4.1.$.
..:&::.::::~:~:~.-.,-:~
-%-.:::.:~ .~:..~..;~. "-~:.
":~.~g.
24~!'2 S m o k e Exhaust ~:"Achieve Constant Laver Height. A
~..egr~.analvsis
n~:~d n o t be n e r f o r m e d if'it can be s h o w n that
the "~::~'~v
interface is m a i n t a i n e d at a h e i g h t s o as to n o t
C X O O S ~ : ~ 0 a n t s tO s m o k e for a n indefinite he-rind of time. This
is accom~i~t~edP'ff a n e x h a u s t canacitv eoual to t h e volumetric
~ r . o d u c t i o n ' ~ ' s m o k e at t h e design laver interface h e i g h t is
~,:¢-gtated
otherwise, t h e v o l u m e of s m o k e bei-ng i n t r o d u c e d
i~:to ~ m o k e
laver is equal to t h e v o l u m e of s m o k e being
r e m o ~ d by t h e m e c h a n i c a l exhaust• In general, this m e t h o d
t~lies strictly to steady fires, unless t h e oeak volumetric s m o k e
9 ~ 1 3 ~ o n is known for an u n s t e a d y fire-over t h e design p e r i o d of
s m o k e m a n a g e m e n t system operation. T h e volumetric s m o k e
woduction rate at a given laver interface h e i g h t can be calculated
u s i n g Equations (8). (9). (10). a n d (15). T h e t e m p e r a t u r e o f t h e
s m o k e e n t e r i n g t h e layer• calculated u s i n g t h e e q u a t i o n s in Table 35. n e e d to be a c c o u n t e d for in calculating t h e s m o k e density u s e d
[ ~ ¢ ~ e Equations (~), (9). (10L an0, (15~ reference an interface
h e i g h t c o r r e s n o n d i n g to t h e top of t h e transition zone shown in
Figure 1-4. a design interface h e i g h t n e e d s to be selected that
eilsurcs that o c c u p a n t s are n o t e x p o s e d to smoke• W h e n selectirq_
this design interface h e i g h t , the expected d e p t h of t h e transition
zone [leeds to be considered.
llqechamcai e x h a u s t c a p a o t y that slows t h e rate o f g ~ k e laver
d e s c e n t for a Defied that allows o c c u o a n t s to safelv:"~ress f r o m the
(d) Providing natural v e n t i n g sufficient to m a i n t a i n t h e s m o k e
layer interface at a n r e d e f i n e d h e i g h t in t h e space for a n indefinite
period of time.
(e) Providing llatural venting sufficient to slow the rate of s m o k e
layer d e s c e n t for a period that allows o c c u p a n t s to .~afely e t r e s s
f r o m t h e space.
Exposure can be in terms of presence of s m o k e or tenability o f
the e n v i r o n m e n t to which occupants are exposed•
T a b l e ~[-~.1 Large Volulge S race Smok~ Control Method~
5 o
"
v
" e
s.
~moke Transvort
~Iculatiolls
See NFPA 204
hint Necessary
"
st2agr_ady_y_~
•
"
U
.
.
.
.
.
~teadv
Natural Venting with C o n s t a n t Laver H e i g h t +
Natu
I Ve ti
vs.
"
s
s"
~
Unsteadv Fire
See NFPA '204
t An u n s t e a d y fire is n o t an notion for this a n o r o a c h because only a steady fire results in a constant laver height.
619
~_qraur~
N F P A 92B - - MAY 2000 R O P
2-4.1.3" S m o k e E x h a u s t V e r s u s T i m e d ~
Analvsls. S m o k e
exhaust can be used to slow the rate of s m o k e laver d e s c e n t for a
t)eriod that allows o c c u n a n t s to safely e~ress f r o m a snace. This
a n n r o a c h can be u s e d where it is n o t possible to nrovide a n
exiaaust canacitv sufficient to m a i n t a i n s m o k e at a-desima interface
laver for axa i n d e f i n i t e n e r i o d of time. In o r d e r to calculate t he
s m o k e laver Position over time. a t r a n s i e n t analysis n e e d s tO be
n e f f o r m e d tfiat takes into a c c o u n t the c h a n g e in s m o k e n r o d u c t i o n
as a f u n c t i o n o f th e Dosition of the s m o k e laver i n t e r f a c e as well
the s m o k e removal t~rovided bv a m e c h a n i c a l s m o k e e x h a u s t
system. This a n n r o a c h is discussed in detail in A-2-4.1.3.
E o u a t i o n s (8). (9). (10). a n d ¢15) are used in to d e t e r m i n e th¢
v olumetric i n n u t of s m o k e into the s m o k e laver for a ~iven t i me
steo. A specified a u a n t i t v of m e c h a n i c a l s m o k e e x h a u s t is t h e n
removed ~ o m the s m o k e laver over the same t i m e sten. T h e new
laver o ositio n at t h e e n d of t h e t i m e sten is t h e n calculated. T h e
t e m p e r a t u r e of t h e s m o k e e n t e r i n g the laver, calculated us i ng t he
eouafions in Table 3-5. m u s t be a c c o u n t e d for in calculatin~ th¢
s m o k e density used in E o u a t i o n (22). Transt)ort lag associg~fd
with the m o v e m e n t of s m o k e f r o m the fire into t h e Ut)Der laver may
or may n o t be i n c l u d e d in this analysis. Imaoring t r a m D o r t ]a~
fields a m o r e conservative result as the smoke is ] n s t a n t ~ e o u s l y
a d d e d to the u p p e r laver, r e s u l t i n g in a m o r e ranid layer descent,
T h e t r a n s n o r t lag may be at)t)r eciable when c o n s i d e r i n g fir¢~ irl
s o a c e s with l a r g e areas.
--
~3] P rovi di ng a n o n n o s e d airflow over t he face of t h e o o e n i n g to
t)rohibit s m o k e s n r e a d i nt o t he c o m m u n i c a t i n g soace
(4) Promt)tlng sut)t)ression of t h e fire to ternainate the
d e v e l o n m e n t of a h e a t e d s moke 9lt~me
2-4.1.6.1 S m o k e e x h a u s t can be t)rovided within t h e large-volume
space to l i mi t t h e d e n t h of s m o k e a c c u m u l a t i o n , or in cr eas e t h e
time for s m o k e fillin~ within t h e large-volume soace, so th at t h e
s m o k e laver i n t e r f a c e r e m a i n s above-the level ol~t he h ig h es t
ot )e ni ng to c o m m u n i c a t i n g spaces for t h e t i m e necessary to achieve
~ e de s i gn objectives. T h i s t e c h n i o u e m i g h t n o t be co m p letely
effective if t he source of t he fire is clirectlv a d l a c e n t ~9 ~ ¢
c o m m u n i c a t i n g st)ace. Thi s m ) o r o a c h might- n o t be feasible for
c o m m u n i c a t i n g spaces in t he u p p e r t)ortion of t h e largf-vo|~pae
2-4.1.6.2 Smoke barriers can be orovi de d to l i mi t s m o k e s p r ¢ ~ i
into t he c o m m u n i c a t i n g st)ace. D e n e n d i n g on t he e x t e n t o f
o n e n i n g s in t h e barrier~ a t)ressure d i f f e r e n t i a l ma y n e e d to be
a n o l i e d - a c r o s s t he s m o k e barrier. Thi s m e t h o d is discussed in
I~bqPA 92A. Recommended Practice for Smoke-Control S~steras. A
t)ressure differential can be a c hi e ve d bv e x h a u s t i n g th e large-
Because E o u a t i o n s (8). (9). (10L a n d (15) reference a n interface
h e i g h t c o r r e s o o n d i n g to the too of the transition zone shown ill
Figure 1-4. a d e s i g n interface h e i g h t n e e d s to be selected t h a t
ensures t h a t o c c u o a n t s are n o t e x o o s e d to smoke. W h e n selectjt3g
this desima interface h e i g h t , the e x n e c t e d d e n t h of t h e transition
zone n e e d s to be considered.
Ext)osure can be in terms of t)resence of s m o k e or tena bi l i t y of
the e n v i r o n m e n t to which o c c u o a n t s are exoosed.
2-4.2 M a n a g e m e n t o f S m o k e Wi t hi n C o m m u n i c a t i n g Sp~¢~8,
24.2.1 Fire in Spaces S u r r o u n d i n g a I a ~ e - V o l u m e Spact h
Possible c o n f i t a l r a t i o n s for t h e relationshi-n b e t w e e n th e largfv o l u m e snace a n d t he s u r r o u n d i n g s o a c e s - i n c l u d e t h e following.
(1) S e o a r a t e d soace
(2) C o m m u n i c a t i n g snace
2-4.2.2 Fh'e in Setmrated_ Snaces. W h e r e c o n s t r u c t i o n eep ar atin g
t h e large-volume snace f r o m t he s u r r o u n d i n g areas is suflficientlv
tight s o t h a t t h e pre s s ure differences b e t w e e n - t h e fire zo n e a n d th e
n o n f i r e zones can be contxolled, t h e large-volume snace can b e
t r e a t e d as o n e of t h e zones in a z o n e d s moke -c ont r o l sy~ggrn.
Z o n e d s m o k e - c o n t r o l svstems a r e d e s c r i b e d i n NFPA 92A.
t h a t snecified in 2-4.1.3 so as to slow t h e rate of s m o k e laver
d e s c e n t for a n e r i o d that allows o c c u o a n t s to safely e~ress f r o m a
st)ace. This a-ooroach can be u s e d w h e r e it is n o t oossible to
nrovide m e c h a n i c a l e x h a u s t or natural v e n t i n g of sufficient canacitv
to m a i n t a i n s m o k e a t a d e s i g n interface laver for an i n d e f i n i t e
t)eriod of time. In o r d e r to calculate t h e s m o k e laver oos i t i on over
time. a t r a n s i e n t analysis n e e d s to be n e r f o r m e d t h a t take~ il~t9
a c c o u n t the c h a n g e in s m o k e t)roduction as a f u n c t i o n of t he
nositlo n of t h e s m o k e laver i n t e r f a c e as well as t h e s m o k e re mova l
t)rovided bv n a t u r a l venting. A similar a n n r o a c h is discussed in
detail for m e c h a n i c a l e x h a u s t (see A-2-4.1.3 ). T h e v o l u m e t r i c
s m o k e removal n r o v i d e d bv natural v e n t i n g can be calculated u s i n g
m e t h o d s o u t l i n e d in N F P A 204. Guide for Smoke and Hea¢ Vgntn~.
Recontmend~ Practice for Smoke-Control S~stems.
2-4.2.3 F'we in C o m m u n i c a t i n g Snaces. C o m m u n i c a t i n g spaces
can be d e s i g n e d to allow t he s m o k e to snHI i nt o t h e large-volume
snace. In tills instance, t h e s m o k e s v i l l i n g i n t o t he lar~e-vpltamf
snaee s h o u l d be h a n d l e d by t h e s m o k e m a n a g e m e n t system, which
is n r o v i d e d to m a i n t a i n t he desRm s m o k e laver interface height.
C o m m u n i c a t i n g snaces can also-be d e s i t m e d to n r e v e n t th e
m o v e m e n t of s m o k e i n t o t he large-volume snace. S u ch a ~f~it~n
w oul d r e o u i r e sufficient e x h a u s t f r o m t h e c o m m u n i c a t i n g space s o
as to establish a m i n i m u m flow b e t w e e n i t a n d t h e large-volume
v
2-4.1.6 M a n a g e m e n t o f S m o k e S n r e a d t o C o m m u n i c a t i n g St)aces.
M a n a g e m e n t o f s m o k e s v r e a d to c o m m u n i c a t i n g st)aces m a y be
accom-olished by o n e o f ' t h e following m e t h o d s : - -
_
(1) M a i n t a i n i n g the s m o k e laver interface at a level h i g h e r t h a n
t h a t of the h i g h e s t o o e n i n g to the c o m m u n i c a t i n g SlP~,¢¢
2-4.2.3.1 E x h a u s t T h r o u g h a Large-Volume S n a c e . For fires in
u n s D r i n k l e r e d svaces, t h e e x h a u s t rate f r o m t he large-volume sDace
n e e d s to be evaluated n o t only for a free n l u m e fro m a fire in th e
large-volume s na c e b u t also for a n l u m e ork, i n a t i n g in t h e
(2) Providing a s m o k e b a r r i e r to limit s m o k e s n r e a d into t he
c o m m u n i c a t i n g snace (A nressure differential may n e e d to be
a o n l i e d across t h e s m o k e b a r r i e r . )
620
N F P A 92]8 - - M A Y 2 0 0 0 R O P
c o m m u n l c a t i n ~ suace. T h e s m o k e m a n a g e m e n t system s h o u l d h e
able to h a n d l e - e i t h e r condition, b u t n o t I ~ t h simultaneonsiv. T h e
m e t h o d s for calculating t h e volumetric s m o k e o r o d u c t i o n f o r soill
v l u m e s a n d window ~ l u m e s a r e discussed in $-8.9 a n d ~8.$.
resnectiv~lv. T h e em~ations in ~-8.~ a n d $-8.g are only valid for
f i r ~ in uiasnrinklered snaces as t h e y w e r e d e r i v e d empirically ~rom
test data.! (3~ce s m o k e e n t e r j t h e large-volume snace, t h e
~ll}~2~L~[~smoke
c u d i n ~ b a c k - o n t o u n n e r f l o o r s or
i m n i n ~ i n ~ o n o v e r h a n t 6 n g ceilings o f u o o e r t ] o o r s exists a n d
s h o u l d be cousidered.-TlT~ere is a nossil~i-litv t h a t this maoke will
e n t e r u p p e r floors o f c o m m u n i c a t f n ~ s_nacea, a n d t h f hazard this
s m o k e mit~nt or m i g h t n o t p r e s e n t t 9 t h e s e epaces s h p u | d be
e~uated.
s u r e a d l r ~ m areas outside t h e large-volume fa3ace. T h e following
events n e e d to occur to accomnlls-h t h e s e m ~ l s .
(a~ T h e fire n e e d s to be d e t e c t e d early t'before t h e s m o k e level or
rate o f d e s c e n t exceeds~the d e s i g n oblecfivesL W h e r e t h e s m o k e
m a n a g e m e n t system is n r o v i d e d - t o assist safe e v a c u a t i o n o c c u n a n t
reaction time t'o t h e en~-r~encv a n d e ~ c o a t i o n t i m e s h o u l d ! ~
(b) T h e HVAC s s s t e m serving t h e large-volume suace a n d
c o m m u n i c a t l n ~ s n a r e s n e e d s to" be s t o p p e d ff its 01~ecation would
adversely affec~ tl~e s m o k e m a n a g e m e n t s ~ t e m .
(c] S m o k e s h o u l d be r e m o v e d - f r o m t h e l a r t ~ v o l u m e space
above t h e d e s i r e d s m o k e laver interface.
(d] Sufficient m a k e u n air s h o u l d be nrovided to satisfy t h e
exhaust. It is essential flint t h e m a k e u n air s u n , I v inlet a n d t h e
e x h a u s t outlet be s e n a r a t e d so t h a t t h e contan-~nated air is n o t
drawn into t h e buiiclinm
2-4.2.3.2 C o n t a i n m e n t o f S m o k e to C o m m u n l c a t i n ~ Snaces.
C o m m u n i c a 6 n g soaces c a n also be deslt,n e d to orevent t h e
m o v e m e n t o f s m o k e into t h e large-volume rmace. Such a denims
w o u l d r e n u i r e sufficient e x h a u s t f r o m t h e c o m m u n i c a t i n g spac¢ s o
as to e s t a ~ i s h a m i n i m u m flow between it a n d t h e large-volume
svace. T h e face velocltv across t h e face a r e a of t h e o ~ n l n g that
achieves this is described in 2-4.1.6.$. a n d C h a n t e r $ ~rovic[e~
calculation m e t h o d s for s m o k e g e n e r a t i o n in t h e c o m m u n i c a t l n ¢
soace. T h e e x h a u s t ouantitv ne~-ssarv for this situation can re,early
exceed t h e canacitv of t h e n o r m a l b u i l d i n g HVAC s~Tl:lI~ a n d can
r e u u i r e t h e installation o f a d e d i c a t e d smo~ke n m n a o e m e n t system
f o r - t h e c o m m u n i c a t i n g soace.
2-5.2 A u t o m a t i c Activation. T h e confkruration o f t h e l a r ~ - y o l u m e
snace s h o u l d be c o n s i d e r e d in selectin~ t h e .type o f d e t e c t o r to be
to activate t h e s m o k e m a n a g e m e n t s m t e m . T h e size. sha~e.
a n d h e i g h t o f t h e s n a c e n e e d to be evaluated. ; t h e s e factont ~ - v
T h e n l a c e m e n t of t h e e x h a u s t o o e n i n ~ s h o u l d h e evaluated
carefu|lv. E x h a u s t intake a n d d i ~ h a r t , e~oneninaa s h o u l d be
l o c a t e d so t h a t s m o k e m o v e m e n t will n o t interfere with exit~ T h e
location o f t h e e x h a u s t discharge to t h e outside s h o u l d be located
away f r o m outside air intakes to m i n i m i z e t h e likelihood o f s m o k e
b e i n ~ recircolated. S m o k e barriers can also be provided between
t h e large-volume m a c e a n d c o m m u n i c a t i n g suaces. W h e r e
c o n s t r u c t l o n semr~fin~r t h e l a r t ~ v o l u m e st~ace f r o m t h e
s u r r o u n d i n ~ ar~as is sufficlently tlgh t s o t h a t t h e presm,tre
Control S~stems.
2~;.2.2 Normally. all a u t o m a t i c d e t e c t i o n devices within t h e lamev o l u m e snare_ a n d c o m m u n i c a t i n g _maces s h o u l d activate the,
s m o k e m a n ~ e m e n t sVW'rfi. Detpctors for fo,,~-ial nurDose~ s u c h
as elevator recall a n d d o o r r e l , ' ~ P a n d for -_~poc;6c bar~rds~ liceh
as s u e d a l fire-extin~ulshlng a ~ J e m L can h e e x c e n f i o m . In o r d e r
to avoid unnecmsarTv oner-a~ti0n o f t h e system f r o m s m o k e d ~ t p e t o r
activation, consideration s h o u l d h e t,lven to activatin~ t h e matem by
two or m o r e s m o k e detectors or on-alarm-verlfication.
A u t o m a t i c d e t e c t i o n devices s h o u l d n o t h e connert,-d directly to
t h e s m o k e m a n a ~ , e m e n t s w t o m w i t h o u t fiirther c o n c e r n for tht;
inte~rltv of t h e detection system. Intem4t¢ o f t h e det,-cti0n system is
c o n s i d e r e d in t h e analysis i n d u d e t h e following:
(3~ S m o k e t e m o e r a t u r e
• 4LY..~ Snot.tvne s m o k e detectors can be mu~! o n or n e a r low
ceilinwa o f l a ~ e - v b l u m e snares, n r o v l d e d t h a t t h e d,.t,.ctora are
a c c e ~ b l e for-servicln~ a ~ ! n o s i t l o n e d ~
o n consideration o f
t h e effects o f stratifies/ion a n d air c u r r e n m ~nu,¢l ~ n~ttnrai mad
T h e d e t e r m i n a t i o n o f s m o k e toxicity usually includes t h e anal@i~
o f e x o o s u r e to c a r h o n m o n o x i d e f C O L F x r u ~ u r e to o t h e r fneJd e o e n d e n t toxic wages can also b e considered. Ten~h;~i¢/limits for
b o t h s m o k e toxicity, a n d s m o k e tem_~u,m~r ~ nam~llv con~id~r t h e
time o f e x n m u r e to t h e smoke.
mtghaaL~.fam~
2~;.2.4 Projected b e a m 4 v n e s m o k e detectors can be u s e d on or
T h e calculations n e r t a i n i n ~ to t h e d e t e r m i n a t i o n o f visibili W
distance a r e cliscu~ed in A--~-5. An evahmtlon o f t h e effects o f
s m o k e on n e o n l e d u e to s m o k e toxicity a n d s m o k e t e m n e r a m r e is
outside t h e s c o u e o f this tmide. However. as statPd in I-5.6. o t h e r
references are available t h a t n r e s e n t analvtlcal m e t h o d s for
ten~thilltv ~m~t|vges [~41.
n e a r h ~ h c e i l i n ~ o f lar~g-volume s n a r e s a n d po*itlnned to m'olect
t h e b e a m horlzontallv o r i n o t h e r accentable orientatiom~
SUmltlcation a n d natural o r m e c h a n i c a l air c u r r e n t s can n e e m l t ~ t ~
t h e u s e o f addltional ~roiected b e a m s at i n t e r i m levels o f t h e l a r ~ v o l u m e s n a c e w h e r e c,eillnc, heiMats would contribute to t h e delay
in initiating_ smoig¢ m a n a c e m e n t ~
9.fi S m o k e Manam~naent S v s m m O n e r a t i n n .
2~.2.5 A u t o m a t i c surinkler water flow s h o u l d a l ~ be u s e d to
activate t h e s m o k e m a n a g e m e n t ~ t ~ ' n . It is i m n o r m n t t h a t tho
surinkler s~tmla h e z o n e d with t h e s m o k e d e t e c t i o n s~at*pm i n t h e
i~trge-volume s n a c e so that t h e correct s m o k e m ~ e m e n ¢
r e s n o u s e is effected. T h e hei~dht o f t h e large-volume *paCe a n d the-
24L! s m o k e n m n a ~ e m e n t m~tems for large-volume s_rme~ a r e
i n t e n d e d to restrict t h e s m o k e laver to t h e u n n e r o o r t i o n o f t h r
large-volume snace or to limit t h e a m o u n t o-f-smc~ke f r o m
621
NFPA 92B -- MAY 2000 ROP
location of snrinklers s h o u l d be analyzed in o r d e r to estimate
snrinkler activation r e s n o n s e time. Snrinkler activation time o n be
too slow to effectively initiate s m o k e m a n a g e m e n t where snrinlders
are located several stories above t h e floor of t h e snace. Tl~e
e a u a t i o n s of C h a n t e r ~ s h o u l d be u s e d to analyze eaqh case.
Snrinlder water flow s h o u l d nevertheless be o n e of t h e s m o k e
m a n a g e m e n t svstem initiating m e a n s , even if only as a b a c k u p
system. Snrinkler activation can nrovide an effective t~rimarv
initiation m e a n s w h e r e sorinklers are located on lower ceilings.
"Each a p p r o a c h h a s values a n d limitations. N o n e is totally
satisfactory. While t h e results o b t a i n e d f r o m t h e different
a p p r o a c h e s s h o u l d normally be similar, they are n o t usually
identical. T h e state of t h e art involved, while advanced, is
empirically based, a n d a final t h e o r y p r o v a b l e in f u n d a m e n t a l
physics has n o t yet b e e n developed. T h e core of each o f t h e
calculation m e t h o d s is based o n t h e e n t r a i n m e n t of air (or o t h e r
s u r r o u n d i n g gases) into t h e rising fire-driven plume. A variation of
approximately 20 p e r c e n t in e n t r a i n m e n t occurs between the
empirically derived e n t r a i n m e n t e q u a t i o n s c o m m o n l y used, such as
those indicated in this chapter, or in zone-type c o m p a r t m e n t fire
models. Users m i g h t wish to a d d a n appropriate surety factor to
e x h a u s t capacities to a c c o u n t for this uncertainty. A brief
discussion o f t h e values of t h e several a p p r o a c h e s follows.
2-5.3 Manual Activation. A m e a n s of m a n u a l l y startin~ a n d
s t u n n i n g t h e s m o k e m a n a g e m e n t system s h o u l d be located so as to
be -accessible ~o t h e fire d e n m x m e n t .
3-1.1.1 Scale Modeling. Scale m o d e l i n g is especially desirable
where t h e space b e i n g evaluated has projections or o t h e r u n u s u a l
a r r a n g e m e n t s t h a t p r e v e n t a free-rising p l u m e . In a scale model,
t h e m o d e l is normally p r o p o r t i o n a l in all d i m e n s i o n s to t h e actual
building. T h e size of t h e fire a n d t h e interpretation of the results
are, however, g o v e r n e d by t h e scaling laws, as given in 3-1.2.
