semi
SEMI $6-0707
EHS GUIDELINE FOR EXHAUST VENTILATION OF SEMICONDUCTOR
MANUFACTURING EQUIPMENT
This safety guideline was technically approved by the global Environmental, Health & Safety Committee.
This edition was appl'r.wed for publication by the global Audits and Reviews Subeonnnittee on April 25. 2007.
It was available at www-semi.org in June 2007 and on CD-ROM in July QUOT. Originally published in 1993.
NOTICE: This document was completely rewritten in 2007.
NOTICE' Conformance to the "should" provisions of this guideline is necessary to declare conformance to
this document. Conformance to " m y " , *'suggested-n°', "'preferred"', "recommended", 4.'NOTE", or "Related
Information" provisions is not necessary to declare conformance.
1 Purpose
l . l This safety guideline provides safety pelfolmanee criteria for exhaust ventilation of semiconductor
manufacturing equipment (SME) and test methods for assessing conformance to those criteria.
1.2 The optimization of exhaust ventilation is becoming man: important as energy efficiency and the physical
constraints of exhaust ventilation utilities in user facilities become more pronounced. Efficiently designed exhaust
ventilation should be provided to protect personnel, property, and the environment from health and safety risks. The
purpose of this safety guideline is to provide performance and tocsin principles and test methods and criteria for
exhaust ventilation.
2 Scope
2. I This guideline applies to semieonductol' manufacturing equipment that incoiporates exhaust ventilation intended
to he cultncctcd to user facilities' exhaust ventilation systemtsl.
2.2 The criteria of this document should be applied to exhaust ventilation systems provided for lhc purposes tin
whole of' in part) of personnel protection, equipment protection, and tire risk reduction,
2.3 The pertbrmanee and assessment criteria in this document apply to all of the equipment provided by a supplier
to a user or to another supplier to he provided as part ofequipmeut the latter supplier provides to a user.
2.4 This document is intended to help the semiconductol' equipment supplier design equipment exhaust ventilation
systems to a common set of performance criteria as well as to provide assistance to both users and suppliers in the
understanding of exhaust ventilation requirements for equipment systems. It is not intended to establish design
specifications.
NOTE I: Design suggestions for several applications of exhaust ventilation are provided as Related Information.
2.5 Test methods are provided in § 8 and several appendices.
2.6 This document is not intended to limit hazard evaluation methods or control strategies 1e.g,, design principles)
employed by suppliers or users. Many different methods may be employed if they provide a sufficient level of
protection.
2.7 Crrnfrnts
l.
Purpose
2.
3.
Scope
Limitations
4.
5.
Referenced Standards and Documents
Terminology
6.
Design Criteria
Performance Criteria
3, Validation Methods and Reporting
9. Minimum InfOrmation Provided to End User
IO. Related Documents
7.
1
SEMI S6-D707 © SEMI 1993, 2007
semi
Appendix l
-
Detelinination of Gas and Vapor Generation and Release Rates
Appendix 2 - Test Method for Detemiining Fugitive Emissions by Using Tracer Gas
Appendix 3 - Test Method for Aerosol Visualization
Appendix 4 - Test Method for Air Patten Assessment For Flammable Gas And Vapor Sources
Appendix 5 - Test Method for Face Velocity Measurement
Appendix 6 - Test Methods for Flow and Pressure
NOTE 2: At the time of publication, SEMI Stu-GTO? contained the following Related Information sections:
.
.
.
.
I'
.»
•
Related lnihrmation l - Example Exhaust Ventilation Parameters
Related Information 2 - Relationship to FarsiIity Exhaust Ventilation Systems
Related information 3
General Design Recommendations
Related Information 4 - Controlling Objectionable Odors from Process Equipment
Related Information 5 - Recommended Fonn for Reporting Exhaust Ventilation
Related Infomiation 6
General Equation Relating Process Gas Flow Rate to Tracer Gas Injection Rate
Related Information T - Exhaust Ventilation as Smoke Control
3 Limitations
3.1 This document does not provide criteria
tel' detelmining whether exhaust ventilation is to be used to mitigate the
risks of the use of a substance within SME. It provides criteria for exhaust ventilation features of SME when exhaust
ventilation has been selected as 8 means of mitigating such risks.