A l t h o u g h s o u n d , t h e a p p r o a c h is expensive, t i m e - c o n s u m i n g , a n d
valid only within t h e r a n g e o f tests conducted. Because this
a p p r o a c h is usually reserved for c o m p l e x structures, it is i m p o r t a n t
that t h e test series cover all o f t h e potential variations in factors
such as position an d size of fire, location a n d capacity of e x h a u s t
a n d intake f l o w s , . . , . ~ o m in internal t e m p e r a t u r e (stratification
or floor-ceilin.~.~..~pi~ture gradients), a n d o t h e r variables. It is
likely t h a t ~ : : . w i l l
n o t be appralsable u s i n g scale models.
2-6 S m o k e Manastemeut System Reliability.
2-6.1 Fault Analysis. Every s m o k e m a n a g e m e n t system s h o u l d I~¢
subjected to a fault analysis so as to determine: t h e irqpact Of a
failure, i m n r o o e r onerafion, or partial o n e r a t i o n of e~ch m a j o r
svstem c o m n o n e n t on i n t e n d e d svstem oneration. O f parti~;ul~r
c o n c e r n are those systems t h a t are i n t e n d e d t9 maintgin a nr¢~sure
or flow balance between adiacent soaces to control t h e m o v e m e n t
of smoke. S h o u l d it be f o u n d that i_he faulty ooeration of a
c o m n o n e n t will cause reversal o f the s m o k e flow or lowering o f t h e
smol~e interface laver to d a n g e r o u s levels, t h e d e g r e e to which its
o n e r a t i o n can be r e d u c e d a n ~ t h e prgbabili~y of s u c h occurr~oce
sfiould be d e t e r m i n e d .
3-1.1.2 ~ . r a i c " ' ~ i o n s .
Algebraic equations, as c o n t a i n e d in
this g ~ ' ~ d e
afS~_o._.~ m e a n s o f calculating individual
f a c t ~ that ~ ' b l l e c t i . . . 1 . ~ - - ~ e u s e d to establish t h e design
rr,e ~ r e m ~ ' ~ a t s of a s m o l ~ " h m n a g e m e n t system. T h e equations
t~..~ed.~
c o n s i d e r e d to be t h e m o s t accurate, s,mple,
alge"~xpl~ssmns
available for t h e p r o p o s e d purposes. In
ge~ner~..~.~y are limited to cases involving fires that b u r n at a
c o n s t a n t ° ~ . . . ~ h e a t release ("steady fires" as described in 3-2.2) or
~ . ~ s that ir i : ~ a s e in rate o f h e a t release as a f u n c t i o n of t h e square
.~.~.~'steady
fires" as described in 3-2.3). T h e equations are
~ 7 $ ' ~ $ i ' p r i a t e for o t h e r fire conditions or for a condition that
~:nitial~'grows as a f u n c t i o n of t i m e b u t after r e a c h i n g a m a x i m u m ,
b u r n s at a steady state. In m o s t cases, j u d i c i o u s use o f t h e
ations can reasonably overcome this limitation. Each of t h e
ations h a s b e e n derived f r o m e x p e r i m e n t a l data. In s o m e
cases, t h e r e is only limited test data a n d / o r t h e data h a s b e e n
collected within a limited set o f fire sizes, space d i m e n s i o n s , or
points of m e a s u r e m e n t . W h e r e possible, c o m m e n t s are included
o n t h e r a n g e of data u s e d in deriving t h e e q u a t i o n s presented. It is
i m p o r t a n t to consider these limits.
Caution s h o u l d be exercised in u s i n g t h e equations to solve t h e
variables o t h e r t h a n t h e ones p r e s e n t e d to t h e left of t h e equal sign,
unless it is clear how sensitive t h e result is to m i n o r c h a n g e s in any
of t h e variables involved. W h e r e these restrictions p r e s e n t a limit
that obstructs t h e users' needs, consideration s h o u l d be given to
c o m b i n i n g t h e use of equations with either scale or c o m p a r t m e n t
fire models. Users of t h e equations s h o u l d appreciate t h e
sensitivity of c h a n g e s in t h e variables b e i n g solved for.
2-6.2 ll.eliabiUty. Reliability of t h e s m o k e m a n a g e m e n g s y s t e ~
d e n e n d s o n t h e soecific reliabilitv of t h e individual c o m n o n e n t s .
functional d e p e n d e n c e o f t h e c o m n o n e n t s on o n e a n o ~ e r , a n d
d e g r e e of r e d u n d a n c y . Reliability of t h e individual c o m n o n e n t s
(i,¢,, hardware, softwi~re, a n d interfaqes with 9 t h e r sv~ems~
involves both their n e r f o r m a n c e d u r i n g n o r m a l o n e r a t i n g
conditions as affected bv e n v i r o n m e n t a l factors, over the-life of t h e
system, a n d their ability to withstand t h e stresses e n d u r e d durin~r a
~
t h e system is onerational a n d will reliably n e r f o r m w h e n n e e d e d .
M e a n s s h o u l d be nrovided for o e r f o r m i n ~ - n e r i o d i c tests of t h e
smok~ m a n a g e m e n t system in order to verify t h e systerq
pefformance~ Systems s h o u l d be d e s i g n e d to p e r m i t t;¢sting
without any snecial e u u i D m e n t o t h e r t h a n what is provided with t h e
Because access for n e r f o r m a n c e verification m e a s u r e m e n t s
is oft~la difficult, it is glesiral~l¢ that. where possible.
i n s t r u m e n t a t i o n be comnletelv built-in or partially built-in a n d
nartiallv nrovided as portable monitors.
3-1.1.3" C o m p a r t m e n t Fire Models. C o m p u t e r capabilities
sufficient to execute s o m e of the family of c o m p a r t m e n t fire
m o d e l s are widely available. All c o m p a r t m e n t fire m o d e l s solve t h e
conservation e q u a t i o n s for distinct r e g i o n s (control volumes).
C o m p a r t m e n t fire m o d e l s can be generally classed as zone m o d e l s
or f i e l d - ( c o m p u t a t i o n a l fluid dynamics-)- (CFD) models.
3.1.1.$.1 Zone Models. Z o n e models are t h e s i m p l e r m o d e l s a n d
can usually, be r u n on personal computers. Z o n e m o d e l s divide
t h e space into two zones, a n u p p e r zone that contains t h e s m o k e
a n d h o t [~ases p r o d u c e d by t h e fire a n d a lower zone, which is t h e
source o t e n t r a i n m e n t air. T h e sizes of t h e two zones vary d u r i n g
t h e course of a fire, d e p e n d i n g o n t h e rate of flow f r o m t h e lower
to t h e u p p e r zone, t h e rate o f e x h a u s t o f t h e u p p e r zone, a n d the
t e m p e r a t u r e o f t h e s m o k e a n d gases in t h e u p p e r zone. B e c a m e of
t h e small n u m b e r o f zones, zone m o d e l s use e n g i n e e r i n g equations
for h e a t a n d m a s s traasfer to evaluate t h e transfer of mass a n d
e n e r g y f r o m t h e lower to the u p p e r zone, the h e a t a n d mass losses
from t h e u p p e r zone, a n d o t h e r features. Generally, t h e equations
a s s u m e that conditions are u n i f o r m in each respective zone.
In zone models, t h e source of the flow into the u p p e r zone is t h e
fire plume. All zone m o d e l s have a p l u m e equation. A few m o d e l s
C h a p t e r 3 Calculation P r o c e d u r e s
3-1 Introduction.
3.1.1 Design Approaches. T h r e e different s m o k e m a n a g e m e n t
system design a p p r o a c h e s are described as follows:
(a) Scale m o d e l i n g u s i n g a r e d u c e d scale physical m o d e l
following established scaling laws. Small-scale tests are c o n d u c t e d
to d e t e r m i n e t h e r e q u i r e m e n t s a n d capabilities of the m o d e l e d
s m o k e m a n a g e m e n t system.
(b) Algebraic, closed-form e q u a t i o n s derived primarily f r o m t h e
correlation o f large- a n d small-scale e x p e r i m e n t a l results.
(c) C o m p a r t m e n t fire m o d e l s u s i n g both theory a n d empirically
derived values to estimate conditions in a space.
622
NFPA 92B -- MAY 2000 ROP
allow t h e u s e r to select 3Jnong several p l u m e equations. Most
c u r r e n t zone m o d e l s are based o n a n axisymmetric p l u m e .
Because p r e s e n t zone m o d e l s a s s u m e that t h e r e is no pre-existing
t e m p e r a t u r e variation in v_he space, they c a n n o t direcdy h a n d l e
stratification. Z o n e m o d e l s also a s s u m e t h a t t h e ceiling s m o k e
layer forms instandy a n d evenly f r o m wall to wall. This fails to
a c c o u n t for t h e initial lateral flow of s m o k e across the ceiling. T h e
resulting error can be significant in spaces having large ceiling
areas.
Zone m o d e l s can, however, calculate m a n y i m p o r t a n t factors in
the course of events ( e . g , s m o k e level, t e m p e r a t u r e , composition,
a n d rate of descent) f r o m a n y fire that t h e user can describe. Most
zone m o d e l s will calculate the e x t e n t of h e a t loss to t h e space
boundaries. Several m o d e l s will calculate the impact of vents or
m e c h a n i c a l exhaust, a n d s o m e will predict t h e response
of heat- or smoke-actuated ,detection systems.
3-1.3 T h e r e m a i n d e r of this c h a p t e r presents t h e algebraic
equation-based calculation p r o c e d u r e s for t h e various design
parameters, as referred to in t h e previous sections. T h e calculation
p r o c e d u r e s r e p r e s e n t an accepted set of algebraic e q u a t i o n s a n d
related i n f o r m a t i o n available for this edition of t h e guide.
3-1.4 Establishment o f Two-Layer Environment. A delay in
activating e x h a u s t fans can allow s m o k e to d e s c e n d below the
design h e i g h t of t h e s m o k e interface. Initial s m o k e a c c u m u l a t i o n
at low levels can also be aggravated by initial vertical t e m p e r a t u r e
stratifications t h a t delay t r a n s p o r t o f s m o k e to t h e u p p e r reaches of
t h e large volume s p a c e . However, with t h e e x h a u s t a n d air
m a k e u p systems activated, a clear lower layer can be expected to
develop in a g r e e m e n t with t h e design assumptions.
3-1.5 SI Units. SI f o r m s of t h e equations c o n t a i n e d in this chapter
are p r e s e n t e d in A p p e n d i x D.
3-1.1.3.2 ~
CFD Models. CFD ~ - - ~ models, also referred to as
. . . . . . . . . : ^ ~ 1 ~..:.~ ~ . . . . . :~" (C.r~D~)field models, usually require
large-capacity c o m p u t e r workstations or m a i n f r a m e c o m p u t e r s a n d
advanced expertise to operate a n d interpret. CFD ~ ! ~ models,
however, can potentially overcome t h e limitations of zone m o d e l s
a n d c o m p l e m e n t or s u p p l a n t scale models.
As with zone models, C F D _ f i e ~ m o d e l s solve the f u n d a m e n t a l
conservation equations. In CFD field models, t h e space is divided
into m a n y cells (or zone.,;) :rod use the conservation equations to
solve the m o v e m e n t of heat a n d mass between t h e zones. Because
of t h e massive n u m b e r of zones, CFD field~ m o d e l s avoid t h e m o r e
generalized e n g i n e e r i n g equations u s e d in zone models. T h r o u g h
the use of small cells, C.CFDfield m o d e l s can e x a m i n e t h e situation
in m u c h greater detail aztd a c c o u n t for t h e impact or irregular
shapes a n d u n u s u a l air m o v e m e n t s that c a n n o t be a d d r e s s e d by
either zone m o d e l s or algebraic equations. T h e level of r e f i n e m e n t
exceeds that which can usually be observed or derived f r o m scale
models.
3-2 Design Fire.
3-2.1" All of t h e design calculations p r e s e n t e d in this g u i d e are
d e p e n d e n t on t h e h e a t release rate f r o m t h e fire. T h u s , as a first
step, the design fire size n e e d s to be identified. T h e design fire size
is d e t e r m i n e d based on a n e n g i n e e r i n g analysis of t h e
characteristics of t h e fuel a n d / o r effects i n d u c e d by a fire. In
addition, fires can he considered as steady or unsteady.
3-2.2 Steady F~.:~ ~ e a d y fire is d e f i n e d as a fire with a constant
h e a t release g~,-X{bs such, the fire is expected to grow qmckly to
s o m e l i m i t , : : i ~ . ~ u ~ x t e n s i o n is restricted either d u e to fire
control ~ e s
(~al
or automatic) or a sufficient separation
distan:¢~~~.~bustibles
being present
..
3-1.2.1" In this guide t h e e m p h a s i s o f scaling activities is placed o n
m o d e l i n g h o t gas m o v e m e n t t h r o u g h building configurations d u e
to fire. C o m b u s t i o n a n d flame radiation p h e n o m e n a are ig~:.~g.:...c:d.
Fire growth is n o t m o d e l e d . A fire n e e d s to be s p e c f f i e ~
of a steady or rime-varying h e a t release r a t e . . ~ . , : ~ : ~ * ~ . . . . :.."~i!!~::..:x.
3-2.2.2 Separation Distance. T h e design fire s h o u l d be
d e t e r m i n e d by considefin~ t h e type o f fuel, fuel spacing, a n d
configuration. T h e selection of t h e d e s i g n fire s h o u l d start with a
d e t e r m i n a t i o n of t h e base fuel package, that is, t h e m a x i m u m
probable size fuel package that is likely to be involved in fire. T h e
design fire s h o u l d be increased if o t h e r combustibles are within the
separation distance, R, indicated in Figure 3-2.2.2(a) a n d
d e t e r m i n e d f r o m Equation (1). Note that if t h e base fuel package
is n o t circular, an equivalent radius n e e d s to be calculated by
e q u a t i n g t h e floor area covered by t h e fuel package with that
s u b t e n d e d by a circle of t h e equivalent radius. T h e entire floor
area covered or i n c l u d e d between c o m m o d i t i e s s h o u l d be
considered in the calculations, for example, if t h e fuel package
consists of the f u r n i t u r e items illustrated in Figure 3-2.2.2(b), the
area of t h e fuel package includes that covered by t h e f u r n i t u r e as
well as t h e area between the f u r n i t u r e items.
T a b l e 3-1.2.2
Velocity
Total h e a t release rate
Convective h e a t release rate
Volumetric e x h a u s t rate
T h e r m a l properties of e n c l o s u r e
v,
= ~ ~
( t.lt~) '/~
(t,,Ig,~?/~
~:. ~ = Q,~~ #
.
.....
"
However, if tests for
~e prevailing ceiling h e i g h t show t h a t fire in the combustible
Laterial will be quickly s u p p r e s s e d with t h e installed sprinkler
protection, c o m b u s t i o n can be a s s u m e d essentially to cease w h e n
t h e sprinklers operate.
3-1.2.2 Based o n t h e relationships in Table 3-1.2.2, a sc'~.'{~,~.fl/i~lel'~.~
can be developed. T h e m o d e l s h o u l d be m a d e l ~ L e n o " ~ i
~
achieve t u r b u l e n t flow of t h e full-scale system~..,:~mm~X.:,c.x
relating full-scale conditions (F) to those i . ~ . ~ : c a l ~ l
pr~s=:':~(m)~O
~"
p r e s e n t e d in Table 3-1.2.2,
conditions exist.
x, = x F t ~,,/~'1 ":~i!i~""
T= = TF
.:i?.Y:"
Ap= = App ( IJlp)
.
* l~:~ect o f S p r i ~ e r s o n Fire Size. Unless t h e r e is reason
~":~ct:.-~:fire
will c o n t i n u e to spread after sprinkler activation,
t h e | ~ ~ . ~ f S~rinklers on t h e design fire size can be a c c o u n t e d for
by ass d ' ~ g t h a t t h e fire stops growing w h e n sprinklers are
actuated. ~ ' ~ e r
words, t h e design fire is t h e estimated fire size at
~:.¢.. momeri~g.-~tgfsprinkler actuation. It is a s s u m e d t h a t t h e fire
' : ~ . ¢ . S : . _ 4 6 b u r n at this size until t h e involved fuel is c o n s u m e d ,
~!~';~11er
effect of the sprinkler spray on t h e b u r n i n g process.
3-1.2 Scale Models.
G e o m e t r i c position
Temperature
Pressure difference
:.~
= ~
Q, ., ~..~- = Q~, O~3- ( t.lt,) ~/~
( t.,It, W ~
(kp~)~,., = ( kpO ~,j, (t.llF) °'~
where:
c = specific h e a t of enclosure materials (wall, ceiling)
k = t h e r m a l conductivity of enclosure materials (wall, ceiling)
l = length
Ap = pressure difference
Q = h e a t release rate
t = time
T = t e m p e r a t u r e ( a m b i e n t a n d smoke)
v = velocity
V = volumetric e x h a u s t rate
x = position
R=[Q/(12~tq")]
'/2
(1)
where:
R = separation distance from target to center of fuel package (ft)
Q = h e a t release rate from fire (Btu/sec)
q"
= incident radiant h e a t flux required for n o n p i l o t e d ignition
(Btu/fff . s e e )
~_ = density
c = convective
F = full-scale
m = small-scale m o d e l
w = wall
623
N F P A 92B
-
MAY 2000 R O P
-
:+ . . . . . . . . . . . . .
Hemisphere
~l,:V~:~n+
Element
:+
On ~*11
neellnnne;--^
oriented
-^1
I-.~+
Ill
. . . . .
. 3 ^ . : ~
+I~^
ra m+~ ~ A
/¢*++++
^--A
C^.
+^
t}+,,/c+~-++~
,i.+
. . . . . . . . . . .
.--.:J^--+;--I
C..^I
. . . . . . .
c.
+;.,^I..
.
3-2.5 M i n i m u m Desi~,n F i r e S i z e
Caution.
Des!~z~e~
+.~--+
C . . . . . . .
I ......
+ : ~ . . I
g . . . . . . . . . .
+k~+
.
.
.
.
*~1+
.
[C1
. . . .
+. . . .
.
1.-..~
cr ~m
k..^+:kl
....
....
,=ll
t.+
. . . . . . :. -. +. .". " ~ ^ ' ~
in t~c s~:cc, tkcrc~ 7 E m i ~ n g ~ c m t c + f . h c : t r c l c = e
...............
n-.'g~ . . . . . . - - - - " ^
m--n'.a!n d u r i n g "d~c lifc of " ~ c ~. .......:.~. . + : _ ~~, .e.~. ._. ^,, f i m c s o f .a.ay, da}~ of
the ;reck, or z e n a n a af Lhc }'ca.-.
Figure 3-2.2.2(a)
Separation
distance, R.
3-2,5,1 T h e selected desi_~a fire size s h o u l d r e p r e s e n t a credible
worst case scenario. Desigmers a n d analysts are strongly c a u t i o n e d
~gainst selecting m o d e s t fire sizes based solely on the type or
limited a m o u n t of combustibles that are p r e s e n t or e x p e c t e d .
3-2.5.2 In low ceiling spaces (ceiling h e i g h t less t h a n 25 ft) where
sprinklers are provided, t h e design fire consists either of a steady
design fire or a fire that grows to s o m e steady t h r e s h o l d size. for
example, d u e to o p e r a t i o n of a n a u t o m a t i c s u p p r e s s i o n system.
\
< ' - -
:;
3-2.5.3 In h i g h ceiling spaces (ceiling h e i g h t at least 25 ft) where
Fuel
items
/
.........
[
a n d Sprinkler A c t u a t i o n .
3-3
Figure 3-2.2.2(b)
Fuel
items.
3-2.2.3 Design Fire Size. Specification of a fixed desigt~:*.:~ :+":+;~+++
"e s i~.'..~
applicable to all situations is n o t realistic. T h e type ~
nou . ~ o f
fuel s h o u l d be considered when d e t e r m i n i n g the c l e s ' l ~ " ;!:" +¢s ~ i
Further, a s t a n d a r d size design fire c a n n o t be r e c o m m e n ~ ~.~. u e t'~
the lack of available data in North A m e r i c a to i ~ . . q
tha +~+++-+.
design fire is only e x c e e d e d in a limited pro.:~+."P~h+6"fi~ .+ ~i~.+-+,.+++
i n c l u d i n g either atria or covered malls.
.:..:~. . . . .
+;-'~%
"T.-m"
++.:++-.+':'.':~,..
~ '~i
•
3-2.3 U n s t e a d y Fires. An u n s t e a d y fire ++ ~ . . a t
varies:~ ith
respect to time. A t-squared profile is often ~ . e d
for.$ 6steady
fires. T h e n , t h e h e a t release rate at a n y time is ~ ' ~ b~..-'$+Pquation
(2):
Q = lO00 (t/t~) ~
(2)
where:
Q = h e a t release rate f r o m fire ( B t u / s e c )
t = time after effective ignition (see)
tg = .growth time (see)
g = u m e interval f r o m t h e time of effective ignition until the fire
exceeds 1000 Btu/sec.
can be estimated f r o m t h e t e m p e r a t u r e rise g e n e l ~ e ~ by t~¢ fire at
those locations. T b e t e m p e r a t u r e rise d e p e n d s o n t h e vertical
distance above t h e base of t h e fire a n d t h e radius f r o m t h e fire
centerline axis. NFPA 72. National Fire Alarm Code. provides a
p r o c e d u r e for d e t e r m i n i n g h e a t detector s p a c i n g (for h e i g h t s less
t h a n $0 ft) based o n t h e size a n d growth rate of t h e fire to be
detected, various ceiling heights, a n d a m b i e n t t e m p e r a t u r e s . T h e
u n d e r l y i n g theories, a s s u m p t i o n s , limitations, a n d k n o w n a n d
potential sources of errors for estimating t h e r e s p o n s e time of
s m o k e a n d h e a t detectors are identified a n d discussed in ISchifiliti
& Puccil. An e n ~ n e e r i n g analysis is n e e d e d for ceiling heights
greater t h a n ~0 ft.
See A p p e n d i x C for f u r t h e r i n f o r m a t i o n o n t-squared profile fires.
D u e to the dynamics of s e c o n d a r y ignitions, a t-squared profile
can be u s e d for e n g i n e e r i n g p u r p o s e s until large areas b e c o m e
involved. T h u s , a t-squared profile is reasonable u p until the fire
growth is+limited either by fire control activities or a sufficient
separation distance to n e i g h b o r i n g combustibles to p r e v e n t f u r t h e r
ignition. After this dine, it is a s s u m e d that t h e fire does n o t
increase in size.
fr+m c+..'~..=+n Pads +~mt ::'+'-!J c~u:c dctcc+-+n ~)" a rca=+nm~!7
~°°-+:+;'- . . . . ,+. . . . . . . : . . . . . . .
+~-~.-.
: . . . . ,., o n o ~ ~. . . . . .
: . . . . h, -+-,ln°+'~.
3-2.4 Data Sources for H e a t Release Rate.
?Jlo;'An~ e^- +&crm~2 lingand can~'-cd':c
+P" . . . . . . . . . . . . .
~ o q*
f'^:t:--
.....
3-2.4.1 Recendy, a limited a m o u n t of h e a t release rate data for
s o m e fuel c o m m o d i t i e s have b e e n r e p o r t e d [2,3]. (See Appendix
B.) However, f u r n i t u r e construction details a n d materials are
known to substantially influence t h e peak h e a t release rate, s u c h
that h e a t release rate data are n o t available for all furniture items
n o r for "generic" f u r n i t u r e items.
.~+;
• h~
~ +
.~4./~/+o~
624
L" .
.
. . . . . . . . . .
+k . . . .
. . . . . . .
+. . . . . .
/cj
.
+.+~+
A..-+:
.
~ . . . . . .
1
~'I:" ............
P.r . . . . . .
11
+. . . . . .
.
.
"
.z c ' : _ ^ . a
.
.
, ~ A + +
A
.
l
"
x+l"t"
.
.
.
.
............
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r~._^.~__.+__.v..
Nca=
.
la.~,
~3Jithn o
+r... . . . . . . . . .
.
•
IF" . . . . . . .
/ D T I \
. . . . . .
I^.:+.
rol
. . . .
++.
-P. . . . . . . . .
I" . . . . . . . . . . . . . . . . . . . . . . . . .
~-l-{-~.]_.p_~.c_-l-~-J_
~+
T ..........
A
~*~I
. . . . . . . .
.~-+~I.I+-L" + ' ` ' u ~ ' +
+~+:
:^
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. . . . .
1 o
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I. . . .
C
NFPA 92B -- MAY 2000 ROP
. . . . . . . . . . . . . . . . . . . . . .
~++ . . . . . . . . . . .
I ~ ^ - - ~ + :
. . . . . .
L'IY . . . . . . . . . .
+ .....
+ +I ........
,.:'~1^~1
:
T ^ k l +
" . . . .
Q m O
.........
at
O ~
+ . . . . . . . . . .
1
k+.^,-I
O
=. . . . . . . . .
. . . . .
:~1.1----
~
t. . . . . v . . . . .
~"
:^_
t~e :'ezt=!zficn
..(<2
......
, ............................
c h a n g e 7-ar
t a x "z m c z : : c c u r z t c "~? , / H 2 £ 7.!, t £ A=°O : : c = : d
r o t e d ~ . e : = a t e r = e c c d 1 . 0 a i r ch-~--':gc ~ c r h a u r .
3-4_* Stratification o f Smoke•
t ~ j . . . . . . . . . .
k~+
.....
~
*I-.+
I:" + • + . . . . .
---. . . . . . . . . . . . . . .
~ .
+. . . . .
. . . . . . .
A +I++. . . . .
~rr ...........
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,
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7 ....
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+.,..+
th
. . . . . . . .
+. . . . .
...........
t" . . . . . . .
. . . . . . . . . . . .
+.,,=~.,++~.+
= ~,
,
.
~I.I=.
.eg
*. . . . .
.........
"~"
+:~--
•=-•o
</ A
+I~-
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . .
++,
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.
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. . . .
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e l ^ ^ _ ,
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.
.
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.
.
.
.
r111
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+. . . . .
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............
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g ...........
,,. . . . . -7~+' . . . . • . . . . , ~ t " . . . . . .
c ~ r l 7 a f t e r :g==lt=Cn, d e p e = d : z g
c: ~c :c==;'cct:;'c ~eat :clcz~c rztc
e+-=d xt-.c m - = = ~ ' c = : t e m p c ~ v - r c
~'aN=+.2c= " = ~ e c p c = s p = c e . +'12".'=
x , , ~ + + + , ~
+.,+,~+.+++++
I
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+
r , l ,
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.
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mtc
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1"~'^":+'1^"3
~P+kl ^
;_
~ 9 C) O
¢1+
~I,I^-
Delete existing equation (5)
".LL:2::y:LL^L:?~:':.:+7..::.3 :::" ": : - : T Z : . . : : L +LU::."%~ . . . . . .
r ~
T~.
. . . .
t+'~ . . . . . . . . . . . . .
.-I
:_
+~,.,
+i~^
. . . .
u.+t"^
d]ffc:.e~ce
.ram_=. . . . . . . . . . . . . . . .
. . . . . . . .
A '-It'/.a.
I-.+1+1-,+ I
13,. . . .
to1
I. . . . . .
.
:~.,I:~..+^+.I
:
+I~
+~l,.li~
I:
--.
: ~ + ^ ~ ^ I . + ' . . ~
o
~
~, . . . . . . . . . . . . . . . . . . . . . . . . . .
+1 . . . . . .
~ + ^
+C
, . : ~
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~+P +1..-
^C
I-.^^+
~I~.:_--+
,'+f=~ ,,.~,
~I . . . .
+. . . . .
+~
.
IU+..
.....
.:÷1+.
/.^.~
. . . . .
~
+~
o]~ lC+X
.^_
b e u = c d . The z . = c s c ! a t e d t i m e f o r a c t u = f i c = ,
.~ c . z ~ b e e = f i m a t e ~
~}"
,,.:--~+,..+~v ~. . ~. . . . : ^. ~. . (~.),
. . . "'"'+'.
.
++'~.~ t e m p e ~ t u r e
r~zc being t . h c a e t e . . - - . . ' n c d
arn~'cnt
_
. . . . . . . . . . .
?"'+
L" . . . . . . . . . . . . . . . . .
+ . . . . . . . .
)
tempe:'ature.
+T'I+.^
+. . . . .
~ . . . .
+7+1-.
. . . .
I. . . . .
+I+.^
A ~
~^:1:
. . . . .
I~^
L:;+_:::~ ~:':~:':::C~: ~+'L:::::5 .r:'~+~ 7==a-;';'~,~', +-+++_.
thc =mc!.c !a.)'zr dec= n a +. a a - a t i f / p r c m = = u r c ;
+t ,+ , ~.__*._: m ~ _
. . . . . . .
:~+^1..
~?. . . .
~
+t".t+f. . . . . . . . . . .
!
.-1:. . . . . . .
7 (;oo
:':--e, +'^:-~'" --+:-"
+...1":.=.:]
'~"
+I~^
~ . . . . .
. ....
-+,=.^C .1,. . . . .
I ....
. . . . . . . .
V . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ICI
+" +'
4).
Sc=~=r+ #
.:+L"
t!~.C
In
d a t a + F c r X £ !"+0:
Delete existing equation ( 3 )
v
....
=+0_..i,]
~/~
~
=d
Delete existing equation (7)
...t.:~+. ~ _ , . . . . .
r .....
i. , - ~ ~ _ _ . . . r^. n .-:". . . . rs-v
Z:Z"..:.Y27+:.2: ~ L 7 2 ~ : ~ - - - - ; b L S " ~ . . . . . . . . . . .
~ ......
+* .....
Delete existing equation (8)
tend: t e e : ' e r ~ S m a t e
.....
•k
.+ . . . . . . . . . . . . .
+:~--
. . . . . .
A.Ig + 1
+=
£~ ~ A
=,+
~ = ~
/7 ~X
,-+1
1
:+A:.--+
.u
. . . .
+1....+
...........
:. . . .
. . . .
. . . . . .
v=
k: ....
~"^
"•'~
~
+,.I~.--
"
•A
+. . . . . .
.........
I U Q
+.1.+.
--:~"*
A
P+-^.
r
.
.
.
'+'^ c c . n ~ ! d e r c d
'.^^
p*...+:^.
+k--~
O f oarticular interest are those situations w h e r e the temperatur c
of the air in the uDDer n o r t i o n o f the large o p e n snace is ~reater
than at lower level's'before t h e fire. This-can occur as a re-suit of p,
solar load where the ceiling contains glazing materials.
Comoutational_ m e t h o d s a r , i+vallable to assess the potential for
intermediate stratification.
~ . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . .
k . . . .
,~ _Jl~ . . . . .
.
:--
"~
l
; ...........
+. + . . . . . . .
. . . . . . . . .
+~
he+K--.
~, . . . . . . . . . . . . . . .
IPt.--.
o.
:J----E,..
"1 . . . . . .
t +~1
++J
--:+k+
I.. ....
t--:+:~ll.,
c ...~+
I:[ 1 T - - ^ + ~ . r i . .
...,.~-.,=+o
2-~+_+^ . . . . . . . . . . . . .
...k.l'l~
C'JI~'$ <:/1 I
. . . . . . . . . . . . . . . . .
r ~ . ~`+. , " . . . . . . .
• "~+'~
lf'lt~t
*,5mez.
r+~e a t = d e - - n e e d
+:, . . . . . . . . . . . . . . . . . . .
f l ira, I ' P ~ . +
IY . . . . . . . . .
I:--,,:A
~--+,.
9t 0
+~e temFcrat'are
$-4.1 General. T h e uotential for swatification relates to the
difference in temperature between the s m o k e and s p r r o u n d i n g aiF
at any elevation [111. T h e m a x i m u m h e i g h t to whk;h p l u m e fluid
(smoke~ wiU rise. esneciallv early after imaitlon, d e u e n d s o n the
convective heat release rate a n d t h e a m b i e n t temperature v'triatlen
in the o p e n space.
~" ....
. . . . . . . . . . . . . . . .
b
.:^~
~
.....
. . . . . . .
+--,dl
.
.
.
t +" . . . . . .
"st,~ty 10~. 1
O n e case of interest is denicted in Figure 3-4. In this case. the
temoerature of the a m b i e n t air is relalively constan t UP to a h e i g h t
above which there is a laver o f warm air at u n i f o r m temperature.
This situation can occur if the u p p e r portioq of a mall. a l r i u m , o r
other large space is unoccutfied so that the air in that portion is left
unconditioned.
+k~
J . . . . . . . . . . . . . . . . . .
e;+Smatcd ~ a f'd=ctla~ cf "Zinc ~ed
~ n +&care+-c~M g e n c . - a l i z a + . 2 c : :
cf ~he limited amaunt
af expcrlmen+.at
data:
T'++~
~++:~o+
: .....
+:~+t
. . . . .
~+I . . . . . . .
+~) . . . . . . . . . . . .
,:+k
~..++~+:
, . , + ~ . ~ I
1" ...........
A~+~
~
*h
. . . . . . .
..,,:++I..
+
I:--:+^A
. . . .
T~,.+~.+++~I
+^:l:~+
. . . . . . . . . . . . . . . . . . . . . .
=~
3-4.2 Sten Function T e m o e r a t u r e . Where the interior air has a
discrete temperature c h a ~ e at s o m e elevation above floor level,
t h e n the ootential for stratification can be as+essed by applying th e
o l u m e centerline t e m n e r a t u r e correlation, Where the o l u m e
+ + : I t + +
F11+'11
t = +J,
...h+.~
.....
, +
625
NFPA 92B ~
MAY 2000 ROP
Q = heat release rate of fire (Btu/sec)
Q, = c o n v e c t i v e p o r t i o n o f h e a t r e l e a s e r a t e ( B t u / s e c )
q e n t e r l i n e t e m p e r a t u r e is e o u a l t o t h e a m b i e n t t e m p e r a t u r e , t h e
n l u m e is n o l o n g e r b u o y a n t , l o s e s its a b i l i t y t o r i s e , - a n d s t r a t i f i e s a t
t h a t heittht.
3-4.3
Imnact
of Stratification
of Smoke
on Smoke
Q , = J" (1 - ~ ) Q d t f o r s t e a d y fires: Q n
Management
= (1 - ~ t ) Q t ( B t u ) f o r t ~ fire
Q n = ( 1 - g , ) (/,t~/S ( B t u )
S y s t e m I ) e s k r n . O n c e a s m o k e e v a c u a t i o n s v s t e m h a s s t a r t e d in a n
a t r i u m 91" 9 t ~ e r l a r g e s n a c e , t h e s t r a t i f i c a t i o n c o n d i t i o n will b e
e l i m i n a t e d b y t h e r e m o v a l o f t h e h o t laver. T h e p r o b l e m f a c i n ~ t h e
d e s i g n e r is h o w t o e n s u r e t h a t t h e n r e s e n c e o f s m o k e is n r o m p t l v
d e t f e t e d t h r o u g h all o o t e n t i a l p r e - f i r e t e m n e r a t u r e p r o f i l e s . U n d e r
s g m e c o n d i t i o n s , suc[a as n i g h t s a n d c o l d days. it i s ~ o r o b a b l e t h a t a
~ t r ~ t i f i c a t l o n c o n d i t i o n will n o t b e p r e s e n t a n d a n y s m o k e n l u m e
will p r o m n d v rise t o t h e r o o f o r c e i l i n ~ o f t h e v o l u m e , in w h i c h
case detection at or near the top of the volume would be
r e s p e n s i v e . I n o t h e r cases, s u c h as h o t s u m m e r d a y s o r d a y s w i t h a
h i g h ~olar l o a d . t h e n l u m e m a y n o t r e a c h t h e t o p o f t h e v o l u m e
a n d t h e s m o k e c a n s o r e a d a t a level l o w e r t h a n i n t e n d e d , in w h i c h
case d e t e c t i o n n e a r t h e tot) o f t h e v o l u m e w o u l d n o t r e s o o n d a n d
t h e s r a o k ¢ m a n a g e m e n t s v s t e m w o u l d n o t b e s t a r t e d . Tl~ere is n o
s u r e w a y o f id¢Bt~fying w h a t c o n d i t i o n will b e p r e s e n t a t t h e s t a r t o f
a fire. T h e f o l l o w i n ~ a r e t w o d e t e c t i o n s c h e m e s t h a t c a n o r o v i d e
for prompt detection re~ardless of the condition present at the
time of fire initiation.
Q,= po ct To A ( H - z ) ( B t u )
t = t i m e f r o m i g n i t i o n (see)
Tx= a b s o l u t e a m b i e n t t e m n e r a t u r e (R)
A T = t e m p e r a t u r e rise i n s m o k e l a y e r (°F)
V= v o l u m e t r i c v e n t i n g r a t e ( f t S / m i n )
Yi= m a s s f r a c t i o n o f s p e c i e s i (Ib s p e c i e s i/lb o f s m o k e )
z = h e i g h t f r o m t o p o f f u e l to s m o k e l a y e r i n t e r f a c e (ft)
0 [ = t~ f i r e g r o w t h c o e f f i c i e n t ( B t u / s e c s)
p o = d e n s i t y o f a m b i e n t a i r ( l b / f t s)
~0~=
~
c o m b u s t i o n e f f i c i e n c y f a c t o r (-), m a x i m u m
v a l u e o f 1 [21]
= t o t a l h e a t loss f a c t o r f r o m s m o k e l a y e r t o a t r i u m b o u n d a r i e s ,
maximum
v a l u e o f 1, m a x i m u m
temperature
rise will o c c u r if ~
=0
(a~ BeamDetection of the Smoke La~er at Various Levels. T h e
~ m . ~ i. . . . . : _ . ~ ^ _ ~ ' f - ~ _ , t. . . . . . . . . . : . . . . .
,.^ c. . . .
L.. . . .
,.^
p u r p o s e o f t h i s a p p r o a c h is t o uuici~lv d e t e c t t h e d e v e l o p m e n t o f a
, . . . . . : . . . . . . . ~ ' ~ ' ~ . . . . :^ o~: . . . . .
I- . . . . I. . . . . . . . . . . . . . . . .
:^~
- a ¢
~^a:~:~_^
~c.^_ : . . :_:.:~, . . . . . . : ^ _ . , . ^ . ^ :. . . . .
,.^
s m o k e l a v e r a t w h a t e v e r t e m p e r a t u r e c o n d i t i o n exists. O n e o r
an~ tor a ~
~:.,, ...............
v ....... , ...............
fill:....
. . ~,
. . .~x.-,x.~.~'~
.
.;::':*.^ ..~..;~"-':,~.;$~...t.:~L.
m o r e b e a m d e t e c t o r s a r e l o c a t e d a t t h e r o o f level. A d d i t i o n a l
. . . r~-:~ . . . . . . . .,t.
. . ......... . . . .b^ ]. . ~. .. .. . . :-,^..¢^~^
. . . . . . . . . . . . . .I......... .I . . . . .~ :~
d e t e. c t o r s . a r e .l o c a t e. d a t .o t h e r . levels
lower in the volume The exact
. . . . . -::~.. - - t ~ : , ~ . . . . . . . . . ~:~.-..~
.........................
:~-.
.
~:,:<~.,
p 0 s m o m n g o f t h e b e a m s ts a f u n c t m n o f t h e s n e c t f i c d e m g n b u t
_,~::'...:.: . . . . .
~v" .
. o
- •
•
e
-....
; .
.
.
.
.
.
.
- ....
~krmtl~.~
o t r~rst l n ~ l c a t m n
ot amoge :~7c..=tot.ace
at A n y
S~QUI(1 i n c l u o e p e a m s a t t h e o o t t o m o t a n l a e n n n e o
-/~.':2&.
"~:.'::::::,
"
~]~1~:-'..
..':::~::::~
u n c o n d i t i o n e d s p a c e s a n d a t o r n e a r t h e d e s i g n s m o k e level w i t h
~-.-~::' "-'::"
s e v e r a l it) t e r m e d ] a t e b e a m p o s i t i o n s a t o t h e r levels.
.-.
$-6.1 " ~ . . . a l . ~ .,.The p o s i t i o n o f t h e f i r s t i n d i c a t i o n o f s m o k e
":,.'.:'~?:~..~.:...i n t e f f - a e e - ~ i ~ i ~ : " t i m e c a n b e d e t e r m i n e d f r o m t h e r e l a t i o n s in 3-6.2
(b) //corn Detection of the Smoke Plume. T h e p u r p o s e o f t h i s
"~.:..S.ectlo~ii'~7.
The relations address the following three
a p n r o a c h is t o d e t e c t t h e r i s i n g ~ l u m e r a t h e r t h a n t h e s m o k e laver.
~:.:"~. " ~ i : . "
For this approach, an arrangement of beams close enough to each
:'% ..::#'
~....................
...'.:.' .~ i~
o t h e r to e n s u r e i n t e r s e c t i o n o f t h e n l u m e a r e i n s t a l l e d at~'~':..:'!~,:
"~ilIi!:" (1) gNo s m o k e e x h a u s t is o p e r a t i n g (see 3-6.2)
b e l o w t h e l o w e s t e x p e c t e d s t r a t i f i c a t i o n level. T h e s p a C ~ b e i ~ !
":-:.~, .(~) T h e m a s s r a t e o f s m o k e e x h a u s t e q u a l s t h e m a s s r a t e o f
. . . . . . . .
. . . .
~ .,:z::::,....-¢ .
:~oke
s u p p l i e d f r o m t h e p l u m e to t h e s m o k e l a y e r (see 3-7 I)
oasecl o n m e WlCim -o .I m. e .p e .a m. a t. tile
least elevarlorr:iat~/e a D~E~,
~?....!::., ~ , ~ _
,
,
,
. ,
.,
.,
~
•
:"" ":::.':~:::, Z-.':-"'-":':::::i::%::,.
":ik¢: L31 l n e m a s s r a t e o i s m o k e e x n a u s t is less t i t a n m e r a t e o r s m o k e
o f f i r e p- o t e n t t a l "
~i~
":"::ii~ii~
i: s u p p l i e d f r o m t h e p l u m e to t h e s m o k e l a y e r (see 3-7.2)
•
u . . . . .~. . . . r , ^ ~ : : .
":::::.'::",
S m o k e L a v. e r P r o n-e r t ~ e s " . . . . . . . . .
~:..~'"'~~-:;~'
y .......
~. . . . . . .
7 ~': .....
7 . . . . -~. ~ .'7.-.'~'" ~.. . . . . ~'~;.~..:.'.-:::'
3 "5
,
$-6.2 ] J ~ h . [
(e.g., C O , H C ! , H C N ) " : : :..~.c!:e ]:)'er::':" E " ~ : o n s
to ~late
the
s m o k e l a y e r d e p t h , a v e r a g e t e m p e r a t u r e rise, ~ . . a l
den~,
and
s p e c i e s c o n c e n t r a t i o n s d u r i n g t h e s m o k e f i l l i n g ~ . . ¢ . , a..~.""t h e q u a s i s t e a d y v e n t e d s t a g e a r e p r o v i d e d in T a b l e 3-5. T h ~ i ~ h a t i o n s
apply for fires with constant heat release rates and~uared
fires.
These equations can also be used to calculate the i!onditions
w i t h i n t h e s m o k e l a y e r o n c e t h e v e n t e d c o n d i t i o n s exist.
Table
$-5
Equations
e--^~Parameters
Steady
Fires
Exhaust
Operatmg.
3-6.2.1 S t e a d y F i r e s . F o r s t e a d y fires, t h e h e i g h t o f t h e initial
i n d i c a t i o n s o f s m o k e a b o v e t h e f i r e s u r f a c e , z, c a n h e e s t i m a t e d f o r
a n y t i m e , t, f r o m E q u a t i o n ( 0 2 3 , w h e r e c a l c u l a t i o n s y i e l d i n g z/H >
1.0 m e a n t h a t t h e s m o k e l a y e r h a s n o t y e t b e g u n t o d e s c e n d .
z/H = 0 . 0 7 - 0 . 2 8 In [( t(~/S/l-r/3)/(A/It 2) ]
for Calculating
re.n:__ S~c
•
.x
] g e s i t o - ~ o f F i r s t I n d i c a t i o n o f S m o k e •: ~ ) ' c : .---tc..:.cc
w~th N o S m o k e
Unvented
Properties
of Smoke
Layer
Fires
T-squared
Fires
Vented
Fires
AT
. T ~ [ e x p ( Q . / Q o ) ] - 11
_T~[exp ( Q o / Q ) I - l i
[00(1.Z, ) Q~/(pocpF)
D
(D,Qt)/[ZoAHe4(H.z) ]
(D=a t~)/ [$c, DH,A(H-z)]
(60D,,Q)/(Z~AH, V)
E
~ Q t ) / [ OoXoAH,A(H-z)]
~oe d)/13Oox.AH, A(H-z)]
(60fQ)/(poZ~AHy)
where:
A = h o r i z o n t a l c r o s s - s e c t i o n a l a r e a o f s p a c e (ft ~)
c, = s o e c i f i c h e a t o f a m b i e n t a i r ( B t u / l b * ° F )
/5 = L - ~ l o g ( l J / ) , o p t i c a l d e n s i t y
D~ DV/m/, = m a s s o p t i c a l d e n s i t y (ft 2 / I b ) m e a s u r e d in a t e s t
s t r e a m c o n t a i n i n g all t h e s m o k e f r o m a m a t e r i a l t e s t s a m p l e
V = v o l u m e t r i c f l o w r a t e (ft 3 / s e c )
L
f = y i e l d f a c t o r o f s p e c i e s i r i b s p e c i e s i/lb f u e l )
H = c e i l i n g h e i g h t (ft)
AH~ = h e a t o f c o m p l e t e c o m b u s t i o n ( B t u / l b )
(023
where:
z = h e i g h t o f t h e f i r s t i n d i c a t i o n o f s m o k e a b o v e t h e fire s u r f a c e
(ft)
H = c e i l i n g h e i g h t a b o v e t h e f i r e s u r f a c e (ft)
t = t i m e (see)
Q = heat release rate from steady fire (Btu/sec)
In = n a t u r a l l o g
A = c r o s s - s e c t i o n a l a r e a o f t h e s p a c e b e i n g f i l l e d w i t h s m o k e (ft 2)
626
NFPA 92B -- MAY 2000 ROP
E q u a d o n (0_33 is based on e x p e r i m e n t a l data f r o m investigations
u s i n g u n i f o r m cross-sectional areas with respect to h e i g h t with
A / H z ratios in t h e r a n g e f r o m 0.9 to 14 a n d for values of z/H>_ 0.2
[7, 10, 12, 13, 14]. This e q u a t i o n is for t h e worst case condition, a
fire away f r o m any walls. T h e equation provides a conservative
estimate of hazard because z relates to t h e h e i g h t where t h e r e is a
first indication of smoke, rather t h a n t h e s m o k e layer interface
position.
where:
m = total fuel m a s s c o n s u m e d (Ib)
At = d u r a t i o n of fire (sec)
H, = h e a t o f c o m b u s t i o n of fuel ( B t u / l b )
tg = growth time (sec)
3-6.2.4* Varying Cross-Sectional Geometries a n d C o m p l e x
Geometries. Equations (07) and (~08.) are based o n e x p e r i m e n t s
c o n d u c t e d in u n i f o r m cross-sectional areas. In practice, it is
recognized that spaces being evaluated will n o t always exhibit a
simple u n i f o r m geometry. T h e d e s c e n t o f t h e first indication o f ~
s m o k e layer- in varying cross sections or c o m p l e x g e o m e t r i c spaces
can be affected by conditions s u c h as sloped ceilings, variations in
cross-sectional areas of t h e space, a n d projections into t h e rising
p l u m e . W h e r e s u c h irregularities occur, o t h e r m e t h o d s of analysis
s h o u l d be considered. O t h e r m e t h o d s of analysis, which vary in
their complexity b u t m a y be useful in dealing with c o m p l e x a n d
n o n u n i f o r m geometries, are as follows:
3-6.2.2* U n s t e a d y Fires. "I~e d e s c e n t of t h e h e i g h t of t h e initial
indications of s m o k e can also be estimated for certain types o f
u n s t e a d y fires, for example, t-squared fires. F r o m basic theory a n d
limited e x p e r i m e n t a l evidence, the h e i g h t of t h e initial indications
of t h e s m o k e above t h e fire surface, z, can be estimated for a given
time a c c o r d i n g to t h e following relation, where calculations
yielding z/H > 1.0 m e a n that t h e s m o k e layer has n o t yet b e g u n to
descend.
z/H = 0.23 [ t/( tg~/s Pi4/~ (A/H2) s/s) ]-i.4s
0"0_43
(a) Scale m o d e l s (see 3-1.1 and 3-1.2).