3.2 Effluent sampling for environmental criteria is not covered in this document, Mass balance
environmental characterization is not covered in this document.
sampling tor
NOTE 3: Guidelines for Environmental Chal'acteri:\'ation of Semiconductor Equipment, TT# 01 l(}4197A-XRF |
contains
information on environmental characterizations.
3.3 Ventilation for particle control tbl' product
guideline.
3.4 Ventilation for control of smoke is outside
(Le
'III-t]1l':r than ful safety) is outside the scope of this safety
l
NOTE 4: Ventilation for control of smoke is discussed in Related Information 8 of this document and in a Related information
ollSEMI $14.
3 .5 Ventilation for removal of heat is outside the scope of this safety guideline.
NOTE 5: Because of the cost of conditioning air, particularly
substantially to the capital and operating eosL~L
am' eleanrooms,
using exhaust ventilation to remove heat may add
3.5 This document is written with the assumption that the users' exhaust ventilation distribution systems will be
designed with central fans. ducting, and, where applicable. abatement equipment. Suppliers should be aware that
other types of exhaust ventilation systems may be encountered. End users should communicate relevant details of
their exhaust ventilation systems to their suppliers, particularly if the systems deviate from the assumed model.
3 .7 Existing models and subsystems should continue to meet the provisions of SEMI $6-93. Models with redesigns
that signitieantly affect the EHS aspects of the equipment ventilation should conform to the latest version of
SEMI So. This safety guideline is not intended to be applied retroactively.
NOTE 6: El IS aspects of equipment ventilation may be affected by changes to ventilation and by changes to the hazards the
risks of which are mitigated by ventilation.
NOTICE: International System of Units (Sl) units of measure, symbols and abbreviations (as expressed in
standards such as IEEEIASTM SI-10
of'
National Institute of Standards and Technology (NIST) Special Publication
330 (SP 330), "The International System of Units {SI}"} appear in this document as the official units of SEMI
I SEMATECI-I. 2706 Montopolis Drivc. Austin. TX 7374 l. USA. Telephone: 512.356-.35l]U; hltn;.F»'\=l'\lp.l,f,&t;l11:q\l;qh,»;l[i' URL for this document:
hw:»"!
.semalech.o1'g-"p1lbli4:-'do1:ul:rasef'8bsh'acts-"4 l*}7axfr.hlm
SEMI $6-0707 @ SEMI 1993, 2007
2
semi
Standards publications- They may be followed (in parentheses) by US Customary units of measure for convenience,
bLlt the Sl units define the criteria.
NOTICE: This safely guideline does not puipurl to address all of the safety issues associated with its use. lt is the
responsibility of the users of this safety guideline to establish appropriate safety and health practices and determine
the applicability of regulatory or other limitations prior to use.