(b) CFD -~-¢¢4dm o d e l s (see 3-1.1).
(c) Z o n e m o d e l adaptation. A zone m o d e l (see 3-1.1.3,1)
(ft)
predicated on s m o k e filling a u n i f o r m cross-sectional g e o m e t r y is
H = ceiling h e i g h t above the fire surface (ft)
modified to recognize t h e c h a n g i n g cross-sectional areas o f a space
t = time (sec)
(see 3-1.1). T h e e n t r a i n m e n t source can be m o d i f i e d to a c c o u n t
tg= growth time (sec)
for e x p e c t e d increases or decreases in e n t r a i n m e n t d u e to
geome'tric c o n s i ~ s ,
s u c h as projections.
Equation 0 - 0 4 ) is based on e x p e r i m e n t a l data f r o m investigations
(d) S e n s i t i ~ t . ' n a l y s ' ~ " An irregular space is evaluated u s i n g
with A/H2 ratios in the range from l.O to 23 and for vaiues of z/ H>_
Equations ( ~ f f ~ , ( i O _ 8 . ) at a n d between the limits of a
0.2 [10]. Equation (J,O4) is based on u n i f o r m cross-sectional areas
maximum ~ght'~:minimum
h e i g h t identifiable from t h e
with respect to height. This equation is for t h e worst case
g e o m e ~ i ~ : ~ . e s p a i ~ ' ~ n g . e q u i v a l e n t h e i g h t or volume
condition, a fire away from any walls. T h e e q u a t i o n also provides a
cons~'~'$'~Z
":~'-"
conservative estimate of hazard because z relates to the h e i g h t
.-.-::':'.-::';" :.:,
~'i'i~:"
where there is a first indication of smoke, rather t h a n the s m o k e
...~.:~.~ P ~ o n
of Smt~'e Layer Interface with Smoke Exhaust
layer interface position.
"()p~:':::::iii'~:.
"'::'~:::~::.:..
3-6.2.3 Mass C o n s u m p t i o n . T h e equations p r e s e n t e d in 3-6.2.1
~.
3-7 6 , g . ~
. ~ t e o f S m o k e E x h a u s t Equals Mass Rate o f Smoke
~nde3~te2r2i a r e t i u ? ! ~ l o i ? : s ~ a e l U c ~ v f i ~ g e , t h t e h P t S l t ~ l ° ~ ~ Y
"~;.~:.u..~llied~r
the s m o k e exhaus.ts.ystem h .as.operated for a
s,,
•
z
v
:~: . : ~ e n t
.1~,¢1oa ot u m e , a n e q u m n n u m p o s m o n ot m e s m o k e
re.c[uired to sustain t h e steady h e a t release rate over t h e time period "?"ii!-, ~ a c e
will be achieved if t h e mass rate of s m o k e e x h a u s t is
of interest can be d e t e r r a l n e d as follows :
~!~g::..'-'~ou
~ u a l l ~ " t h e mass rat e o f s m o k e suDplied by t h e p l u m e to t h e base
........
.,:.i~#~-~
"?-{$ior* t h d ' s m o k e layer. O n c e achieved, this position s h o u l d be
m= QAt/H~
as long as t h e mass rates r e m a i n equal. See Section 3.$.:~..:.y,
:::::::. (~lg.~
.:.#.
. ~,'..-,W~tintained
,::;
.~.:-:.:.:-:-:-:..
:--:......
~.,.
i~.~ for t h e .mass rate of s m o k e s u P P h. e d to t h e base of t h e s m o k e
.
:i::"".'
.
'
:i:i..'
~--.,
.:.::~:~)~'.':-.~.
'~.~
where •
,
•
"!.'.'~.~;::" " ' : ~
layer for different p l u m e configurauons.
m = total fuel mass consumect (lb)
"~i:~--:,$:.,,
"-':'-'.".-':'.-'.".~
Q = h e a t release rate ( B t u / s e c )
..*:-'?.:.'~ii~i~:--"~:::.-.., ":~i-:.-"~
......
3-7 6 ~ . 2 Mass Rate o f Smoke Exhaust Not Equal to Mass Rate of
At = d u r a t i o n of fire (sec)
":~:."-!:."-~::.:-'
- o k e Suoolied.
•
•
..:,.~':~" " ":-"~::-.
.~.:.:.:.:.:.:..
-.~x.:.w .:'¢"
Sm
With a vreater rate of mass sunt~lv t h a n exhaust,
H, = h e a t of c o m b u s t i o n of fuel ( B t u / l ~
":;~i?:. .--:f;':
an equilibrium position o~ t h e s m o k e layer interface will n o t be
¢~'~"::~;~':.~,
. ':~.i~":.
achieved. T h e s m o k e layer interface can be expected to descend,
vor a• t-s,q u n f e d fire, t h e" total mass .consum""
tlae t'ti~e
• n o e x h a u s t was provided
~ : .~.ver
.,
~.~
t h o u g h at a slower rate t h a n ff
(see 3-6.2),
eriod
ot
interest
can
be
deterrmnect
as"
"
'
~
~
P
•
%!:...'..~..-., :.#
Table~ g4Gg-,$.~:.7~ include~ i n f o r m a t i o n o n t h e- s m o k e layer
. . . . ~ . . . . . ~,
":":'~i.:'."-'~'i....
'":
, ....
position as a f u n c t i o n of time for axisymmetric p l u m e s o f steady
m = ~ a r / t tx,~g )
~i~i;"
K~-~-q~
fires given the inequality of t h e mass rates. For o t h e r p l u m e
4::
configurations, a c o m p u t e r analysis is required.
where:
z = h e i g h t of t h e first indication of s m o k e above the fire surface
Table 3-7.2 Increase in Time for Smoke Layer Interface to Reach Selected Position
(Axisymmetrlc Plumes and Steady Fires)
t/t o
m/m r =
0.85
0.93
1.55
1.89
2.49
1.63
2.05
2.78
1.72
2.24
3.15
1.84
2.48
3.57
1.52
2.00
2.78
4.11
1.61
2.20
3.17
4.98
1.71
2.46
3.71
6.25
0.25
0.35
0.5
0.2
1.12
1.19
1.3
0.3
1.14
1.21
1.35
0.4
1.16
1.24
1.4
0.5
1.17
1.28
1.45
0.6
1.20
1.32
0.7
1.23
1.36
0.8
1.26
1.41
0.7
z/H
627
NFPA 92B -- MAY 2000 ROP
T h e p l u m e mass flow rate, m, above the limiting elevation is
predicted from:
where:
z = design height of smoke layer interface above fire source
H = ceiling height above fire source
t = time for smoke layer interface to d e s c e n d to z
to = value o f t in absence of smoke exhaust [see Equation (9)]
m = mass flow rate of smoke exhaust (minus any mass flow rate
into smoke layer from sources other than the plume)
rn, = value of m required to maintain smoke layer interface
indefinitely at z [see Equation (14)]
m= 0.022 QcllSzJlS+ 0.0042 Q, (z > zt)
where:
m = mass flow rate in plume at height z (lb/sec)
z = height above the fuel (ft)
(t-4~
The plume mass flow rate below the flame tip is predicted from:
m=0.0208 Q?l~z (z<_ zt)
$ . ~ t Rate o f Smoke Mass Production. The height of the smoke
layer interface can be maintained at a constant level by exhausting
the same mass flow rate from the layer as is supplied by the plume.
The rate of mass supplied by the plume will d e p e n d on the
configuration of the smoke plume. T h r e e smoke plume
configurations are addressed in this guide. The exhaust fan inlets
should be sized and distributed in the space to be exhausted to
minimize the likelihood of air beneath the smoke layer from being
drawn through the layer, sometimes referred to as phtggi-ng
plugholin~. To accomplish this, the velocity of the exhaust inlet
should n o t exceed a value to cause fresh air to be drawn into the
smoke layer.
(t-59.)
3-~-.1.3 T h e rate of mass supplied by the plume to the smoke
layer is obtained from Equation (-t69.) for clear heights less than
the flame height [see Equation (-l-g3] a n d otherwise from
Equation (t-48). The clear height is selected as the design height
o f the smoke layer interface above the fire source.
8-~g.1.4 It should be n o t e d that Equations (-1-4.8.) and (t-g~) do
n o t explicitly address the types of materials involved in the fire,
other than through the rate of heat release. This is due to the mass
rate of air entrained being much greater than the mass rate of
combustion products generated a n d due to the a m o u n t of air
entrained only being a function of the strength, that is, rate of heat
release, of the fire...:..
3 ~ g . l Axisymmetric Plumes• An axisymmetric plume (see Figure
-g-g--/-~.-.~-d) is expected for a fire originating on the atrium floor,
removed from any walls. In this case, air is entrained from all sides
a n d along the entire height of the p l u m e until the plume becomes
s u b m e r g e d in the smoke layer.
- ........
....
v............
v . . . . . . ~, . . . . . . . . . .
v .........
. .... ~'¢~2 ~•.L~wE~^-.:.. ^c . _ ^ , . ^ .
D el ~ x ! ~ s h~ g e q u a t i o ~ l ~ ' ~
H
)
\
\
[
I
I Z.
I
I
I
I
I
]
I
/
~'~'..~l~,g.l.5 6 ~
can be located near the edge or a corner of the
~.~'~"
.~ In this case, e n t r a i n m e n t might n o t be from all sides
'~":':~:
.~
~x : ~ ". . . C::;::::~¥'k
• •
,~ ,~i~i.fi'~,~me, resulting m a lesser smoke productaon rate than
~-..~:
"~Wh~'ntrainment
can occur from all sides. Thus, conservative
.::#'-*:" ' ~."::~,
~ d e s i g n calculations should be c o n d u c t e d assuming that
~
~i!'"
~ . ~ a i n m e n t occurs from all sides.
;t.2
X~.\\'x~3
*
~ - ~ .
~,~}~.~..~:
.~,
~
"
~
:
~.~
.~ ~.~"
~?~
~
.~
Figure 3-8 • 1 Ax~/mmeei'i
e
~'i~'~e.
~
•
"~*Zh.
~
.
3-~ g • 11
T h e mass rate of. smoke. p r.o d u c:non
u o n c.a~.~. es.L.~nated
.
~
,
based on. the rate o f entraaned mr, smce the mass l ~ f
c o m b u s u o n products generated f r o m . t h e fire is g e ~ l y
much less
m a n m e rate ot mr e n t r a m e a m m e p m m e .
3-~g.1.2" Several e n t r a i n m e n t relations for axisymmetric fire
plumes have been proposed. Those r e c o m m e n d e d herein were
those first derived in conjunction with the 1982 edition of NFPA
204M, Guide for Smoke and Heat Venting. These relations were later
slightly improved by the incorporation o f a virtual origin a n d also
c o m p a r e d against other e n t r a i n m e n t relations [2,15].
Spill
3-~fl-.2•1" A balcony spill p l u m e is one that flows u n d e r a n d around
a balcony before rising, giving the impression o f spilling from the
balcony, from an inverted perspective (see Figure 3--78.2,1).
Scenarios with balcony spill plumes involve smoke rising above a
fire, reachimz a ceilinlz, balcony, or o t h e r significant horizontal
projection, ~ e n traveilng horizontally toward the edge o f the
"balcony." Characteristics of t h e resulting balcony spill plume
d e p e n d on characteristics o f the fire, width o f the spill plume, and
height of the ceiling above the fire. In addition, the path of
horizontal travel from the plume centerline to the balcony edge is
significant.
For situations involving a fire in a communicating space
immediately adjacent to the atrium, air e n t r a i n m e n t into balcony
spill plumes can be calculated from Equation (t=7~10):
m = 0.12 ( QHa ) l/s (g./~ + 0.25/-/)
T h e following e n t r a i n m e n t relations are essentially those
Sented in NFPA 204~, Guide for Smoke and Heat Venting [2].
cts of virtual origin are ignored since they would generally be
small in the p r e s e n t application a n d thus far can only be
adequately predicted for pool fires. T h e definition of a limiting
elevation, corresponding approximately to the luminous flame
height, is given as:
~, = o . s s s 0~2/~
Balcony
(t-g.L0.)
where:
m = mass flow rate in plume (lb/sec)
1~¢= heat release rate o f the fire (Btu/sec)
= width of t h e p l u m e as it spills u n d e r the balcony (ft)
Z b = height above the balcony fit)
H ffi height of balcony above fuel (ft)
(~)
Equation (t-gig.) is based on Law's interpretation [16] of smaib
scale experiments by Morgan a n d Marshall [17]. Equation (t-gLQ)
should be r e g a r d e d as an approximation to a complicated
problem.
where:
z, = limiting elevation (ft)
Q~ = convective portion of heat release rate (Btu/sec)
628
NFPA 92B -- MAY 2000 ROP
~"~"~~u':'~4<:~
Delete existing Equation (11)
l
where:
W = the width of the plume
w = the width of the opening from the area of origin
b = the distance from the opening to the balcony edge
3 - ~ . 3 Window Plumes.
3-~g.3.1 Plumes issuing from wall openings, such as doors and
windows, into a large-volume, open space are referred to as
window plumes (see Figure 3-8.3.1). After room flashover, the total
heat release rate can be expected to be governed by the airflow rate
through the wall opening from the open space, i.e., the fire is
"ventilation controlled." The heat release rate can be related to the
characteristics of the ventilation opening. Based on experimental
data for wood and polyurethane, the average heat release rate is
given as [20,21]:
Section
Q= 61.2 A m H~ 1/~
where:
Q = heat release rate (Btu/sec)
A~ = area of ventilation opening (fC)
H~ = height of ventilation opemng (ft)
...~:-."-,h.
This assumes th#~".',~.eat release is limited by the air supply to the
corn partment~.~.fue! ~enecation is limited by the air supl~ly, and
excess fuel
~ c" tside the compartment using air entrained
outside ~ ~
~'r t. The methods in this section are also
only va~..'~..~S~omp~i ents.having a single ventilation opening.
~.-~!-"!~~i!iii!~:~i~i~.~:~i~i~!
i
~!~!-'.'"-!~! :
iiiiiiii~i~iii:-'!liiii::~:~.~i:-:.~i~:~k%i
~.--..-';.:~.;i?
~ ~
w__
__~
+
(t-812)
o,,r'
+
Zw
Front view with draft curtains
Side
Front
Figure 3-8.3.1 Window plume.
3-~ ~t.3.2 The air entrained into the window plume can be
determined by analogy with the axisymmetric plume. This is
accomplished by determining the entrainment rate at the tip of the
flames issuing from the window and determining the height in an
axisymmetric plume that would yield the same amount of
entrainment. As a result of this analogy, a correction factor
addressing the difference between the actual flame height and the
equivalent axisymmetric plume height can be applied to the
axisymmetric plume equation according to the following relation:
Front view without draft curtains
F'~ure ~.,~_._._._._._._~1
Balcony spill plume.
3-~.~.2.2 When z~ is approximately 13 times the width, the balcony
spill plume is expected to have the same production rate as an
axisymmetric plume. Consequently, for zb>13W, the smoke
production rate from a balcony spill plume should be estimated
using Equation (t-48).
a = 2.40 a ~/5 n = l / s _ 2.1 H~
(~-o~_1.~
where:
Q = heat release rate (Btu/sec)
A m= area of ventilation opening (ft ~)
H~ = height of ventilation opening (ft)
3-8_g.2.3 The width of the plume, W, can be estimated by
considering the presence of any physical barriers protruding below
the balcony to restrict horizontal smoke migration under the
balcony. In the absence of any barriers, visual observations of the
width of the balcony spill plume at the balcony edge were made in
a set of small-scale experiments by Morgan and Marshall [17] and
analyzed by Law [16]. In these experiments, the fire was in a
communicating space, immediately adjacent to the atrium. An
equivalent width can be defined by equating the entrainment from
an unconfined balcony spill plume to that from a confined balcony
spill plume. The equivalent width is evaluated using the following
expression:
Then, the mass entrainment for window plumes is given as:
m = 0.022 Q)/s (z~ + a) s/3 + 0.0042 Q~
where:
z~ = height above the top of the window.
629
(~014)
NFPA 92B
-
-
MAY 2000 ROP
i n t e r e s t w h e n a t r i a a r e t e s t e d bv real fires as d i s c u s s e d later. T h e
ggnterline temnerature can be anoroximated from
S u b s t i t u t i n g f o r 0,~ f r o m E q u a t i o n (-1-g_J2,),
m = 0.077
( A H~1/~)~/s (z,
+ a) s/s + 0.18
A~ H~1/~
(-24-15)
l-
t~ ..............
T z = a b s o l u t e a m b i e n t t e m o e r a t u r e (°R. °K)
p~= d e n s i t y o f a m b i e n t a i r ( I b / f t s. k g / m s)
g = a c c e l e r a t i o n o f gravitv (~2.2 f t / s ~. 9.8 m / s ~)
z = h e i g h t a b o v e toD o f fuel (ft. m )
C.= s o e c i f i c h e a t oi= a i r (0.241 B t u / I b * ° F . 1.005 k l / k g * ° C I
" _ ,U;L~.7~Z, " - ' ' r . . . . . . .
c^-n:
(22)
k. . . . . . . . . . . . . . . . . .
. . . . . . . .
A
k.,
+I-._
v .......
,'
~-~* N u m b e r o f E x h a u s t I n l e t s . W h e n t h e s m o k e laver d e o t h
b e l o w a n e x h a u s t i n l e t is r e l a t i v e l y shallow, a h i g h e~thaust r a t e can
[ ~ I ~9 e n t r a i n m e n t o f c o l d a i r f r o m t h e c l e a r laver. T h i s
p h e n o m e n o n is c a l l e d o l u g h o l i n g . T h e n u m b e r o f e x h a u s t inlets
n e e d s to b e choser~:!~o {he m a x i m u m f l o w r a t e s f o r e x h a u s t w i t h o u t
olugholing are r ~ d e d .
Accordingly. more than one exhaust
inlet mavlae ~ed.
T ~ e m a x i m u m m a ~ flow r a t e . w h i c h c a n b e
efficiendv ~'a~'~sing
a s i n g l e e x h a u s t inlet, is r a v e n as [CIBSE
x--,,
, -,
__+__:
. . . .
.
^z. __^t
^:.
^I^--
.i-.^
^_+:_^
le:g'& c.f :~c F!umc. TSu~, g_G_enerallythe total plume diameter
.,,.~.~.-.:.:-::-.::.~. ~
c a n b e e s t i m a t e d as:
a= Z ~
•
(~l~}
,::.:::::~::~ .~.:~"
~. _. . ~ . . . @ ~: . ~. ,3~::;~::.
54fld~
:.
"%~i::i~:,
~ l u m e. .
d i a m e t e r fit)
Z = b e m h t fit)
/q= diameter constant
-~
x).a.= a b s o l u t e c e n t e r l i n e p l u m e t e m p e r a t u r e a t e l e v a t i o n z (°R.
ovcrc21 F l u m e 2";mn:ctcr ca-: b c c:~dmatc~ : : r,
t . ~ j .~ .
--
(18)
where:
3-8.4 P l u m e W i d t h . l = ~ ' - c = c c c,f P!'--'mc Cc.---'~-.:t v - t ~ W~.~2~. As a
p l u m e rises, it e n t r a i n s a i r a n d ~ t s ~ w i d e n s . -m.^ ~t . . . . .
:_t.,
Delete existing Equation
-II/3
Z~p=Za+9.11
L g f p~a J
T h e virtual s o u r c e h e i g h t is d e t e r m i n e d as t h e h e i g h t o f a fire
s o u r c e in t h e o p e n t h a t gives t h e s a m e e n t r a i n m e n t s as t h e w i n d o w
p l u m e a t t h e w i n d o w p l u m e f l a m e tip. F u r t h e r e n t r a i n m e n t a b o v e
t h e f l a m e tip is a s s u m e d to b e t h e s a m e as for a fire in t h e o p e n .
W h i l e t h i s d e v e l o p m e n t is a r e a s o n a b l y f o r m u l a t e d m o d e l f o r
w i n d o w p l u m e e n t r a i n m e n t , t h e r e a r e n o d a t a a v a i l a b l e to v a l i d a t e
its use. As such, t h e a c c u r a c y o f t h e m o d e l is u n k n o w n .
T,
T,
_
TO
T,
~1,~
'~"::'~
.-.@"
. , w~ h e r e : %i~j~.-.:..-.'
":-':*-':~"
"~i...'-..'::.'... . . .
..::.:::"
"~, ~ ' ~ x i m u m
mass rate of exhaust without plugholing fib/s)
. . . . . . . . . . . . . . .
~:~'.~;.~
..,.x..>~:~:#.:~T_~~=
~ g s o l u t e t e m p e r a t u r e o f t h e s m o k e l a v e r (°R~
i n e c u a m e t e r c o n s t a n t• c a n r a n g~e t r o m u.za to o.a. i t IS . ~..4:~:-$~.~::~
~::~
" t e a m l ~ i e n t t e m p e r a t u r e "I-K/
~"
" "~i~
"?::. d~"
~ = "a-n s o m
r e c o m m e n d e d t h a t v a l u e s • o f K -, b e c h o s e n s o t h a t t h e 6:al.':.
r~ltin~'~:.,':
'-'~:~.".~.'.~=
.'-'.x .~ .G e D m. . O I . s m .o k e . .l a v e r
- . . .e x h .a u s t. . . i n l e.t . l i t }
~ ~"
belOW
calculations are conservauve:
~ .
.,~.~,-:o,~ :~x :,'-~-~"
*'+" " : ~ ' ~ ~ . ~ x ~
~.">" ~ (Beta) = e x h a u s t l o c a t i o n f a c t o r ( d i m e n s i o n l e s s )
•
.
"::!i~.~*:*" "~.-'..<~
....
= 0.5 results In a conservatave e s t i m a t e of p l u m e c o n t ~ t h
-....,~::.~%,..:..
"::%':.~::~,~
walls.
..:..;.-':-*'"":i::!-!!.~i.::$'~. " ~
:.:.:. . . . . . :q~-j~ii~-:~ "%~"....
Kg = 0.25 r e s u l t s in c o n s e r v a t i v e e s t i m a t ~ i ~ e n
consi~g
I~'n
detection of the smoke plume.
""~" "'~*~..,.
"~ii "~'~':'~i~i?.--'.-.
ff
3-8.5 P l u m e T e m n e r a t u r e .
'.~.:.y
B a s e d o n l i m i t e d i n f o r m a t i o n , s u g g e s t e d v a l u e s o f B a r e 2.0 for a
c e i l i n g e x h a u s t i n l e t n e a r a wall. 2.0 f o r a wall e x h a u s t i n l e t n e a r
t h e ceiling, a n d 2.8 for a c e i l i n g e x h a u s t i n l e t far f r o m a n v walls. I t
is s u g g e s t e d t h a t d / D b e g r e a t e r t h a n 2. w h e r e D is t h e d i a m e t e r o f
t h e inlet. F o r r e c t a n g u l a ~ e x h a u s t inlets, u s e D = 2ab/(a + bL w h e r e
a a n d b a r e t h e l e n g { h a n d w i d t h o f t h e inlet.
3-8,5.1 A v e r a g e T e m o e m t u r e . B a s e d o n t h e first l a ~ : o f
t ~ e r m o d y n a m i c s , t h e a v e r a g e t e m o e r a t u r e o f t h e o l u m e is
The maximum volumetric flow rate which can be extracted
t h r o u g h a n e x h a u s t inlet• is g i v e n as:
Vma~ = 0.537 fldS/2 4To(T, - T o )
where:
{20)
wheFe"
~
= a v e r a g e p l u m e t e m p e r a t u r e a t e l e v a t i o n z (deg-F)
--ambient temperature (deg-F)
_~ =specific h e a t of o l u m e g a s e s (0.24 B t u / I b deg-F)
m = m a s s f l o r rate o f t h e n l u m e ( I b / s e c )
.V~ = maximum volumetric flow rate at T (~a/min)
W h e n t h e e x h a u s t a t a n i n l e t is n e a r t h i s m a x i m u m f l o w rate.
a d e o u a t e s e o a r a t i o n b e t w e e n e x h a u s t i n l e t s n e e d s to b e m a i n t a i n e d
to m i n i m i z e i n t e r a c t i o n b e t w e e n t h e flows n e a r t h e inlets. O n e
c r i t e r i o n for t h e s e n a r a t i o n b e t w e e n i n l e t s is t h a t i t b e a t least t h e
distance from a single inlet that would result in arbitrarily small
Velocity b a s e d o n s i n k flow. U s i n g 4 0 f o m as t h e a r b i t r a r y velocitv.
t h e m i n i m u m s e o a r a t i o n d i s t a n c e for i n l e t s l o c a t e d i n a wall n e a r
t h e c e i l i n g ( o r i n t h e c e i l i n g n e a r t h e wall) is
T h e m a s s flow r a t e o f t h e o l u m e c a n b e c a l c u l a t e d f r o m e o u a t i o n
(8) o r ( 9 ) . E o u a t i o n (8) was d e v e l o n e d for s t r o n g l y buovatat
o l u m e s , a n d for small t e m o e r a t u r e d i f f e r e n c e s b e t w e e n t h e o l u m e
a n d a m b i e n t • e r r o r s d u e to low b u o y a n c y c o u l d b e s i g n i f i c a n t .
T h i s t o n i c n e e d s f u r t h e r study, a n d . in t h e a b s e n c e of~better data. it
iS r e c o m m e n d e d t h a t t h e o l u m e e o u a t i o n s n o t b e u s e d w h e n t h i s
t e m o e r a t u r e d i f f e r e n c e is s m a l l ( < ~t°F).
3-8.5.2 C e n t a ' l i n e T e m o e r a t u r e . T h e t e m p e r a t u r e f r o m e o u a t i o n
(17) is a m a s s flow a v e r a g e , b u t t h e t e m o e r a t u r e varies o v e r t h e
D l u m e cross-section. T h e p l u m e t e m p e r a t u r e is tzTeatest a t t h e
c e n t e r l i n e o f t h e n l u m e , a n d t h e c e n t e r l i n e t e m p e r a t u r e is o f
Smi~ = 0 . 0 2 3 f l - ~ - ~
63O
~l~
NFPA 92B ~
MAY 2000 ROP
where:
where:
v,= limiting average velocity (fpm)
Q = heat release rate o f the fire (Btu/sec)
z = distance above the base o f the fire to the bottom o f the
o p e n i n g fit). (See Figure 3 4 0 ~ 3-12.2.)
~ai= = m i n i m u m edge-to-edge senaration betweeu inlets (ft)
V = volumetric flow rate (~S/min)
~'= exhaust location factor (dimensionless)
It is suggested that the m i n i m u m senaration between inlets 9f
enuation (21) be a d h e r e d to whenever V J V
~
half.
v, should not exceed 200 f t / m i n . This equation should n o t be
used when z < 10 ft. In the other case, the o p e n i n g to the
communicating space is located above the position o f the smoke
layer interface, in which case Equation (24) is used to calculate the
limiting average velocity (setting v = v,), where Tf - T o is the value of
A T from Table 3-5 a n d T f = A T + T o.
3-10" Volumetric Flow Rate. For practical reasons, exnressine the
stIIoke production rate in terms of-a volumetric rate (~S/min~
might be preferred over ~, E0ass rate. This nreference can be
~;commp~lated by dividing the mass flow rate by the density o f
smoke..
Large-volume
V= 60 m / Q
space.
(22)
where:
Communicatingspace
~_ = density of smoke (Ib/'ft s)
The volumetric flow rate ~¢termined using the above eauation is at
the smoke laver temnerature. For a smoke m a n a g e m e n t system
0,~;~imled to onerate u n d e r euuilibrium conditions (see ]-7.1 }. the
smoke exhaust system should be designed to nrovide sufficient
volumetric exhaust canacitv at the temperature o f the smoke laver.
3-110 Maximum Air Supply Velocity. The supply velocity o f the
makeup air at the perimeter o f the large, o p e n space m u s t - ~
be limited to sufficiently low values so as n o t to deflect the fire
plume significantly, which would increase the air entrainment rate,
or disturb the smoke interface. A m a x i m u m makeup supply
velocity o f about 200 ft/rnin (1 m / s e e ). is .re.commended, based on
flame deflection data [22].
" " "
•
•
o
0
Measurement of distance above base of fire to
bottom of opening.
•
Chapter 4 Equipment and Controls
may not be detrimental.
3-12 0 O p p o s e d Airflow Requirements.
~.:~
,.~.
"~i~~"
~ ' . 1 T h e dynamics, buoyancy, plume, a n d stratification of the
~otential fire, together with the width and height of the largevolume space must all be considered when selecting the smoke
m a n a g e m e n t system. Generally, the HVAC systems designed for
these spaces do n o t have the capacity for use as a smoke
m a n a g e m e n t system, nor are the supply and exhaust air grilles
located for their p r o p e r use in such a system. In most cases,
therefore, a dedicated smoke m a n a g e m e n t system should be
considered•
3-120.1 To prevent smoke originating in a cummin
sp~:..:~{:..[~.,.
from propagating into the large space, the c o m m u m c a t
v ~ c e :~
must be exhausted at a sldiicient rate to cause ..~.~..~,%rag~
velocity in the o p e n i n g from the large space ~ ~ . l
~->. ,.
limit. The limiting average velocity, v, can . . ~ c a l c u i ~ : ~
~!~':'"~':'!~
~.:#~
.~
#~
.-~:,-% i$.-':i$:~
~ (~_~)
v = 38 [gH ( T f - To) / ( Tf + 460) ] '/=
where:
:~'~ .....
v = air velocity (ft/min)
= acceleration o f gravity ($2.2 f t / s e c ~)
= height of the o p e n i n g (ft)
~jo = temperature of heated smoke (°F)
= temperature of ambient air (°F)
For example, with H = 10 ft, T~ = 165°F
sprinklered spaces) and T o = 70°F, the
270 fpm. For the same conditions with
realistic for unsprinklered spaces), the
594 ft/min.
4-1.2 Some existing large-volume spaces that have glass walls or
skylights have been reported to experience temperatures up to
200°17 (93°C) because of solar loads. Any building materials
located in such areas n e e d to be capable of operating in this
heated environmenu
#:
4-2 Exhaust Fans. Exhaust fans should be selected to operate at
the design conditions of the smoke and fire. While dilution with "
ambient air might significantly cool down the fire temperature,
there can be instances where the direct effects of the fire will he on
the equipment.
(considered realistic for
limiting velocity becomes
Tf = 1640°F (considered
limiting velocity becomes
4-3 Makeup Air System. The simplest m e t h o d of introducing
makeup air into the space is t h r o u g h direct openings to the outside
such as doors a n d louvers, which can be o p e n e d u p o n system
activation. Such openings can be coordinated with the
architectural design and be located as required below the design
smoke layer. For locations where such openings are impractical, a
l~=d-mechanical
supply system can be considered. This could
possibly be an adaptation of the building's HVAC system if
capacities, outlet grille locations, and velocities are suitable. For
such systems, means should be provided to prevent supply systems
from operating until exhaust flow has been established to avoid
pressurization o f the fire area. For those locations where climates
are such that the damage to the space or contents could be
extensive during testing or frequent inadvertent operation of the
system, consideration should be given to heating the makeup air.
3-120.2 To prevent smoke originating in the large-volume space
from propagating into the communicating space, air must he
supplied from the communicating space at a sufficient rate to
cause the average air velocity in the o p e n i n g to the large space to
exceed a lower limit [i.e. the limiting average velocity (v,) in
Equation (g~24)]. Two cases can be differentiated. In o n e case,
the o p e n i n g to the communicating space is located below the
position of the smoke layer interface and the communicating space
is exposed to smoke from a plume located near the perimeter of
the open space, in which case the limiting average velocity, v,, can
be estimated from:
v, JoCpm)--= 17 [ Q,/z] ~/s
(gg24)
4-4 Control Systems.
631
NFPA 92B
-
-
MAY 2000 ROP
4-4.1 Simplicity. Simplicity should be the goal of each smoke
management control system. Complex systems should be avoided.
Such systems tend to confuse, might not be installed correc.tl~,
might not be properly tested, might have a low level of reliabdity,
and might never be maintained.
4-6 Materials.
4-4.2 Coordination. The control system should fully coordinate
the smoke management system interlocks and interface with the fire
protection signaling system, sprinkler system, I-IVAC system, and
any other related systems.
4-6.1 Materials used for systems nrovidin~ smoke control should
g9nform to NFPA 90A. Standard for the InstaUation of AirConditionin~ and Ventilatin~ S~stems. and other aut)licable NFPA
documents.
4-4.$ HVAC System Controls. Operating controls for the HVAC
system should accommodate the smoke management mode, which
must have the highest priority over all other control modes.
4-6.2 Duct materials should be selected and ducts desi~,ned to
convey smol~e, withstand additional nressure (both Dosftive and
negative~ bv the suonlv and exhaust fans when ooeratin~ in a
smoke-control moc[e_ and maintain their structural integrity durin~
the neriod for which the system should onerate.
4.4.4 Response Time. :]'he smoke management system activation
should be initiated immediately after receipt of an appropriate
activation command. The smoke management system should
activate individual components such as dampers and fans in
sequence as necessary to avoid physical damage to the equipment.
Careful consideration should also be given to the stopping of
operating equipment in proper sequence as some fans take a long
time to wind down, and the closing of dampers against airflow can
cause serious damage. The total response ume, including that
necessary for detection, shutdown of operating equipment, and
smoke management system start-up, should allow for full
operational mode to be achieved before the conditions in the
space exceed the design smoke conditions.
~i,$ Euuinment including, but not limited to. fans. ducts, and
balance damners should be suitable for their intended use and the
nrobable temneratures to which they may be exposed.
5L
4-70th,
building
serving t
4-4.5_* Control System S~Fc-:-'=: Verification and
Instrumentation. Every system e~ed~ should have means of
ensuring it will operate if ~ d e d a c f i ~ t e d . The means and
uf£.f..q.~l~ will vary according to the complexity and importance of
the system. S-:Fc:-A:L~n ~z'-cc: -^.--~"~.cl'.:~c "~c fc!!:;'.~=g:
^x
(-~
I~.4
~^ ----A
;. . . . . . . ' ^ : ^ - ^C
.k-...'--: . . . . . .
: . . . .
. . . . . . . . . . . .
r . . . . . . . . . . . . . . . . . . . . . r~, - ~ - ' r . . . . . .
.
",
Testing
~ . 4
A^..'.^.
. . . . . . . . . .
5-1.1
:--.I..A^
*I~ . . . . . . . . . .
e
~ . . ~ :
. . . . . . . . .
A . . . . .
*.
.
.
.
.
C Systems. When other systems in the
)art of the smoke management system
area, refer to NFPA 92A, Recommended
..S3s~ns, for guidance.
~-II
.:
....
mr provides recommendations for the testing of
lent systems. Each system should be tested against
a criteria. The test procedures described herein
the following three categories:
:+
:Component system testing
Acceptance testing
Periodic testing and maintenance
5-1.2 It is recommended that the building owner, designer, and
authority having jurisdiction meet durin~ the planning stage of the
project and share their thoughts and objectives concerning the
smoke management system contemplated and agree on the design
criteria and the pass/fail performance tests for the systems. Such
an agreement will help overcome the numerous problems that
occur during final acceptance testing and facilitate obtaining the
certificate of occupancy.
.....
,~,
5-1.:$ Contract documents should include all acceptance testing
procedures so that all parties have a clear understanding of the
system objectives, testing procedures, and pass/fail criteria.
+5"-
dcw.ce= ~r me~q~ == z p ~ r ~ r : a t e .
4-4.6 Manual Control. Manual control of all systems should be
provided at a centralized location. Such controls should be able to
override any interlocking features built into the automatically
operated system. See NFPA 92A, Recommended Practice for Smolm
Control Systems, for devices that should not be overridden.
5-2 Component System Testing.
5-2.1 General. The intent of component system testing is to
establish that the final installation complies with the specified
design, is functioning properly, and is ready for acceptance testing.
Responsibility for testing should be d e f i n e d clearly prior to
component system testing.
4-5 Electrical Services.
4-5.1 Electrical installations should meet the requirements of
NFPA 70, National Electrical Coder.
5-2.2 Prior to testing, the party responsible for this testing should
verify completeness of building construction, including the
following architectural features:
4-5.2 Normal electrical Dower serving air conditioning systems will
generally have sufficient reliability for nondedicated zoned smokecontrol svstems.
........................
C.
.
.
.
.
:--.
u~l:.v/!!no.
. . . .
T~c
!
~'=..^
t............
~I*.^--
c.
.
.
.
oT=tc.":'~ : ~ c : : : ~
be .~m.7.gccl f: . . . . . . . . . . . . . . . . .
.
:--.
pc . . . . . . . . .
. . . . .
~
^--
^2---
(1) Integrity of any partition, floor, or other member intended to
resist smoke passage
(2) Firestopping
(3) Doors and closers related to smoke control
(4) Glazing that encloses a large-volume space
~re~.er
: . . . .
b c I ~ c : t c ~ ~ : =.-ca= ~ = t
~ . . . . . m . :Fzcc.
.'----
;"~u!?q. n e t
5-2.3 The operational testing of each individual system component
should be performed as it is completed during construction.
These operational tests will normally be performed by various
trades before interconnection is made to integrate the overall
smoke management system. It should be documented in writing
that each individual system component's installation is complete
4-5.$ Whether Or not standby power is needed should be
considered for smoke-control systems and their control svstems.
632
NFPA 92B ~
MAY 2000 ROP
and the component is fimctional. Each component test should be
individually documented, inducting such items as speed, v o l u m e ,
sensitivity calibration, voltage, and amperage.
55.4.4 The acceptance testing should include demonstrating that
the correct outputs are produced for a given input for each control
sequence specified. Consideration should be gaven to the
following control sequences so that the complete smoke
management sequence is demonstrated:
5-2.4 Testing should include the following subsystems to the extent
that they affect or are affected by the operation of the smoke
management system:'
(1) Normal mode
(2) Automatic smoke management mode for first alarm
(3) Manual override of normal and automatic smoke
management modes
(4) Return to normal
(1) Fire protective signaling system (see NFPA 72, NationalFire
Alarm Code)
(2) Energy management system
(3) Building management system
(4) HVAC equipment
(5) Electrical equipment
(6) Temperature control system
(7) Power sources
(8) Standby power
(9) Automatic suppression systems
(10) Automatic operating doors and closures
(11) Other smoke-control systems
(12) Emergency elevator operation
5-3.4.5 It is acceptable to perform acceptance tests for the fire
protective signaling system in conjunction with the smoke
management system. One or more device circuits on the fire
protective signaling system can initiate a single input signal to the
smoke management system. Therefore, consideration should be
given to establishing the appropriate n u m b e r of initiating devices
and initiating device circmts to be operated to demonstrate the
smoke management system operation.
5-3 Acceptance Testing.
5-3.4.6 Much can be accomplished to demonstrate smoke
management system operation without resorting to demonstrations
that use smoke or products that simulate smoke.
5-$.1 The intent of acceptance testing is to demonstrate that the
final integrated system installation complies with the specific design
and is functioning properly. Representatives of one or more of the
following should be present to grant acceptance:
5-3.5 Large-Volume.Space Smoke Management Systems.
5-3.5.1 The I ~ e
space can come in many configurations,
each of w h i c [ ~ - ~ . t s own peculiarities. They can be tall and thin;
short and ~ " e; " ~ b a l c o n i e s and interconnectin~ floors; be open
or c l o s e ~ ~ l ' ~ . ~ o r s ;
have corridors a n d stmrs for use in
evacu: ~ ' ~ a v e
o ~ ' ~ ' ~ o s e d walls and windows (sterile tube);
and
be ~'portion ot ~ o t e l , hospital, shopping center, or
az.~S~....gific smoke gt~n a g e m e n t criteria must be developed for
(1) Authority having jurisdiction
(2) Owner
(3) Designer
All documentation from component system testing should be
available for inspection.
5-5.2 Test Parameters. The following parameters need to be
measured during accepumce testing:
(1)
(2)
(3)
(4)
(5)
(6)
Total volumetric flow rate
Airflow velocities
Airflow direction
Door-opening forces
Pressure differentials
Ambient temperature
5-3.$ Test Equipment. The following equipme
to perform acceptance testing-
5-$.5.2%~K~ffy the exact location of the perimeter of each largevolume s ] ~ J ~ . ~ o k e management system, identify arty door
" ~ t h a t space, and identify all adjacent areas that are m
~.~en]ngs ir
i and that are to be protected by airflow alone. For
ings, the velocity must be measured by making
~ippr0#tiate traverses of the opening.
~,,
~,
.~.'5.3 With the HVAC systems in their normal mode, measure
~ffressure differences across all door barriers and airflow velocities
at interfaces with open areas. Using the scale, measure the force
necessary to open each door.
htt
5-8.5.4 Acdvate the smoke management system. Verify and record
the operation of all fans, dampers, doors, and related equipment.
Measure fan exhaust capacities, air velocities through inlet doors
and grilles, or at supply grilles if there is a mechanical makeup air
system. Measure the force to open exit doors.
electronic manometer (instrument
,.5
Pa) and 0-0.50 in. w.g. ( 0-125 Pa)
ibing
(2) Scale suitable for measuring door--open
(3) Anemometer, i n d u d i n g traversing equipme
(4) Ammeter
(5) Door wedges
(6) Tissue paper roll or other convenient device for indicating
direction of airflow
(7) Signs indicating that a test of the smoke management system
is in progress and that doors should not be opened
(8) Several walkie-talkie radios have b e e n found to be useful to
help coordinate equipment operation and data recording
5-$.5.5 Measure a n d record the pressure difference across all
doors that separate the smoke management system area from
adjacent spaces and the velocities atinterfaces with open areas.
5-3.6 Other Test Methods.
5-3.6.1 General. The test methods previously described should
provide an adequate means to evaluate the smoke management
system's performance. Other test methods have been used
historically in instances where the authority having jurisdiction
requires additional testing. These test methods have limited value
in evaluating certain system performance, and their validity as a
method of testing a smoke management system is questionable.
5-3.4 Testing Procedures. The acceptance testing should consider
inclusion of the procedures described in 5-3.4.1 through 5-3.4.6.
5-3.4.1 Prior to beginning acceptance testing, all building
equipment should be placed in the normal operating mode,
including equipment that is not used to implement smoke
management, such as toilet exhaust, elevator shaft vents, elevator
machine room fans, a n d similar systems.
5-3.6.2 , As covered in the preceding chapters, the dynamics of the
fire plume, buoyancy forces, and stratification are all major critical
elements in the design of the smoke management system.
Therefore, to test the system properly, a real fire condition would
be the most appropriate and meaningful test. But there are many
valid reasons why such a fire is usually not [~ractical in a completed
building. Open flame/actual fire testing might be dangerous and
should not normally be attempted. Any other test is a
compromise. If a test of the smoke management system for
building acceptance is mandated by the authority having
jurisdiction, such a test condition would become the basis of
design and might not in any way simulate any real fire condition.
More importantly, it could be a deception and provide a false sense
of security that the smoke management system would perform
adequately in a real fire emergency.
5-$.4.2 Wind speed, direction, and outside temperature should be
recorded for each test day. If conditions change greatly during the
testing, new conditions should be recorded.
5-3.4.3 ff standby power has been provided for the operation of the
smoke management system, the acceptance testing should be
conducted while on both normal and standby power. Disconnect
the normal building power at the main service disconnect to
simulate true operating conditions in this mode.
633
NFPA 92B -- MAY 2000 ROP
Smoke b o m b tests do NOT provide the heat, buoyancy, and
e n t r a i n m e n t o f a real fire and are NOT useful to evaluate the real
p e r f o r m a n c e o f the system. A system designed in accordance with
this d o c u m e n t a n d capable of providing the i n t e n d e d smoke
m a n a g e m e n t might n o t pass smoke b o m b tests. Conversely, it is
possible for a system that is incapable of providing the i n t e n d e d
smoke m a n a g e m e n t to pass smoke b o m b tests. Because of the
impracticality of conducting real fire tests, the acceptance tests
described in this d o c u m e n t are directed to those aspects of smoke
m a n a g e m e n t systems that can be verified.
Chapter 6 Referenced Publications
6-1 The following d o c u m e n t s or portions t h e r e o f are referenced
within this guide and should be considered as part of its
recommendations. The edition indicated for each r e f e r e n c e d
d o c u m e n t is the current edition as of the date of the NFPA
issuance of this guide Some of these d o c u m e n t s might also be
referenced in this guide for specific informational purposes and,
therefore, are also listed in A p p e n d i x F.
6-1.1 NFPA Publications. Nadonal Fire Protection Assodation, 1
Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.
5-3.7 Testing Documentation. U p o n completion o f acceptance
testing, a copy of all operational testing d o c u m e n t a t i o n should be
provided to the owner. This d o c u m e n t a t i o n should be available
for reference for periodic testing and maintenance.
NFPA 70, National Electrical Code°, 4.0061999 edition.
NFPA 72, National Fire Alarm Code*, 400~1996 edition.
NFPA 90A, Standard for the Installation of Air-conditioning and
Ventilating Systems, 4-00~1999 edition.
NFPA 92A, Recommended Practice for Smoke-Control Systems, 4002~
2000 edition.
NFPA 101 ®, Life Safer3 Code®, ~ 0 4 2000 edidon.
NFPA 204M-, Guide for Smoke and Heat Venting, -1-0Ot-1998 edition.
5-3.8 Owner's Manuals and Instruction. Information should be
provided to {he owner that defines the operation and maintenance
of the system. Basic instruction on the operation of the system
should be provided to the owner's representatives. Since the owner
might assume beneficial use of the smoke m a n a g e m e n t system
wherever there are completion o f acceptance testing, this basic
instruction should be completed prior to acceptance testing.
6-1.2 Other Publications.
5-3.9 Partial Occupancy. Acceptance testing should be p e r f o r m e d
as a single step when obtaining a certificate of occupancy.
However, if t h e building is to be completed or occupied in stages,
acceptance tests of the entire system should be conducted in order
to obtain temporary certificates o f occupancy.
6-1.2.1 UL Publications. Underwriters Laboratories Inc., 333
Pfingsten Road, ~ b r o
~k, IL 60062.
UL 555, S t a ~ J o r
Control S ~ s ~
5-3.10 Modifications. All operation a n d acceptance tests should
be p e r f o r m e d on the applicable part of the system wherever there
are system changes a n d modifications. Documentation should be
u p d a t e d to reflect these changes or modifications.
Saf,
Fire Dampers, 1999.
y Leakage Rated Dampers for Use in Smoke
19~..":~.'...
5-4 Periodic Tesdng.