4 Referenced Standards and Documents
4.1 SEM! Srurzdrxrds' and Sufctv Guidelines
SEMI FS - Guide for Gaseous Effluent Handling
SEMI $2
-
SEMI $14
Equipment
Environmental, Health and Safety Guidclinc for Semiconductor Manufacturing Equipment
-
Safety Guidelines for Fire Risk Assessment and Mitigation of Semiconductor Manufacturing
SEMI $22 - Safety Guideline for the Electrical Design of Semiconductor Manufacturing Equipment
4.2 ACG1H=iC'-'
Threshold Limit Values tor Chemical Substances and Physical Agents and Biological Exposure Indices
4.3 AS'HRAE"
Standard 1 10-1995 -
Method of Testing Perfollnance of Laboratory Fume Hoods
4.4 ASTM SmrrdurdJr
ASTM E 697
Practice for Use of Electron Capture Detectors in Gas C hromatograplly
IEEEIASTM Sl 10 _ American National Standard for Use of the Intcmational Syslcm of Units (Sll: The Modem
Metric System
4.5 CIA standwfaé
CGA P20 -
Standard for the Classification of Toxic Gas Mixtures
CGA P23 - Standard for Categorizirig Gas Mixtures Containing Flammable and Nonflammable Components
4.6 European .S`!undurd.r"'
E N ] 127-1 methodology
4.7
Explosive
atmosphel'es - Explosion prevention
and protection. Part
Basic concepts and
European Directives7
94/9/'C
Directive 94/9/EC Of The European Parliament and The Council of 23 March 1994 on the
approximation of the laws of the Member States concerning equipment and protective systems for use in potentially
explosive atmospheres
4,8 NFPA Srundurds
2 ACGIH {Amcri¢:an Conference cuff Guvi:mm::nt Industrial Hygicnisls), -E500 Glcnway Ave., Building D-7. Cincinnati, UH 4521 1-4438. USA.
Telephone: 513-661-733 I
3 ASHRAE (American Society otl1~{eating, Refrigerating and Air-Conditioning Engineers. Inc.} li'*Jl Tullie Circle. N.E.. Atlanta. GA 30329
USA- Telephone' 14041636-3400; Fair.: [41]-M321-5478; http:.-"."u.fww.ashra::1g
4 American Society of Mechanical Engineers, Three Park Avenue, New "f'urk NY I(1H1r$-5990, USA. Telephone: 800.343.2763 [U.S.»'C'8nud8).
:.' t\vv.'w.lsr\1-:.nr .g
'§*5,3l')0,R43.2Tfi3 {Mexico}, *J73.3E2.1 167 {out:»:ide North Am4:ri4:8}; mL
.
5 CIA [Compressed Gas Assn.-cialion] 4221 Wahiey Rd.. 5"' Flo-or. Chantilly. VA 2015 I , USA. Telephone: 7G3.7RS.27{l~0, Fax: 703.961. I R31
http:-°'."www.cganeI.com
fi European Committee tier Standardization [C'EN}, Central Secretarial, rue de Smssart 35, B-l050 Brussels, Belgium
'J' hl1p:.".»'eumpa.eu.inb':-:marlapi."cgi-"eIg:1_du4:":-4marlal1i'celexplura!l1m-411CELIiKnLLmd1H:&lg=en&numdu4:=3l9'94LGfl»{i9
E National Fire Protection Association. 1 Baltcrymarch Park. Quincy. MA 02269, USA. Tclcphcmc: fr]7.77G8DOU, Fax: 6l7.7'?0.Gl7l'}l],
http:-"."www.nl'pa.org
3
SEMI $6-0707 © SEMI 1993, 2007
semi
NFPA I -
Uniform Fire Code
NFPA 497 - Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of
Hazardous {Classified} Locations for Electrical Installations in Chemical Process Areas
NFPA 704
_ Standard System for the Identification
of the Hazards of Materials for Emergency Response
4.9 National Institute of Standards and Teclinnfogy
Special Publication 330 tSP 330), "The lnlemational System oflUnits tSl}"
5 Terminology
5.1 Abbreviations and Acronyms
5.1-1 AEV
additional exhaust ventilation
5.1.2 ATL
-
accredited testing laboratory
5.1-3 C -
ceiling limit
5. 1 .4 ERC -
equivalent release concentration
5.1.5 .FEV -
facility exhaust ventilation
5.1.6 HEl -
hazardous energy isolation
Immediately Dangerous to Life and Healfll
5.1 .7 IDLH
5.1.S LFL
5.1.9
-
(JEL -
5.1.10 FEW
lower fl allnnnullh
eecupati.
ptll'[13]'y1
5.1.11 SEE - secondary exhaust ventilation
5.1.12 SME -
semiconductor manufheluring equipment
5. 1.13 SOC - substance of colicern
5.1.14 STEL- >iliortTertn Exposure Limit
5. 1.15 TWA
|'
IIIIC
Weighted Average exposure limit
5. 1.I6 UPL - upper flammable limit
5.2 Deffirzirions
5.2.1 access - the means of inserting a tool or any part of the hwy into an enclosure.