5-4.1 During the life of the building, maintenance is essential to
ensure that the smoke m a n a g e m e n t system will p e r f o r m its
i n t e n d e d function u n d e r fire conditions. Proper maintenance of
the system should, as a minimum, include the periodic testing of
all e q u i p m e n t such as initiating devices, fans, dampers, c o . ~ . ~ ,
doors, and windows. The e q u i p m e n t should be m a i n ~ i : , .
accordance with the manufacturer's recommendationm~:See N ~ A
90A, Standard for the Installation of Air-Conditioning ~tila~'. ~ ~_~:~.,,~,,
Systems, for suggested m a i n t e n a n c e practices.
"~#ji~.~:,,.-.~.":~-" ~
"%-..'.:'$~::.
5-4.2 The periodic tests should d e t e r m i n e t h ~ . C ; ~ l e u
~
continue to operate in accordance with t h e . ~ ' p r o v e a ~
preferable to include in the tests both t h ~ . ' ~ a s u r e m e n
fall
,
quantities a n d the pressure differentaal
"
" s-.~
:'::-.-.~
t~.~:
.., ~'.:~::'
:~..:-':~:.
(1) Across smoke barrier openings
(2) At the air makeup supplies
(3) At smoke exhaust e q u i p m e n t
Explanatory Material
anoroach [CooDer et al. 1982 and Peacock an d Babrauka, (1991)]
is to use linear ]nteroolation of the point measurements. U~in~
temperature data. the interfaces are at the heights at which the
temperatur~ i* as follows=
z-~__c~-
.#::
r~ + r~.
where."
j~":
~ m L = the temnerature in the smoke laver
= the temperature in the cold lower laver
_C = an interoolation constant with values of 0.1--0.2 for the first
incfication o f smoke a n d 0.8-0.9 for the smoke laver interface,
resnectivelv.
All data points should coincide with the acceptance test location to
facilitate comparison measurements.
5-4.3 The system should be tested at l e ~ t semiannually by persons
who are thoroughly knowledgeable in the operation, testing, and
m a i n t e n a n c e of the systems. The results of the tests should be
d o c u m e n t e d in the operations a n d m a i n t e n a n c e log and made
available for inspection. The smoke m a n a g e m e n t system should be
operated for each sequence in the current design criteria. T h e
operation of the correct outputs for each given input should be
observed. Tests should also be c o n d u c t e d u n d e r standby power, if
applicable.
A-l-4 Transition Zone. (See aho A-3-8.1.2 for further details. I
A-1-5.4.1 The p e r f o r m a n c e obiective o f automatic snrinklers
installed in accordance with I~FPA 13. Standard fur ¢h¢ Installation of
St~rinkler S~stems. is to provide fire control whicl~ is defined as
follows: L~mitin~ the size of a fire by distribution of water so as to
decrease the heat release rate and ore-wet adjacent combustibles.
while controlling ceilin~ ~as temoeratures to avoid structuvo,]
damage. A limited n u m b e r of investi~-ations have been undertaken
in which full-scale fire tests were conc/ucted in which the ~pHnkler
system was challenged but nrovided the expected level o f
oerformance. These investigations indicate that. for a fire control
situation, the heat release rate is limited but smoke can continue to
be oroduced. However. the temperature of the smoke is reduced.
5-4.4 Special arrangements might have to be made for the
introduction of large quantities o f outside air into occupied areas
or computer centers when outside temperature and humidity
conditions are extreme, and such u n c o n d i t i o n e d air might damage
contents. Since smoke m a n a g e m e n t systems can override limit
controls such as freezestats, tests should be c o n d u c t e d when
outside air conditions will n o t cause damage to e q u i p m e n t and
systems.
Full-scale sprinklered fire tests were conducted for open-plan office
scenarios [Madrzvkowski and Vettori 1992. Lou~heed-199-7]. These
tests indicate that there is an exnonential d e c a v ] n the heat release
634
NFPA 92B -- MAY 2000 ROP
rate for the snrinklered fires after the sDrinklers are activated and
achieve control. The results of these tes~ ~lso in~iicate that;
design fire with a steady-state heat release rate of 500 kW provides a
¢0nserv~0ve estimate fol" i~ spdnklgred open-plan 9ffice.
temperature= and -:~nd :'¢!vc:'-e: =-e n~t g!:'zn. T~..c:: dam :'.¢¢d :v
bc ~:cd :;-=.h c~'a~c.n._
A-1-6.$ O n e source of data is the ASHRAE Handbook of
~'undamentals. Chanter 26. "Climatic Design Information." It is
su~e~%~d that Lhe 99.6% h e a d n g dry bull~ (DB/ t e m u e r a t u r e a n d
the 0.4% cooling DB t e m n e r a t u r e be used as the winter and
~umrqe I" design ~ondition~ resnectiveiv. It is also suggested that the
~1% extreme winql velocitv be used as the desires con-cl-ition. Where
~vailabl¢. m o r e ~ite-sDetfic data should be consulted.
T h e r e is lilnited full-scale test data available for use in determining
design fire size for other sorinklered occuDancies. Hansell a n d
Morgan I~RE 2581 provide conservative estimates for the
¢onvectivg heat release rate based on OK fire statistics: 1 MW for a
s_.12dnkered office, 0.5-1.0 MW for a sDrinklered hotel b e d r o o m and
5 M W f o [ a sprink]ered retail occuoancv. These steady-state desires
fires assume the area is fitted with standard resnonse sndnklers.
#-2-4.1.3 A sDreadsheet model or other time step model can be
¢gBstructed using the algebraic ~quations contained in Section $ in
order to calculate the nosition of a smoke laver interface over time.
both with and without-smoke exhaust in operation. This a n n r o a c h
involves the calculation of the mass of smoke entering the smoke
layer, the temDerature of the smoke entering the laver, and volume
of smoke removed from the laver bv the mechanical exhaust. The
~teps usgd to determine the Dosition of the smoke laver interface
are as follows:
Full-scale fire tests for retail occupancies were conducted in
AOstralia lBenn etts et al.l. T h e s e tests indicated that for some
commofi I'etail O~30ets ¢qlQthing and book stores) the fire is
controlled a n d eventually extinguished with a single sDrinkler.
These te~t# also indicated that the sprinklers mav have difficulty
~uppres~iog a fire in a s h o p such as a toy store with a high, fuel
load.
(a) Select the time step for the calculation. A.£
(b) Determine the design fire (e.~.. steady-state, growing fire.
Full-scale fire tests were conducted for a variety of occunancies
(retail. cellular offices and libraies) in the United Kingdom [
Ghosh 1997].
F~ll-scaie fire tests were conducted for comDact mobile storage
svstems used for d o c u m e n t storage. Information on tests
conducted in 1979 on behalf of the Library of Congress is orovided
ill Aooendix G of NFPA 910 Protection of Libraries and Li-brarv
Collections. Subseouent full-scale fire tests were conducted for the
Librarv of Congress-Archives II and the National Library of Canada
and showed that fires in compact mobile are difficult to extln~uish
[Lou~heed et al 1994].
&-1-5.4.2 During the initja~ active phase of the fire with the
sprinklers ooeratlng, the smoke laver remains stratified u n d e r the
~veraging this value with the incremental mass from the previo¢~
the moke 1
will
I ra id
d
s
t o r o u g h q u t the volume a~ buoyancy decays,
tUar_m~
(e) Calculate the temperature of the smoke entering the u n d e r
laver. The eouations for calculating temnerature can be founcl in
v
Tabte ~5~
(f) Add the mass of smoke enterin~ the UDDer laver to the total
mass of smoke to obtain the new total mass of smoke in the UDDer
m l * mi_e_m~
application density of 0.1 g p m / f t ~ and <500 kW at an appligation
densltv of 0.2 ~ n m / f t ~. For higher heat release rates, the smoke
temperature will be above a m b i e n t and will be buoyant as it leaves
the sDrinklered area.
where."
mz = to~al mass of smok¢ of smgke at eqd of previous time steD
m2 = new total smoke mass in u p p e r laver (kg)
For low heat release rate sorinkered fires, the smoke is mixed over
tOe height of the comnartrnent. The smoke flow t h r o u g h large
oDenings into an atrium will have a constant temnerature with
(g~ D~;termine the new temperature of the u p p e r laver via
conservation of ener~,v. The higher the laver temperature, the
greater its volume angel lower the smoke laver interface. Therefore,
it is conservative to assume no h e a t losses f r o m the UDDer laver to
the c o m p a r t m e n t boundaries over time.
With higher heat release rates, a h o t UDDer laver will be formed.
T h e temnerature of the UDDer laver will be between the ambient
temperature and the oDeratina temnerature of the sorinkler. If the
smoke is hotter than the sprinkler 9perating temp¢l'ature, f~rth~r
sDrinlders will be activated and the smoke will be cooled. For
design DUrDOSeS. a smoke temDerature eGuivalent tO the operating
temperature of the sDrinklers can be assumed.
T~--__LmlZ1+ miT1)Z_~°C
(h) Determine the densitv of the new uDDer laver:
A 1 $.~ Wcatkcr !:-£~rmafic.n f~r ma=:y N~r'~ ?~mcrica=: and :~mc
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
~
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
~
.
.
.
.
.
.
.
.
.
.
.
.
p
~j
~
~
+ 2 7 3 ) / ( T: + 273) ( k g / m 3)
F:~d~.m~r~:a::. ,~?.v.:t ;':cz:kcr data "; co!looted at municipal airpcTt~
(i) Determine the volume of the new UDDer laver:
635
NFPA 92B -- MAY 2000 ROP
~,xampl¢ 5, In a ? n e tenth scale model, the following clear heights
were observed: 9.5 m at 96 seconds. 1.5 m at 85 seconds and 1.0 m
at | 5 2 seconds. What are the corresvondimt clear heights for the
full scale facility?
~__~ze_tmLt
(i) Subtract the volume of the smoke removed, if anv. via
mechanical ventin~ over the riven time sten to determine the final
uDDer laver volume
(1~) Determine the new smoke laver interface oosition as a
function of the final u n d e r laver volume, a n d the tteometrv of the
sln?ke reserv?ir. For re¢tangular geometries, t h e s m o k e laver
position is calculated as follows:
Layer interface (m) = ceilin~ height - - (final u p p e r laver volume
LE~.)/area of reservoir)
F?r the first clear height a n d time hair of za ffi 2.5 m at tz ffi 26 s:
2.5(10/1) = 2 5 m
and
(B Return to step (d) a n d use the newlv calculated laver
interface to calculate the mass of smoke enterimt the smoke laver in
the subseouent time steP.
=t.[~-[
tF
= 26(1011) i n = 8 2 s
tl )
Existing A-3-1.1.3 remains unchanged.
The other clear hei~rht and time hairs are claculated in the same
lll~nner. ~nd thev a r e all listed belo~.
Existing A-3-1.2.1 remains unchanged.
Existing A-3-1.2.2 remains unchanged.
Scale Model Observation
The following examples are included to provide insight into the
w~y that the Froude mo~leling scaling relations are used. -
Qlear Height (m~
F,xample 1, W h a t scale model should be used for # mall where the
smallest area of interest is the floor to ceilin~ height on the
balconies which i s 3 m ?
-
~
~.~.~'~.
Existi
n~:~%
t
: r ~ "
Full Scale Facilltv Prediction
Clear H e i g h t (m~
15~
10
480
unchanged.
~ o t e tha~ il~ is essential that the flow in model is fvlly develope0
l-sca
r onen-nlan offices [Madrzvkowski
l~urbulent flow. a n d to achieve this it i~ suggested that areas of
a l t ~ e t t o ' i ~ 1 9 9 2 a n d L ~ l t h e e d 19971 "have shown that. once the
interest in the scale model be at least 0.3 m. The corresoondin~
~- :
snri~l~ri-~'tx~/~ control of t-he fire b u t are n o t immediately able to
floor to ceilin~ height of the model should be at least 0.~ m. Set I
e'xtin~'it
due to the fuel configuration, the heat release rate will
ffi 0.3 m a n 0 /1:= 3 m. then /~/-/1: ffi 0.1. Therefore. the model can b ~
d e cr eas e"~.
"~'~'~aat~enti ailv a s follows~
9he tenth ~cale.
~ - ~
.... ~.~
Exara~le 2. The desi£m fire for a snecific facility is a constant fire
9f 5000 kW, What size fire will be n e e d e d for a one tenth s c a d ~
1~/-~ =0.1
"e~ ~-' ~ ' kO a ct t -
.~._...-
(1 .~5/2
Q~ = Qe/TM /
t lF )
4~'" ~(ti: the heat release rate at time t after smSnkler activation
(Btu/sec~
.(~ffi the heat release rate at sprinkler a~ztivation~ (Btu/s~
¢= time after sDdnkler activation (sec)
k = decay c o n s e n t (sec'll
ff~>~.,~:..
= 5000(0.1)'/.~+~+15.8~".~
"~
~.~
~'~.
"<~
:#~:<"
'Sg"
:~
Estimates for the decay constant for office occunancies orotected
with a discharge density o f 0.1 t r o m / ~ ~ are 0.0025 for situations with
li~tht fuel Ioacls in shielded a r e ~ [Madrzvkowski a n d Vettori 19921
and 0.00155 see'* for situations with h e a w loads rLou~heed 19971.
Examole 3, T h e smoke exhaust rate for a full fft~/iff~,facik'~ is 250
mS/sec, what is the smoke exhaust rate for a one ~ : a l e
model?
"7
Vfan, m "- V
,"
\5/2
f£)
)
Delete existing A-3-B.2.2.
=250(0.1)
5n = 07.9m3/sec
A-$-4 A n o t h e r case for which a solution has been deveioned is
deDicted in Figure A-$-4. In this case. the a m b i e n t interior air
wi(hin the large snace has a constant t e m n e r a t u r e m a d i e n t
0 ; ¢ m p e r a t u r e c h a n g e per unit height~ f r o m floor level to the
~Hing. This case is less likely t h a n temneratures that anuroximate._
~ ¢ n function. For the linear temperature profile, the m a x i m u m
h~i~l~t that smoke will rise can be cierived from the vioneerin~
work of Morton. Tavtor. and T u r n e r f l l l .
Examble 4. The walls of the full scale facility are made of
concrete. W h a t is the impact of constructin~ the walls of a one
tenth scale model of ~-¢os'um board?
of brick is 1.7 k W i m "4 K ~ s.
Figure A-3-4
The ideal thermal orooerties of the model can be calculated as
(Figure was unavailable for the ROP)
.
(kpc).,,. = (kpc)~, r
-
= (1.7)(0.1) o.9 = 0.21kW2m-4K-2s
I
~
(DT/ d,zY~/s
where'.
a~ = m a x i m u m height of smoke rise above fire surface (ft~
.Q. = convective vortion of the heat release rate tBtu/sec~
AT/d~ffi rate of ¢liange of alnbient temnerature with resnect to
heicht ( °F/ft]
The value for ~_ . _w s u m board is 0.18 kW~ In "4 K ~ s which is close to
the ideal value above, so that the ~t~rnsum b o a r d is ~ood match. It
should be n o t e d that usin~ class windows for video and
PhotograPhs would be m o r e i m n o r t a n t than scalin~ of thermal
properties.
636
NFPA 92B ~
MAY 2000 ROP
T h e convective Dortion of t h e h e a t release rate. O. can be
estimated as 70 p e r c e n t of t h e total h e a t release r~t¢,
A l t h o u g h t h e equations were develoned for natural venting.
nhvsical a n d n u m e r i c a l m o d e l i n g studies c o n d u c t e d iolndv bv
)~SHRAE a n d N]RC [ L o u g h e e d a n d H a d i i s o n h o c l e o u s 1997.
L o u g h c e d . Hadiisonhocleous. M c C a r t u e v a n d T a b e r 1999 a n d
HadiisQphoclegtjs. L o u g h e e d a n d Can 1999] indicate they are also
aoolicable to m e c h a n i c a l e x h a u s t systems. T h e s e studies u s e d
oh-vsical models, which were 5.5 m a n d 19.9 m in h e i g h t with
volumetric flow rates o f u o to 25 m S / s e c for a single e x h a u s t inlet
(average e x h a u s t inlet velocities o f u n to $0 m / s e c L T h e nhvsical
m o d e l results indicated t h a t t h e s m o k e d e n t h could be r e d u c e d to
a n o r o x i m a t e l v 10% o f t h e clear h e i g h t bv u s i n g multiple e x h a u s t
inlets to m i n i m i z e t h e m a s s / v o l u m e t r i c flow rate at each e x h a u s t
inlet. T h e n u m e r i c a l m o d e l studies indicated t h a t t h e results could
be scaled to h i g h e r atria.
T h e m i n i m u m O_ r e o u i r e d to overcome the a m b i e n t t e m p , rature
difference a n d d~ive tlae s m o k e to t h e ceiling (z = /i3 follows
readily f r o m E o u a t i o n f5/.
= m i n i m u m convective h e a t release rate to overcome
stratification ( B t u / s e c )
/-/= ceiling h e i g h t above fire surface fit)
_ATo = difference betweeq a m b i e n t t e m n e r a t u r e at the ceiling a n d
~ m b i e n t t e m p e r a t u r e at t h e level of the fire surface
Bv increasing t h e n u m b e r of e x h a u s t inlets, t h e velocity at each
exha~s~ inlet ~;gvld be reduced. T h e h i g h e s t efficiency fqr t h e
ohvsical m o d f l e x h a u s t System was o b t a i n e d if t h e inlet velocity w ~
iimited go 10 m / s e c or less. It is also r e c o m m e n d e d t h a t t h e ratio
of the s m o k e laver d e p t h to the d i a m e t e r of t h e e x h a u s t inlet (d/D)
be greater t h a n 2 (for-rectan~alar e x h a u s t inlets, use D = 2ab/(a+b).
w h e r e a a n d h are t h e l e n g t h - a n d width o f t h e e x h a u s t o n e n i n g . L
Alternativelv. an expression is provided in t e r m s of t h e a m b i e n t
t ¢ m p e r ~ u r e incr¢~lse frgl B floor to ceiling, which is_lust sufficient
tO p r e v e n t a p l u m e o f h e a t release. O~. f r o m r e a c h i n g a ceiling of
Finally. ~ a third plternative, t h e m a x i m u m ceiling clearance to
wlaich a n l u m e of stren~_h. O~. can rise for a # v e n A.T,.2 follows f r o m
rewriting t h e above e o u a t i o n :
Existing A-3-5 r e m a i n s u n c h a n g e d .
Existing A-3-6 r e m a i n s u n c h a n g e d .
Existing #.-3-6.2.2 r e m a i n s u n c h a n g e d .
Existing A-3-6.2.4 r e m a i n s u n c h a n g e d .
Delete existing A-3-7.1.5.
, ~ : ~-~"-q-~-~-":*:;:~
"A{~,_
~,,:.,_
system. T h e considerations o u t l i n e d in this section are i m p o r t a n t
w h e n d e a l i n g with system in which t h e desima r e o u i r e m e n t - f o r t h e
clear h e i g h t is lust below t h e e x h a u s t inlet lleight[
25
T=5oc
.......... T = I0°C
/
- -,,//(
T=25°C
20
T=50°C
i://__
75 °C
T = IO0 °C
T= 125:0
////
///
.-;~)//
/
//77
./"
T =
.o.9
At equilibrium, t h e h e i g h t z in Eouation (8/ is t h e location of t h e
s m o k e laver interface above t h e fuel level (see Ficure 1-41. The
transition zone is located below this level. For an efficient s m o k e
m a n a g e m e n t system, the d e n t h of t h e transition zone is
a n n r o x i m a t e l v 10% of t h e a t r i u m height. In t h e transition zone. t h e
tglnpera~re a n d 9 t h e r s m o k e p a r a m e t e r s decrease linearly with
h e i g h t between t h e s m o k e laver interface h e i g h t a n d t h e lower edge
of the transition zone.
15
T = 150 C
•' / . . ' /
_= 10
/)2//
f'fJ,
"~'°//"
o
>
E
E
..n/~/.'~/', "
.-
5
0
Existing A-3-7.2.1 r e m a i n s u n c h a n g e d . R e n u m b e r as A-3-8.2.1.
f*
,
,.-:-",
o" ~"
S
"
...
...... -
. . . .
1
/
-
2
Smoke depth (m)
A-3-9 T h e e o u a t i o n s for Dlugholing were originally developed for
I~i~tural vents l T h o m a s . P.H-. Hinc-klev P.L..-Theohald. C~R. a n d
Sims. D.L., Investigations into t h e flow of h o t gases in r o o f venting.
Fire Research Technical P a n e r No. 7. HMSO. L o n d o n . 1963.1 Ith a s also b e e n aDnlied to m e c h a n i c a l s m o k e e x h a u s t system by
Hincklev (62). -'i'he n u m e r i c a l factors i n c l u d e d in Eouations (19
a s s u m e t h e e x h a u s t inlets ;~re located n e a r a wall. Larger
factors can be u s e d if t h e inlets are located n e a r t h e center of t h e
s m o k e reservoir [Sce & c t i ~ s 2.8 and 1.5 for Eauations (19 a~d 20).
r esbectivel~ 1.
Figure A-3-9.
A-3-10 Densit7 of s m o k e is a p p r o x i m a t e l y equal to t h e density of
air. T h e denstty of air at 68°F at sea level isO.075 l b / f t s. T h e density
of air at a n o t h e r t e m p e r a t u r e can be calculated from:
637
NFPA 92B -- MAY 2000 ROP
P/P0
=
L-" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
528/(460 + T)
Z" . . . . . . . . . . . . . . . . . . . . . . . .
•~=cr r r - g ~ t ~ a ; ' c t c c c n v c ~ " n f c r : ' n . a ' 2 c : f r c m t.hc~c tab!c= i n t c "~hc
fc:~,, r e q u i r z d ~)" c q u = f i o n : F r c z c n t c d c ! : c w ~ c r z i n ~ i ~ d o c u m e n t .
where:
P0 = 0 . 0 7 5 ( l b / f t a)
p = density of smoke at temperature
T = temperature of smoke (°F)
T h e ~'.=rn!ng r a t e e f .'x..ateri~= c ~ ' : b e r e l a t e d t c t.he h e a t r e ! t r e e
~ ' ^ o f m a = c r i a ! : ~) . . . . t . : ~ . . . _ _ ,t. . . . . .
~. . . . . . .
t,.. ,~.^ ^~w^_,:..^
( l b / f t s)
g ! ; ' e n a~ a n e ~ e r g 7 r c ! e ~ e r a t e t- . . . . . . . . . . . . . . . . . . . . . . . . . . . .
o _ 1 . , . ~. . . . . .
t ....
d = L a r ~ _ r..^~, t . . . ~ : _ ~ in L . ~ z
A-44.5 Verification devices can include th¢ following:
(1) E n d - t o - e n d v e r i f i c a t i o n o f t h e w i r i n g , e o u i D m e n t , a n d d e v i c e s
in a manner that includes nrovision for nositive confirmation of
~qtivation. periodic te, ting. and manual override operation
.{2) T h e o r e s e n c e o f o n e r a t i n g D o w e r d o w n s t r e a m o f all c i r c u i t
disconnec~
- { 3) Positive c o n f i r m a t i o n o f f a n a c t i v a t i o n b v m e a n s o f d u g ~
o r e s s u r e , a i r f l o w , o r e o u i v a l e n t s e n s o r s t h a t r e s n o n d to loss 9 f
o p e r a t i n g Dower. n r o b i e m s i n t h e D o w e r o r c o n t r o l c i r c u i t w i r i n g .
ai-rflow r ~ t r i c t i o n s , a n d f a i l u r e o f t h e belt. s h a f t c o u D l i n g , o r t n o t o r
r~A1
Annendix B Predicting the Rate of Heat Release of Fires
B-I Introduction. The following presents technioues for
e s t i m a t i n g t h e h e a t r e l e a s e r a t e o f v a r i o u s f u e l a r r a y s likely t o b e
p r e s e n t i n b u i l d i n g s w h e r e ~ m o k e v e n t i n g is a p o t e n t i a l f i r e safety.
p r o v i s i o n . It p r i m a r i l y a~ldresses t h e e s t i m a ! i Q n o f f u e l
c o n c e n t r a t i o n s f o u n d i n r e t a i l , s t a d i a , o f f i c e itIlO s i m i l a r l o c a t i o I l s
t h a t m a v involve l a r g e a r e a s a d d r e s s e d b v t h i s g u i d e . C o n v e r s e l y ,
N F P A 204. Guide for Smoke and Heat Venting. a d d r e s s e s t h e t w e s o f
fuel arrays more common to storage and manufacturing location
and other woes of building situations covered bv that standard.