5.2.2 accessway - a feature of the equipment that allows access. The term includes beth openings that are provided
with a means of closure le.g., a door or removable cover) and those that are not.
5.2.3 additional e.rfu1u.~:r venrifufion {'AEV) - airflow that is riot present during normal operation but is provided to
extract substances of concern during maintenance or in the case of an abnormal release from primary containment.
NOTE 7: Additional exhaust ventilation may he turned on either automatically te.g., in response to leak detection) or manually,-',
and it may he provided through the ducting used for primary or secondary exhaust ventilation (by increasing the volumetric flow
later 01' through separate ducting {e.g-, a flexible duct t"elephant trunk"l used br process chamber cleaning).
5.2.4 balancing
-
adjustments made to airflow rate (e.g., by setting positions of dampers
after the ventilated
equipment and the exhaust ventilation system are installed to assure that airflow to each piece of ventilated
equipment is within design specifications.
5.2-5 capture - entrainment of umiesirahle elements (gases. fumes, vapor, and particles) in the exhaust ventilation
stream fOr removal.
'J National Instilutc of Standards and Technology, 100 Bur-can [}riw:, Stop 3460. Gailhcrsburg. MD 203'-SN?-3460. USA. Telephone:
301.'975.6478, http:»".-'www.nisl.gov. URL fm' this publication: http:»".-'ph',fsi¢:s.nist.gr.w."Pubs-"SP33U."sp33\'J.pdf
SEMI $6-0707 @ SEMI 1993, 2007
4
semi
5.2.6 ceiling finis (C) - an occupational exposure limit (GEL) tor the maximum concentration to which a worker
may be exposed at any time.
-
5.2.7 dosed proc.'essing equipment
equipment in which the process and chemical handling lake place inside of
components the interiors of which are not in communication with ambient air, Components inside the ventilated
enclosures may include sealed mixing of' measurement vessels and holding tanks, enclosed plumbing, and process
chambers. In this type of equipment it is not normal operation for the inside of the ventilated enclosure or the
secondary containment to be exposed to chemicals.
5.2.8 continuous air sampling - performing instantaneous air sampling at a frequency of at least once each fifteen
minutes.
5.2.9 dilute
-
5.2.1l.i ejluenr
suspended in it.
to reduce the concentration of a substance by addition of materials that are not substances of concern.
-
the air removed from SME by exhaust ventilation, including any material mixed with
of'
5.2.1 l enclosure
a physical structure that separates a space iii which exhaust ventilation is provided from another
such space or from a space in which ventilation is not provided.
5.2. l 2 equivalent' release c.'onr'en!ration (ERC) - the theoretical concentration of a substance of concern that would
he measured in air inside or outside an enclosure in the event of a primary containment failure. The ERC is
calculated from the measured concentration of the gas that is released to perform the test. The ERC can be expressed
as a percentage of the DEL
of'
5 .2. I3 exhaust wvmiiurian
as defined herein.
LFL of the substance of eoncem.
any of primary, secondary, or additional exhaust ventilation ii .C.., FEW, SEV. or AEV}.
-
5.2.14 f¢.r¢-fifty exlzuust ventiiatifrn (FEV)
removal of air and the contaminants, if any, contained therein, from
SME or its immediate proximity. FEV is a service provided by a facility, usually through a duct.
5.2.15 jlarnmahle gas - any gas that forms an ignitable mixture in air at 20oC (6l'l'"F1 and 1{)l.3 kPa t14.'? psi).
This includes. by definition. any pyrophoric gas. (As used in this definition, "an ignitable mixture with air" is
4
mixture that can be ignited.)