N F P A 9 2 B is a n o l i c a b l e t o s i t u a t i o n s w h e r e t h e h o t l a v e r d o e s u g ~
e
- - " " ~.
.
"
"
"s
"
•
•
.~::#.~
" "
"
w e e
""
e
" v v
':':
"
"s
"v -- "
(4) Positive c o n f i r m a t i o n o f d a m n e r o p e r a t i o n b v c o n t a c t ,
o r o x i m i t v , o r e o u i v a l e n t s e n s o r s t h a t r e s p Q I l d t o loss o f o p e r a , p c
D o w e r o r c o m o r e s s e d a i r . n r o b l e m s in t h e Dower. c o n t r o l c i r c u i t ,
o r p n e u m a t i c lines, a n d f a i l u r e o f t h e d a m n e r a c t u a t o r , l i n k a g e , OF
damoer itself
(5)- P e r i o d i c a c c e n t a n c e t e s t i n g i n a c c o r d a n c e w i t h C h a p t e r ~
(6)
O t h e r d e v i c e s o r m e a n s as a p p r o D r i a t e
I t e m s ( l ) t h r o u g h (5) d e s c r i b e m u l t i o l e m e t h o d s t h a t m a y b e
u s e d . e i t h e r s i n g l y o r in c o m b i n a t i o n , to v e r i f y t h a t all p o r f i o r l $ o f
~,.~x~
~
~ _. _ . _ _ - "." - -. o "
_-..^_
_ _ __.._, _ . _~~. : . . _ce .a_._
"
the controls and equipment are ooerational. For examnle.
conventional (electrical) supervision may be used to verify the
integrity of the conductors from a fire alarm system control unit to
"
Lhe r- e l a "y c o n t a c t w ' ~thm
~ f e e t o f t h e c o n t r o l s y"s t e m i• n o u t (see 2VFPA¢!:.
~4:';:~.~. . . .(.1 )
~,;~.:.-:-::~- . . . .
72. National Fire Alarm Code °. Section 3-91 ~tld e n d - t o - e n d
~ . ~ .
A c t u ~ : ~ e s t s o t S.lrq[l~r a r r a y s . . . . . . . . .
v "~
"
,
.~
;'
~
,
.
:$k "':','T:.~?._,X~algommms D e r i v e d / r o m tests o I a r r a y s n a w n g s l m n a r tUgl~
e r m c a t l o n m a v De u s e d t o v e n v ¢ o o e r a t l o n t r o m t n e c o n t r o l s y s t e m
.:s~ ,-:.-:-~:.:.--..:.:.:-:.x.:.-.
. .
. . . .
". . . . .
.~ -,.~
- "~-S: .~,'ld ~ i ! ~ n s l o n a l c h a r a c t e r i s t i c s
InPUt to m e cieslre(1 e n a r e s u l t . I t o a t l e r e n t s y s t e m s a r e u s e d . m .
":!~:.~::.::
.....
.
.
.
(4) r , ~ a l c u l a u o n s b a s e d o n t e s t e d DroDertl¢~ a n d m a t e r i a l s a n d
verifv d i f f e r e n t n o r t i o n s o f t h e c o n t r o l c i r c u i t a n d / o r c o ~ i i : :
%
::
- •
•
..:.'.: •
~--:-:'~
5gkex~eg~¢d f l a m e f l u x
e q u i p m e n t , t h e n e a c h s y s t e m w o u l d b e r e s p o n s i b l e for~z'fildicatlt~
::.:':i:-~i:~,. . . . . . . . . . . . . .
~- "
-. •
" •
•
.:;:-***:..
:-~.--.
:::~ ~.-'s:::-iOl M a m e m a t l c a l m o o e t s o i n r e s o r e a a a n d a e v e l o n m e n t
o H - n o r m a l c o n c u t l o n s o n its r e s p e c t i v e s e g m e n t .
~a'.-:.-.'~:.-:i~.¢:.~:: ~ : .
..:::.,::::..
.
.
.
.
""-'~.".-'."t-~.::.
# ::~ ":~:~a~.::-:~t-:'::
~ : :
B-$ A c t u a l T e s t s o f t h e A r r a y. I n v o l v e d • W h e r e a n a c t u a l c a l o r i f i c
E n d - t o - e n d v e r i f i c a t i o n , as d e s c r i b e d in s e c t i o n A , * a , ~ . m o n f f ~ : , b o t h "'"
the electrical and mechanical components o~-~ontr~l~ii!J.!k.::.-':.'~
t e s t o f t h e SDecific a r r a y u n d e r c o n s i d e r a t i o n h a s b e e n c o n d u c t e d
system. End-to-end verification nrovides on'rive con~tion
~t
a n d t h e d a t a is in a f o r m t h a t c a n b e e x p r e s s e d as r a t e o f h e a t
the desired result has been achieved d u ~ e
time tha~
"*:
r e l e a s e , t h e d a t a c a n t h e n b e u s e d as i n p u t f o r t h e m e t h o d s i n t h i s
c o n t r o l l e d d e v i c e is a c t i v a t e d . T h e i n t e n t t ) ~ : ~ t o - e n d
v~ification
guide. Since actual test data seldom produces the steady state
g o e s b e v o n d d e t e r m i n i n g w h e t h e r a c i r c u i t fatl~z-i~sts. ~
instead
assumed for a limited-~rowth fire or the souare of time ~rowth
w hh ee tt hh ee rr tt hh ee dd ee ss il rr ee dd ee nn dd rr ee ss uu ll tt fi.e.
(i.e. aa ii ~~ .d:a~m n e r d a m D e r
a s s u m e d f o r a c o n t i n u o u s - g r o w t h ( t - s q u a r e d ) fire. e n ~ n e e r i n ~
a~ scceer rt at ai ni ns s w
J u d g e m e n t is u s u a l l y n e e d e d t o d e r i v e t h e a c t u a l i n o u t n e c e s s a r v if
p o s i t i o n ) is a c h i e v e d . T r u e e n d - t o - e n d verification~'.-"~erefore~
e i t h e r o f t h e s e a n n r o a c h e s a r e u s e d . ( S e e A o o e n d i x C f o r furtJaer
reaulres a comnarison of the desired oneration to ~e actual end
d e t a i l s r e l e v a n t t o t - s a u a r e d fires.) I f a c o m p u t e r m o d e l t h a t is
result.
a b l e to r e s p o n d t o a r a t e o f h e a t r e l e a s e ver~ns t i m e c u r v e is u s e d .
t h e d a t a c a n b e u s e d d i r e c d v . C u r r e n t l y t h e r e is n o e s t a b l i s h e c l
A n " o p e n " in a c o n t r o l wire. f a i l u r e o f a f a n belt. d i s c o n n e c t i g n 0 f
c a t a l o ~ o f tests o f s n e c i f i c a r r a y s . S o m e t e s t d a t a c a n b e f o u n d in
a s h a f t CouDling. b l o c k a ~ e o f a n a i r tilter, f a i l u r e o f a m o t o r , o r
t e c h n i c a l r e n o r t s . A l t e r n a t i v e l v . i n d i v i d u a l tests c a n b e c o n d u c t e d ,
other abnormal condition which could Drevent Droner operad~,
is n o t e x p e c t e d t o r e s u l t in a n o f f - n o r n ~ l i n d i c a t i o n w h e n t h e
c o n t r o l l e d d e v i c e is n o t a c t i v a t e d , s i n c e t h e m e a s u r e d r e s u l t a t t h a t
t i m e m a t c h e s t h e e x n e c t e d result. If a c 0 p d i t i o n t h a t p r e v e q t s
D r o n e r o D e r a t i o n Derslsts d u r i n g t h e n e x t a t t e m p t e d a c t i v a t i o n o f
the-device, an off-normal indication should be provided.
M a n v fire tests d o n o t i n c l u d e a d i r e c t m e a s u r e m e n t o f r a t e 9 f
h e a t r e l e a s e . In s o m e cases, it c a n b e d e r i v e d b a s e d o n
m e a s u r e m e n t o f m a s s loss r a t e u s i n g t h e f o l l o w i n a e a u a t i o n :
Q = mhc
E x i s t i n g A-5-3.6.2 r e m a i n s u n c h a n g e d .
AFFcaa-:.x ~-. H e a t R : ! : . ~ c
,v~:.
..I . . . . .
~ . . . .
,t I . . , ~
a:_
2~
: . . . . . . . . . .
~--.I~..I^4
;^.
,,r
. . . . . . . . .
;--1"^---~2^---I
( O = r a t e o f h e a t r e l e a s e in kW. 3= d e n s i t y in k g / s . h c = h e a t o f
c o m b u s t i o n in k l / k g )
Rate ~a'~
~ , :
~.,~z..
. . . .
. . . . . .
t
(~-1)
,L:.
-.--'~rw'?
I.,
In o t h e r cases it c a n b e d e r i v e d b a s e d o n m e a s u r e m e n t
h e i g h t as follows:
Q = 3 7 ( / , + 1.02 D) 5/~
. . . . . . . c._^
"~^':-~o
. . . . T ~ c f c ! ! c ; ; ' i n g *.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
of flame
(B-~)
( O = r a t e o f h e a t r e l e a s e in kW. L = f l a m e h e i g h t in m . D = f i r e
d i a m e t e r in m )
638
NFPA
92B ~
MAY 2000 ROP
B-4 Actual Tests o f Arrays Similar to that Involvggt, Where an
actual calorific test of the soecific arrav u n d e r consideration cannot
be found, it may be possible to find data on one or m o r e tests tha~
are similar to the fuel of concern in imnortant matt¢l~ such as ~/pe
of fuel. arrangement, or i~nition scenario. The morg the act~lai
tests are similar to the fuei of concern, the hi~her the confidence
that can be olaced in the derived rate of heat-release. T h e additiq[i
of engineeri-n¢ iudmnent, however, may be n e e d e d to adjust the test
data t-o that at~t)roximating the fuel of concern. If rate of heat
release has not been direcdv measured, it can be estimated using
the m e t h o d described for estimating burnin~ rate from flame
height in Section B-3.
Delete existing Table B-1.
11-5 Ahtorithms Derived from Tests of Arrays Havin~ Similar
Fuels and Dimensional Cb~acteristics.
!]-5.2 O t h e r Normalized Data. O t h e r data based on b u r n i n g rate
per unit area in test~ have been ~eveloped. "gables B-5.2{~) ~md
B-5.2(b) list the most available of these dam.
m"=
,, ~
-kBDx
m ott-e
)
T h e variables 5 for eouation B-3 are as shown in Table B-5.1
lBabrauskas 19951.
The mass rates derived from eouation B-3 are converted ~9 rates
of heat release nsin~ eouation B21. and the h o t of c o m b u , t j o n
from the Table B-5.1. ~'he rate of heat relea#¢ p e r unit area times
the area of the oool fields heat release data for the a n t d n a t e d fire.
B-5.1 Pool Fires. In manv cases, the rate of heat release of a tested
array has been divided by a c o m m o n dimension, such as occuoied
floor area. to derive a normalized rate of heat releas¢ per unit area,
T h e rate of heat release of oool fires is the best d o c u m e n t e d and
accented algorithm in thi~ class.
An eouation for the mass release rate from a nool fire is as
follows- [Balprauskas 199~];
Mateml
_C~'og~ics*
4.4
29_Q~
LPG (mostly C:_H~_
Alcohols
metl-anol ( C H . O H ~
1.9
H
__maaol_~/a~la3_
Simnle ortranic fuels
A
~ -~ x- n z e n ~ f f ~ . ".'~:.
-,.:~..:~
_ _ _ Z L C ~ - - - - f f ~ " ~!i~.::..
'~."-:~
:...'~. ~-~
:"~~ 41
17.00o
19.000
0.017
0.00S~*
0.015
_____~ xan~ J_C_~lt~)_
65
11.000
diethvl e t h e r ( C:_Hx0_O_)_
Petroleum p r o d u c t s
benzine
___.ga~liae
kerosine
___j2=~
~_d£-5
warts former oil.
45
14.500
0.017
0.21
46
46
51
47
51
47
19.000
19.000
18.500
18.500
18.500
20.000
O.0O98
0.011
0.008
0.01
0.011
0.008**
1.1
0.64
1.1
1.1
0.49
59B 6_~
~l~
17.000
18.000
0.0072
0.O045
B0.0092
So ~IL4L
___p_Q lymet hyimet bacrvtat e
74
10.000
0.0041
___~t~ro~u
56
18.500
0.00~7
66
17.000
0.007
h~.rocarbon
fuel
oil. h c_~.w~_
crude oi!_
~__Lc~
_____~lystyrene ( C. I:~.~
(B-3)
*Fog_gools on cky land. n g t over water.
**E~fi mate unc er lain sin ce o n l x l ~ d ; ~ . ~ 4 a o i n ~ a~U able.
HValue i n ~ e n d e n t of diam eter in turlml ent regime.
639
1.0
NFPA 92B -- MAY 2000 ROP
Table B-5.2(a) Unit Heat Release Rate for Commodities
Heat release rate per unit floor area of fully involved combustibles, based on
negligible radiative feedback from the surroundings and 100 percent combustion
efficiency.
Btu/sec°fC of
Floor Area
Commodity
Wood pallets, stacked 11/2 ft high (6-12% moisture)
125
Wood pallets, stacked 5 ft high (6-12% moisture)
350
Wood pallets, stacked 10 ft high (6-12% moisture)
600
Wood pallets, stacked 16 ft high (6-12% moisture)
900
Mail bags, filled, stored 5 ft high
35
Cartons, compartmented, stacked 15 ft high
150
PE letter trays, filled, stacked 5 ft high on cart
750
PE trash barrels in cartons, stacked 15 ft high
175
PE fiberglass shower stalls in cartons, stacked
125
15 ft high
PE bottles packed in Item 6
550
PE bottles in cartons, stacked 15 ft high
175
PU insulation board, rigid foam, stacked 15 ft high
170
PS jars packed in Item 6
1,250
PS tubs nested in cartons, stacked 14 ft high
475
PS toy parts in cartons, stacked 15 ft high
180
PS insulation board, rigid foam, stacked 14 ft high
~
PVC bottles packed in Item 6
PP tubs packed in Item 6
.4# ~ 5 - PP & PE film in rolls, stacked 14 ft high
~'~g
550
Methyl alcohol
... ~t,.~, "
Gasoline
~
6 ~g'"
Kerosene
Diesel oil
P ~
a " ~ e
1~
Note:
PE ffi Polyethylene
q~
PS = Polystyrene
PU ~'~,~
PV = Polyvinyl chloride
%
Table
~-~
-'::i..':~-.~?~..
~::.-.'-x::: ".:.:.:-:.:Y:~~' !~::!':
.,.:-::maximum heat r e l e ~ r a t e (F ~ .
g.:,:.Y:"
Qm
q
= heat release d e n s i t ~ e c /
: ) ":.~.:-'~.
A
= floor area (ft2)
'%~!!~.,..
-~-.-.::.) ~..-".~
The following beat release rates per ~ . . ~ o r area are for fully involved combustibles, assuming 100
percent efficiency. The growth times she ffi are those required to exceed 1000 Btu/sec heat release rate for
developing fires assuming 100 percent mbustion efficiency.
(PE = polyethylene; PS = polystyrene; PVC = polyvinyl chloride; PP = polypropylene; PU ffi polyurethane; FRP
= fiberglass-reinforced polyester.)
where:
Warehouse Materials
Classification
Wood pallets, stacked 1 1/2 ft high (6-12% moisture)
Wood pallets, stacked 5 ft high (6-12% moisture)
Wood pallets, stacked 10 ft high (6-12% moisture)
Wood pallets, stacked 16 ft high (6-12% moisture)
Mail bags, filled, stored 5 ft high
Cartons, compartmented, stacked 15 ft high
Paper, vertical rolls, stacked 20 ft high
Cotton (also PE, PE/Cot, Acrylic/Nylon/PE),
garments in 12-ft high rack
Cartons on pallets, rack storage, 15-30 ft high
Paper products, densely packed in cartons, rack
storage, 20 ft high
PE letter trays, filled, stacked 5 ft high on cart
PE trash barrels in cartons stacked 15 ft high
FRP shower stalls in cartons, stacked 15 ft high
PE bottles packed in Item 6
PE bottles in cartons, stacked 15 ft high
Growth
Time
(sec)
150-310
90-190
80-110
75-105
190
6O
15-28
2O-42
Heat
Release
Density (q)
110
330
600
900
35
2OO
40-280
470
190
55
85
85
75
640
(s-slow)
(m-medium)
(f-fast)
m-f
f
f
f
f
m-f
m.-~
750
250
110
550
170
f
w
N F P A 92]8 - - MAY 2 0 0 0 R O P
Wa.ho..
I
leon, ued?
Growth
Time
PE pallets, stacked 3 ft high
PE pallets, stacked 6-8 ft high
PU mattress, single, horizontal
PF insulation, board, rigid foam, stacked 15 ft high
PSjars packed in Item 6
PS tubs nested in cartons, stacked 14 ft high
PS toy parts in cartons, stacked 15 ft high
PS insulation board, rigid, stacked 14 ft high
PVC bottles packed in I t e m 6
PP robs packed in Item 6
PP and PE film in rolls, stacked 14 ft high
Distilled spirits in barrels, stacked20 ft high
Methyl alcohol
Gasoline
Kerosene
Diesel Oil
* Hre growth rate exceeds classification criteria.
For SI Units: 1 ft = 0A~05 m.
n~t
Classification
(xiow)
(m-medlum)
ff-f.a)
1~o
30.55
110
f
.
f
lio
8
55
105
110
7
s
f
f
9
10
40
2.g.40
~0
r;
°
÷
B-5.S Other Useful Data. There are other d a ~ that are no t
normalized that mkrht be useful in develooing the rate of h~ut
release curve. Examnles are-included in the Tables B-5.3(a)
thromrh B-5.$Ch),
Table B-5.S(a) Maximum Heat Release Retea from
(Stu/sec~
Medium wastebasket with milk cartons
Large barrel with milk canons
Upholstered chair with"polyurethane foam
Latex foam mattress (heat at room door)
100
140
550
1200
Table i
Ilura
Flame
m~
Heat
Flux
Cigarette 1.1 g (not
puffed, laid o n solid
surface), bone dry,
conditioned to 50%
v "q~
W
R,H.
,~
Methenamine pill, 0.15 g
Match, wooden (laid
o n solid surface)
Wood cribs, BS 5852
Part2
No. 4 crib, 8.5 g
No. 5 crib, 17 g
No. 6 crib, 60 g
No. 7 crib, 126g
Crumpled brown lunch bag, 6 g
Crumpled wax paper, 4.5 g (tight)
Crumpled wax paper, 4.5 g (loose)
Folded double-sheet newspaper, 2"2 g (bottom ignition)
Crumpled double-sheet newspaper, 22 g (top ignition)
Crumpleddouble-sheet newspaper, 22 g (bottom ignition)
Polyethylene waste-basket, 285 g, filled with 12 milk cartons (~90 g)
Plastic trash bags,
filled with cellulosic
0.2-14 k0e
Time duration of significant flaming
b Total b u m time in excess of 1800 sec
¢ As measured on simulation b u r n e r
d Measured fi'om 25 m m away
e ResUlts vary greatly with packing density
1 in, = 25.4 m m
1 Btu/sec = 1.055 W
1 oz = 0.02835 kg = 28.$5 g
I B m / f t ~sec = 11.$5 k W / m
2
2
641
5
1~0
5
45
80
1200
gO
20-S0
IOO0
1900
20OO
0400
1200
1800
550O
40O0
74O0
17,000 .
50,000
120,000
to
~50,000
190
200
42
.
14
~5
4
18-20
15d
17d
20d
190
~0
8O
25
20
100
4O
20
200b
200b
550
200
35c
N F P A 92B - - M A Y 2 0 0 0 R O P
Existing Table B-6 remains unchanged. Renumbered as Table
B-5-$(c).
Existing Table B-7 remains unchanged. Renumbered as Table
B-5-B(d).
Table B-5-3(e) Effect of Fabric Type on Heat Release Rate in Table B-5-3(a)
(within each i~roup all other construction features were kept constant) [3]
Full-Scale
Peak q
Specimen
(kW)
Paddinlg
Fabric
Group 1
F24
700
cotton (750 g / m ~
FR PU foam
F21
1970
polyolefin (560 g/m ~)
FR PU foam
Group 2
F22
$70
cotton (750 g / m ~)
cotton batting
F23
700
polyolefin (560 g / m ~)
cotton batting
Gr~p 3
28
none
FR PU foam
17
530
cotton (650 g / m ~)
FR PU foam
21
900
cotton (110 g / m ~)
FR PU foam
14
1020
polyolefin (650 g / m ~)
FR PU foam
7, 19
1340
pol)'olefin (360 I~/m~/
FR PU foam
1 Ib/ft~ = 48.83 g / m z
1 oz/fF = 305 g / m ~
~!~
1 Btu/sec = 1.055 kW
.¢~
'\'~
Table B-5.3(f) Effect of Padding Type on Maxim
(within each trrouo all other construction
Specimen
F21
F23
F21
F25
F24
F22
12, 27
7, 19
15
Rate i~"Table B-5.3(d)
~t constant) [3]
Peak q
'¢~ ,x
(kW~
":g~:",~%%~.
L : :,a.~d=d in
":~'.
Fabric
Group 1
~ .
4~.-"'
1970
FR'~J~,~~$~"
polyolefin (560 g / m ~)
1990
N ~'~~'+
polyolefin (560 g / m ~)
Group [ ~".'::.
197~)ff ~=~'~:~i~iFR P~i~'o~i
o..~n "
polyolefin (560 g / m 2)
~.~,~,
~" cotton':~ling
polyolefin (560 g / m 2)
70(
~-.~
~
" 1 ~ ' foam
~ . . . . c o t t o n batting
.-::'!::
1" ~,
~..._
1540~
': "::!%.-:-:-.:ii~.-. 120 :~ i'
%'%6rou~1
%.:.~:...:.x.
20
% ~ . . f f .,~
17
"~..~:g~
22
.~-i~
~: 3
1 lb/fi~ = 48.83 g/m ~
1 oz/fF = 305 g / m ~
1 Btu/sec = 1.055 kW
~'. l~r~ PU foam
:U FR PU foam
neoprene foam
NFR PU foam
FR PU foam
neoprene foam
Table B-5.B(g) Effect of Frame Material for Specimens with NFR
PU Padding and Pol),olefin Fabrics [3]
Mass
Peak q
Specimen
(k~)
(kW)
Frame
F25
27.8
1990
wood
FS0
25.2
1060
polyurethane
F29
14.0
1950
pol):prop]:lene
1 lb = 0.4556 kg
1 Btu/sec = 1.055 kW
642
cotton (750 g/m ~)
cotton (750 g/m ~)
polyolefin (360 g/m ~)
polyolefin ($60 g / m ~)
polyolefin (360 g / m ~)
cotton (650 g/m ~)
cotton (650 g/m~!
cotton (650 ~[/m
NFPA 92B ~ MAY 2000 ROP
~-6.2 Discussion o f M e a s u r e d Prooerties. Table B-6.2 lists
th¢ type o f fire nrooerties obtainab]e f r o m t h e cone or
F~gtory Mutual-calorimeters a n d similar i n s t r u m e n t s .