NOTE 8: Within some regulations. pyrophoric materials are considered di fferently than are other flammable materials.
5.2.16 ,flmnmoble liquid - a liquid having a flash point below 37.3DC 1l(l0oF}.
5.2.17 flarmnable range - the tango of concentrations of the dispersed chemical species in air through which a
flame will propagate if a source of ignition is supplied. This range is bounded by the lower flammable limit {LFL}
and the upper flammable limit (UFL).
NOTE 9: The following pairs of terms are commonly used interchangeably:
"lower explosive limit {LEL}" and "lower tlamm~ file limit (LFLl";
"upper explosive limit qUELl" and "upper flammable limit tUFLl". and
"explosive range" and "flammable range".
Some literature uses "LEL",, "UEL". or "explosive range" to designate concentrations to which a more specific criterion {e.g., a
certain pressure rise or flame front spcedl than the ability to propagate flame pertains. This document uses the "flammable range"
terminology to avoid the ambiguity that accompanies the "explosive range" terminology.
5.2.18 flash point
the minimum temperature at which a liquid gives off sutlicient vapor to form an ignitable
mixture with air near the surface of the liquid ot' within the test vessel used. As used in this definition, "an ignitable
mixture with air" is a mixture that can be ignited.)
5.2.19 ,flow .sensor - a device which measures the movement of a fluid. Flow sensors may measure by comparison
of pressures or by other means.
5.2.20 ,flow r'eloc'ir'y. V
the average speed at which an effluent stream travels through an exhaust ventilation duct.
lt is commonly expressed in meters per second rrnfsl. The US Customary unit is feet per minute lfpml.
5
SEMI S6-D707 © SEMI 1993, 2007
semi
5.2.21 jiow volume.
Q-
the volumetric flow rate of an effluent stream passing a given location in the ventilation
system per unit of time. lt is commonly expressed in cubic meters per hour tm3fhr). The US Customary unit is cubic
feet per minute tcfm}.
5.2.22 fugitive, adj. - escaping. from the ventilated enclosure that was intended for its control. into the work area.
5.2.23 gas
the fluid form of a substance in which in can expand indefinitely and completely fill its container,
form that is neither liquid nor solid. [SEMI $4. SEMI F7R, SEMI FSI]
5.2.24 hood - a shaped inlet designed to capture air and conduct it into a facility exhaust ventilation duet system.
5.2.25 Irnrnedirrrdv Dangerous m Life or Health UDLHJ - an atmosphere that poses an immediate threat to life,
would cause irreversible adverse health effects. or would impair an individual's ability to escape from a dangerous
atmosphere. [29CFRl9 l U.l 34b]
5.2.26 inch of wafer gauge ( "w.g.. in. w.g., or i.w.gJ
the pressure that supports a column of water one inch tall. It
is a common US. not SI, unit tor pressure. (See also the definition tor static pressure.)
5.2.27 integrated air .rumpling - moving potentially contaminated air at a known rate for a known sampling period
through a medium suitable for collecting and retaining the contaminants of interest for' subsequent chemical analyst S.
Integrated sampling provides a means of measuring the time average airborne concentrations of the contaminants
during the sampling period.
5.2.23 in.rruntunen»u.r :fir .sampling - collecting potentially contaminated air' for chemical analysis as rapidly as the
collection method pe mils. Typlcilly, the cnlluut-Inn Uma it lass Ann Una *flute per' sample. Instantaneous sampling
provides a means of nrnnuming gliilbulrnn nnmnnninatinuln of'
durine a brief period
5.2.29 r'ower.flornrnalll'l
Ella
:substance in air through which a flame
will propagate. See all
It
5.2.30 hung radius eu
diameter.
one radius 1.5 or more times the duct
_
5.2-31 mninnrnunce
- planned or unplanned activities intended to keep equipment in good working ordel'. (See
also the definition for sent-re.) [SEMI $2]
NOTE IO: "Unplanned" means that the activity had not been scheduled. i.e.. that the activity is performed in response to an
observed condition. "Unplanned" does not mean that the activity had not been foreseen or that the equipment supplier had not
provided instructions for peribrrning the activity.