Table B-5.3(h) Considerations for Selecting Heat Release Rates for
Design
C o n s t a n t Heat Release Rate Fires
Theobald
(approx. 26
(industrial)
260 k W / m ~
Btu/sec-ft 2 )
Law
(approx. 29
(offices)
290 k W / m ~
Btu/sec-ft 2 )
Hansell & M o r g a n
(approx. 25
(hotel r o o m s )
249 k W / m ~
Btu/sec-ft 2)
Variable H e a t Release Rate Fires
NBSIR 88-3695
Fire Growth
Fuel Configuration
C o m p u t e r Work Statiot~
free b u r n
compartment
Shelf Storage
free b u r n
Rate
In Table B-6.2, t h e rate of h e a t release (RHR). m a s s loss.
a n d time to imaition are f u n c t i o n s of t h e externally aDolied
iBcident vadi~mt h e a t flux i m n o s e d o n t h e tested samt~le.
T h e p u r p o s e of t h e externally applied flux is to simulate t h e
fire e n v i r o n m e n t s u r r o u n d i n g a b u r n i n g item. In general, it
can be estimated t h a t a f r e e - b u r n i n g fuel package (i.e.. o n e
that b u r n s in t h e o o e n a n d is n o t a~ected-bv e n e r a v feedback
f r o m a h o t gas laver of a h e a t source o t h e r t h a n its own
flame) is i m n a c t e d by a flux in t h e r a n g e of 95 k W / n l ~ 1;o 50
k W / m ~. If t h e fire is in a space a n d conditioq~ are
a o o r o a c h i n g flashover, this can increase to t h e r a n g e of 50
k~0)/m ~ to 75 k W / m ~. In fully developed. Dost-flashover fires.
a r a n g e o f 75 k W / m 2 to over 100 k W / ' m ~ can be exoected.
T h e (ollowing is a discussion of t h e individual orooerties
m e a s u r e d or derived a n d t h e usual f o r m u s e d to report t h e
slow-fast
very slow
Office Module
m e d i u m u p to 200 sec,
fast after 200 sec
very slow-medium
NISTIR 483
Fuel Commodity
Peak Heat Release
Rate (kW)
C o m p u t e r Work Station
1000-1300
Fuel C o m m o d i t y
Chairs
Loveseats
Sofa
Rate of Heat Release. Rate of h e a t release is d e t e r m i n e d
ta)
NRS Monograph 173
Peak Heat Release (kW)
80-2480 (<10, metal frame)
940-2890 (370, metal frame)
3120
il-6 Calculated Fire Descriotion Based on Tested Propertie#,
B-6.1 Background. It is nossible to m a k e general estimates of the
rate of heat-release o f b u r n i n ~ materials based o n t h e fire
properties of that material. T h e fire nrooerties involved can l~er
d e t e r m i n e d bv small-scale tests. T h e m o s t i m o o r t a n t of these tests
are calorimeter tests involving b o t h oxv~en d e p l e t i o n calorinaetry
a n d t h e application of extern-al h e a t flUX to t h e sample while
d e t e r m i n i n ~ time to ignition, rate of mass release, a n d rate of h e a t
L J
,#!
:..-.~ . ~
6~ 1200
"~:" 1000
Products Usin
8oo
6oo
11
0 kW/m a . . . . 2S kW/m 2 ........ 50
,
/,,,
l
!_.
~ "~
;
]|
400
oi/J
!
200
~
400
600
~
800
1000
Time (sac)
-.
1200
,..
1400
1600
Figure B-6-2(a) Typical ~raphic o u t o u t o f c o n e calorimeter test,
nroDertv test data as t h e basis of an analvtlcal evaluation of t h e rate
of h e a t release involved in the use o f a tested material. T h e
a p p r o a c h o u t l i n e d in this section is based on that pl'esented bY
Nelson a n d Forssell [19941.
T a b l e B-6.2 Relation o f Calorlmeter-Measured Pronerties to Fire Analwi~
lgatfiaa
~ame
Rate of h e a t release H
xxx
Mass loss H
T i m e to ignition H
xxx
xxx
Effective t h e r m a l oroDerties*
xxx
xxx
Heat of combustion*xxx
Heat o f gasification*
Critical imaition flux*
xxx
xxx
Ignition t e m p . *
xxx
xxx
H-Pronertv is a f u n c t i o n of t h e externally anolied incident flux,
* Derived Drooerties f r o m calorimeter m e a s u r e m e n t s .
643
xxx
xxx
xxx
xxx
NFPA 92B ~
MAY 2000 ROP
Often only the neak rate of heat release at a snecific flux is
renorted. Table B-6.2(a) is an examole.
]'able B-6.2¢a) Average Maximum Heat Release P-~tes t k W / m ~)
Material
PMMA
Pine
Sample A
Sample B
Sample C
Sample D
2.2 B t u / s / f t ~
Exposinl{ Flux
Orientation
Horizontal
Vertical
Horizontal
Vertical
Horizontal
Vertical
Horizontal
Vertical
Horizontal
Vertical
Horizontal
Vertical
4.4
Btu/s/ft ~
Exposing Flux
6.6 B t u / s / f t 2
Exposing Flux
79
63
21
15
18
11
15
18
19
15
114
114
23
56
22
19
21
29
22
15
11
11
57
49
12
11
11
8
12
5.~
6.2
(a) Thermally Thin Materials. Relative to i~nition f r o m a constant
incident h e a t flux. hi. at the exnosed surface a n d with relatively
(b) Mass Loss Rate (m). Mass loss rate is determined by a load
~;~lJ: The m e t h g d of reoortin~ is identical to that for rate'of heat
release. In the tvoical situation whene the material has a consistent
h~gt of combustion, the curves for mass loss rate a n d rate of heat
release are similar in shane.
(c) Time to Ignition (aA. Time to imaition is r e n o r t e d for each
individual test a n d am~l]'ed flux level conducted.
(d) Effective Thermal Inertia (kDc). Effective thermal inertia is a
m e a s u r e m e n t of the heat rise resnonse of the tested material to the
heat flux imDosed on the sample. It is derived at the time of
ignition and is based on the ratio of the actual incident flux to the
(ritical ignition flux and the time to ignition. A series of tests at
different levels of applied flux is necessary, to derive the effective
thermal inertia. Effective thermal inerda derived in this m a n n e r
(B-5)
The time to i~nition of a thgrmallv thin material subiected to
iIlddent flux alaqve a critical incident flux is;
tig = p c l
paa~
~
(h) Ignition Temberature (T.I. Ignition temperature is the surface
t e m p e r a t u r e of a satanic at which flame occurs. This is a samole
material value that is indeDendent of the incident flux. It i~
clcrivable from the calorimeter tests, the LIFT aonaratus test. arid
o t h e r tests. It is derived from the time to imaite in a given test. the
aoolied flux in that test. and the effective thermal inertia of the
samole. It is renorted at a single temoerature. If the te~, jIl¢lqclCS
a nilot flame or snark, the reported tempera~ture is for niloted
imaition: if there is no nilot nresent, the temoerature is-for
autoignition. Most available data is for piloted ignition.
.
v
.
. ~ -
v
B
T~ < 0.1(T.:atmi.~...~= 0.1¢T,;B Ta)
(B-7)
Eouation B-7 can be used to show that a material is thermallv
thick I'Carslaw and lae~er 19591 if:
1 > 2 ( t 10) ]/2
(B-8)
For example, according to e a u a t i o n B-8. in the case of ~m ignidon
test on a slaeet of m a o l e o r oal~ wood. if fig = 35 s is measurecl in a
niloted itmition tesL then. if the samnle thickness is trreater than
anoroximatelv 0.0042 m. the u n e x o o s e d surface of tl~e sample can
be exoected to be relatively close to T_ at t = t, and the satanic i~
considered to be thermally thick.
B-6,3 Ignition. Eouations for time tO ignition, t.~ are L,iven for
both thermally thin and thermally thick materials, as defined m B6.3(a) and (b). For materials of intermediate deoth, estimates for
tig necessitate considerations beyond the scqpe of this presetliat,ion
[Drvsdale 1985. Carslaw a n d Iaeger 19591.
-
i It
(b) Thennall~ Thick Materials. Relative to the taroe of iaxaition test
described in B~6.3(a). a satanic of a inaterial of a-thickn¢$s, I, iS
considered to be thermally tfaick if the increase in temperature of
the u n e x n o s e d surface is relatively small c o m n a r e d to that of the
exnosed surface at t = tie. For examole, at t = ti~.
(g) Critical Ignition Flux (a ). Critical ignition flux is the
rnh3imum level-of incident flux on the samnle needed to ignite the
samole gfiven an unlimited time of anolicatJon. At jnciden-t flug
leveis less than the critical ignition flux. ignition does n o t take
v
(T,,-To)
.
Time to ignition of a thermally thick material subjected to
incident flux above a critical incident flux is:
.
644
.,,]2
IB-9)
N F P A 92B ~ MAY 2000 R O P
It s h o u l d be n o t e d t h a t a Darticular material is n o t intyinsicaily
t h e r m a l l y t h i n or th ick (i.e.~ the characteristic of b e i n g t h e r m a l l y
thin or thick is n o t a m a t e r i a l characteristic or propertv) b u t also
d e p e n ~ on the thickness of the p a r t i c u l a r s a m p l e (i,¢,, a p a r t i c u l a r
m aterial can be i m p l e m e n t e d in e i t h e r a t h e r m a l l v thick or
t h e r m a i l v t h i n config uratioll),
Flame s o r e a d is t he m o v e m e n t of t h e fl a me f r o n t across th e
surface of a ma t e ri a l t ha t is b u r n i n g (or e x o o s e d to a n i g n i t i o n
flame) w he re t he e x n o s e d surface is n o t vet fully involvec1.
Phvsicailv. flame s o r e a d can be t r e a t e d as a succession of ig n itio n s
re s ul t i ng from t he h e a t ener~v o r o d u c e d by t he b u r n i n g n o r t i o n of
a mater(al, its flame, a n d a nvot -he r i n c i d e n t h e a t e n e r ~ i m n o s e d
u n o n t he u n b u r n e d surface. Othglr sources of i n c i d e n t e n e r a v
i n c l u d e a n o t h e r b u r n i n g object, h i g h t e m v e r a t u r e trases t h a t c a n
a c c u m u l a t e in t h e u o o e r o o r t i o n o f a n e n c l o s e d soace, a n d t h e
r a d i a n t h e a t sources us e d in a test aoDaratus such as t h e co n e
c a l o r i m e t e r or t h e Lib-q" m e c h a n i s m . For analysis ournoses, f lam e
st)read can be d i v i d e d into two categories, t h a t w h i c h moves in th e
s a me d i r e c t i o n as t h e fl a me ( c o n c u r r e n t or wind-aided flame
s nre a d) a n d t ha t which moves i n a ny o t h e r d i r e c t i o n (lateral or
o n n o s e d flan1~ s o r e a d L C o n c u r r e B t f l a m e s p r e a d is assisted bv th e
i n c i d e n t hea~ flux from t he fl a me to u n i g n i t e d o o r t i o n s o f t h e
b u r n i n g material. Lateral fl a me s o r e a d i s n o t so assisted a n d tends
to be m u c h slower in nrotrression unless a n e xt e rna l source o f h e a t
flux is present. C o n c u r r e n t flam¢ s n r e a d can be e xor es s ed as
(c) Pro~a~'ation Between Sebarate Fuel Packages. W h e r e the
c o n c e r n is (or nronatration I~etween individua] s e o a r a t e d fuel
nackages, incid~en(fiux can be calculated using t r a d i t i o n a l
r a d i a t i o n h e a t transfer o r o c e d u r e s [Tien et al ] 9 9 5 L
T h e rate of r a d i a t i o n h e a t transfer from a f l a m i n g fuel nacka~e of
total energ y release rate. O. to a facing surface e l e m e n t of an
e x p o s e d fuel vacka~re can be esfimatecl from:
qm~"= X~Q/4 Br 2
qme
T!
¢B-lo~
= I n o d e n t flux on e x p o s e d fuel. Xr ffi R a d i a n t fraction of
e x o o s i n g fire. O ffi rate of h e a t release of e x o o s i n g fire. a n d r =
radial distance from c e n t e r of exDosing fire to ex~nosed fuel.
(~i tt L
v=
B-6.4 Estimatin~ Rate of Heat Release. As discussed in B-6.2. tests
have d e m o n s t r a t e d t h a t t h e c n e r w f e e d b a c k from a b u r n i n ~ fuel
p a c k a g e ranges f r o m a n o r o x i m a ( e l v 25 k W / m ~ to 50 k W / m ~. For a
r e a s o n a b l e conservative-analysis, it is r e c o m m e n d e d t h a t test d a t a
d e v e l o n e d with an i n c i d e n t flux of 50 k W / m ~ be used. For a first
o r d e r a n o r o x i m a t i o n , it s h o u l d be a s s u m e d t h a t all of th e surfaces
t h a t can be s i m u l t a n e o u s l y involved in b u r n i n g arc releasi ng e n e r g y
at a rate eoual to t h a t d e t e r m i n e d by testing the material in a fire
o r o n e r t i e s c a l o r i m e t e r with an i n c i d e n t flux of ~iO k W / m ~ for a freeb u r n i n g material a n d 75 k W / m 2 to 100 k W / m ~ for nost-flashover
conditions.
laains u n c h a n g e d .
~ains unchanged.
A p p e n d i x E.
In m a k i n g this estimate, it is necessary to assume t h a t all surfaces
~.y Appendix E Example Problems Illustrating the Use of the
Equations in NFPA 92B
This appendix is not apart of the recommendations of this NFPA
document but is included for informational purposes only.
Given: A t r i u m with u n i f o r m r e c t a n g u l a r cross sectional areaHeight
Area
120 ft
20,000 sq tt
1.4
5000 B t u / s e c
94 ft
A/HA2
D e s i gn Fire (steady state)
H i g h e s t Wa l ki n~ Surface
(B-11~
he
1. D e t e r m i n e t he t i me w h e n t he first i n d i c a t i o n of s m o k e is 6 feet
above t h e h i g h e s t w a l ki ng surfacer,
Th e r e s u l t i n g mass loss rate is t h e n m u l t i n l i e d bv the derived
effective h e a t o f c o m b u s t i o n a n d the b u r n i n g a r e a e x o o s e d to t he
i n c i d e n t flux to n r o d u c e t h e e s t i m a t e d rate of h e a t release as
a. Use E a u a t i o n 9
Q/' = th"hc A.
z/H=O.67-O.281n~Q'/3/H4/3)/(4/H 2 )]
f~-tz)
B-6.5 F l a m e Svread . If it is d e s i r e d to p r e d i c t the ~rowth of fire ~s
it p r o p a g a t e s over c o m b u s t i b l e surfaces, it is necessary to estimate
flame soread. T h e c o m o u t a t i o n of flame s n r e a d rates is an
e m e r g i n g t e c h n o l o g y still in an e m b r y o n i c stage. Predictions
s h o u l d b-e c o n s i d e r e d as o r d e r of m a g n i t u d e estimates.
Z
H
Q
v
1/3)
~ ((4/3)
A/H^2
100ft
120ft
5000 B t u / s e c
17.1
591.9
1.4
0.83 = 0.67 - 0 . 2 8 1 n [ ( 1 7 . 1 t / 5 9 1 . 9 ) / ( 1 . 4 ) l
0.16 = -0.281a[0.03t/1.391
0.10 = -0.281n [0.02tl
645
NFPA
92B
~
MAY
-0.57 = In[0.02tl
2000
ROP
2. D e t e r m i n e t h e volumetric e x h a u s t rate r e q u i r e d to keep s m o k e
5 ft above t h e h i g h e s t walking level in t h e atrium, i.e., n i n t h floor
balcony. Consider t h e fire to be located in t h e c e n t e r o f t h e floor o f
t h e atrium.
With t h e fire located in t h e center o f t h e atrium, a n axisymmetric
p l u m e is expected. First, E q u a t i o n (13) of 3-7.1.2(a) m u s t be
applied to d e t e r m i n e the flame height.
0,56 = 0.02t
t = 28 seconds
b. Use t h e mass flow m e t h o d , based on Eouation 14.
Given:
Q~ = 3500 B t u / s e c
z~ = 0.SSS Q~/5
z 1 0.533 (3500) ~/5
z 1 = 13~9 ft
Two calculation m e t h o d s will be used. T h e first calculation will
a s s u m e a s m o k e density of 0.075 Ib/ft^3. This is eouivalent to
s m o k e at a t e m p e r a t u r e of 70 17. T h e s e c o n d calculation a s s u m e s
t h e l~yer t e m p e r a t u r e is equal to t h e average p l u m e tep~perature at
t h e h e i g h t of the s m o k e laver interface. In both cases, no h e a t loss
f r o m t h e s m o k e laver to t h e a t r i u m b o u n d a r i e s is assumed. A time
interval of 1 s e c o n d is c h o s e n for each case.
With the design interface of the s m o k e layer at 85 ft above floor
level, t h e flame h e i g h t is less t h a n t h e design s m o k e layer height.
Thus, u s i n g E q u a t i o n (14) of 3-7.1.2(b) to d e t e r m i n e t h e s m o k e
p r o d u c t i o n rate at t h e h e i g h t o f t h e s m o k e layer interface:
iA Calfulafion ] - No s m o k e d¢osity corr¢ction
z = 8 5 ft
m = 0.022 O~ l/s z ~/s + 0.0042 Q¢
m = 0.022 (gS00) ~/~ (85) ~/s + 0.0042 (~500)
m = 564 l b / s e c
Steo 1 Calculate m a s s flow (Ib/sec~ at z = H usin~ Fxauation 14.
Step 2 Convert mass flow to v o l u m e flow {ft^3/sec] u s i n g
Eauation 16. a s s u m i n e s m o k e t e m o e r a t u r e is 70 F.
If the s m o k e e x h a u s t rate is equal to t h e s m o k e p r o d u c t i o n rate,
t h e s m o k e layer d e ~ t h will be stabilized at t h e design height. T h u s ,
converting the ~ w
rate to a volumetric flow rate u s i n g
Equation (16).~m 22~.5:
Sten 3 A s s u m e t h e s m o k e volume p r o d u c e d in t h e selected time
ipterval i8 instantly a n d u n i f o r m l y distributed over t h e atrium area.
D e t e r m i n e t h e d e o t h of t h e s m o k e laver, clz frO. deposited d v r i o g
l;he selected time oeriod.
V ~ m/r
Steo 4 Calculate t h e new s m o k e laver interface h e i g h t (fO
R e p e a t steps until t h e s m o k e laver interface reaches t h e design
V ='~.]~f~)r~'ec or 451,260 scfm
Table ~ 1 o f Values illustrates the calculation t e c h n i o u e .
Table E-I
~ d
Valiies
Time (sec~
Vol fft^3/sec~
1
%i!,,
~ . . J 18.0
:..::~:~
7.9_72
f?';:-'-:;:;:;:;:;:;.,
229_~
12847
12D2
~-.:,:.:~,!
114.9
12619
938
125O8
93o
12397
922
12288
914
12181
11s.1
9o6
12O74
10
11
946
112.5
898
.1.£
111.9
890
14
111.3
882
1..55
110.7
875
16
11866
867
11562
86o
Ll_lfifi
17
109.5
18
109.0
852
108.4
845
L1__220
107.9
838
11174
2o
646
NFPA 92B ~
T a b l e E-1
T i m e {sec)
MAY 2000 ROP
Sample Calculated Values (continued)
zffO
Mass
Vol ( f t ^ 3 / s e c ~
[.~'~Y~
11O80
106.7
824
10987
8_1_7.
1O895
810
108O4
8O4
1O715
26
104.0
797
27
104.1
790
~
784
10451
lOZ.O
77'7
lO~66
i12
3o
771
7o5
32
lol.5
759
_3_3_
lOl.O
752
~4
loo.5
746
10115
.~&,.
lOO~Z
.~
fffi"
. . . . . .
.~::".':-"~-"~:~..
~:..~~:-"~"~:'~:?~,'~
.::.
-,'-'i~'#~-.
'-.'~&~.~.~"
3. D e t e r m i n e if t h e p l u m e will contact all of t h e walls prior to
~.~:,
..~ii~:'J':~:.
r e a c h i n g the design h e i g h t n o t e d in #4 (5 ft above the h i g h e s t
w ''~i~
....
walking level).
.
"" % ~ ~ i ~ . . . . . .
•
.+:--IZ
=
~2
2
~.~..:
T h e above calculation in #4 a s s u m e s that t h e s m o k e p l u m e nas
~.:'~!:..::.. ft. l ~ a n - ~ .~.-"
~
n o t widened to contact t h e walls of t h e a t r i u m prior to r e a c h i n g the " ~ . . . - , t v~-::design interface height. This calculation serves as a check.
'!~'~: . # ~ _ ~ " : ' [ ~ H tT T ~ / t T + 460 ~1 a/~
Using Equation (23) f r o m Section 3-8 with an interface h e i g h t of
":.~i,..:.:~'~, - ] ~
t ~ k, , t , " ou,,~ L. . . . . t,~,
85 ft (z = 85 ft)
.,.::#.~g~,~.-'i~::,
":¥;:" V = Z~'~ l t~Z:Z) ( o ) t t v v v - / v J / ~ l v o v + 460)] ~/~
'
.?:-::" "::~!!!!!:
:~i, V = '~Zo I t / m l n
d -_-0.5zf~5,
"
_ -.7." _ ~
ct = 4X.b tt
,:::..'.:~iiiiiiii~::. :~!~:.'.i??~:.:.'.-.:..:'::.:.~:.~:'" (b) For a fire in t h e atrium, d e t e r m i n e t h e o p p o s e d airflow
" "-';i.":':-'.g.-'::-..,-::'
.....
;:: ~::oi~i" r e a u i r e d to restrict s m o k e spread into t h e t e n a n t space.
"~:~.-'.:-:'.'~"
"~:'.-"~::" -
T h u s , the s m o k e does ~aot contact t h e w a l l s . , 6 ~ " : t J ~ : ' ~ p~'.$.@::;;~
r e a c h i n g t h e design interface height.
~.:>...-::':?'
"'"~:::'.~::~.:..:~i:: ~ii~:::'~*
Given:
~=- 5 ^tmO l~tu/s" ec
z 90ft
V = 17 [ O / z ] ~/s
7 [5
01 ~/s
4. D e t e r m i n e the t e m p e r a t u r e of t h e sr~'olt:~i-"::~..e..rafter ( ~ "
ctuatlon
'.:m:::::.
:.-~:
T h e quality of t h e s m o k e c o n t a i n e d in t h e s m o k ~
m i g h t be
i m p o r t a n t in t h e context of tenability or d a m a g e a .hi'fry studies.
Applying Table 3-5:
~=
"
P
Appendix F Referenced
Given:
Publications
O~ = 3500 B t u / s e c
r = 0.075 l b / f t 3
c = 0.24 Btu/lb-°F
V = 7521 ftS/sec
AT = Q J ( p c V )
F-1 T h e following d o c u m e n t s or portions t h e r e o f are r e f e r e n c e d
within this guide for informational p u r p o s e s only a n d are t h u s n o t
considered part of its r e c o m m e n d a t i o n s . T h e edition indicated
here for each reference is t h e c u r r e n t edition as of t h e date o f t h e
NFPA issuance of this guide.
AT = 3500/[ (0.075) (0.24) (7521) ]
17-1.1 N F P A P u b l i c a t i o n s . National Fire Protection.Association, 1
Batterymarch Park, P.O. Box 9101, Quincy, MA 02269-9101.
AT = 26°F
NFPA 13, Standard for the Installation of Sprinkler Systems, 1996
edition.
5 . O n the t e n t h floor, a 10 ft wide × 6 ft h i g h o p e n i n g is desired
from the t e n a n t space into t h e atrium.
(a) For a fire in t h e t e n a n t space, d e t e r m i n e t h e o p p o s e d airflow
r e q u i r e d to contain s m o k e in t h e t e n a n t space (assume fire
t e m p e r a t u r e is 1000°F).
Using Equation (24), 3-10.l:
NFPA 72, National Fire Alarm Code ®, 1996 edition.
F-I.2
647
Other Publications.
NFPA 92B -- MAY 2000 ROP
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