5.2.32 miilirnerer of water gauge, mm. w.g. - the pressure that supports a column of water one millimeter tall. It is
a common, not Sl. unit for pressure. (lt is also called mm Aq.l See definition for static pressure.
5.2.33 nun-crnnbusribh' material - a material that, in the from in which it is used and under the conditions
anticipated, docs not ignite, burn, or release flammable vapors when subjected to Ere or heat.
5.2.34 mrrrupufirmui e.rpr1surr* limit (GEL) - the maximum airborne concentration of a substance to which a worker
may be exposed for the specified time. OELs include TWAs, STELs, and Ceiling limits, which differ in the time
period for which they specify concentrations. Various terms are used to refer to OELs, such as permissible exposure
levels. Threshold Limit Values®. maximum acceptable concentrations, maximum exposure limits. and occupational
exposure standards. The criteria used in determining OELs can differ among the countries that have established
values. (Threshold Limit Value is a registered trademark of the American Conference of Governmental Industrial
Hygienists.l
5.2.35 open processing equipment - equipment in which at least some of the process and chemical handling take
place inside of components the interiors of which are in communication with ambient air. In equipment of this type.
such areas of the primary containment are ventilated.
5.2.36 pocketing - aeeumulatiolr in a portion of a ventilated enclosure of a released SOC at a concentration greater
than the ratio of the rate of release to the volumetric airflow through the enclosure. Pocketting may result i f the
linear velocity and mixing of airflow within the enclosure is not unitbIm.
5.2.37 primwjv <~nntainmf»nr - the first level of containment ti.e., the container. piping. or other component) that is
intended to come into immediate contact on its inner surtax-ace with the material being contained during normal
SEMI $6-0707 @ SEMI 1993, 2007
6
semi
operation, maintenance and service. Primary containment does not include exhaust handling components tag..
ducting and exhausted enclosures).
5.2.38 primary €.1:flaus1' twnifufion (FEW) the equipment.
airflow that, in normal operation, extracts substances of cuneem from
NOTE I I : For example, the exhaust ventilation provided to collect and extract the vapor that leaves the liquid surface in an open
processing vessel is considered primary exhaust ventilation because evaporation of substances of concern from the liquid surface
is expected during normal operation.
5.2.39 prfnw-'~33 vessel
vibration.
primary containment in which substrates are exposed to chemicals. heat, radiation.
5.2.40 pi-mpNnric nrnterin! -
8
Of'
chemical that may ignite spontaneously in air at or below a temperature of54-44a{i`
{l30'"F).
5.2.41 safe condition -
a condition in which the equipment does not present an unacceptable risk to personnel,
itself of' the facility. A safe condition is determined by the designer of lhc equipment and is based on the risks in the
design.
5.2.42 .wtwndory winrufnnufnr - the second level of containment, the purpose of which is to contain substances of
concern should they be released train theil' primary containment due to failure or to maintenance or service
operations. This peltains to both liquids and gases.
5.2.43 seeonduq' exhau.rf
t-'en tilurirm
(SEE) -
airflow that. in normal operation of the equipment. does not extract
substances of concern, but operates continuously to extract substances of concern should they be released from their
primary containment due to failure or to maintenance or service operations.
NOTE 12: For example. the exhaust ventilation through gas panels is considered SEE. because in nonna operation. the
liasfardous gases are within their piping and only under failure, maintenance, of' service are hasrard-ous gases removed by the
exhaust ventilation .
5.2.44 .semiconductor manufacturing equipment (SME) - equipment used to manufacture. measure, assemble, or
test semiconductor products. lt includes the equipment that processes substrates {e.g.. silicon wafers, reticles. its
component parts. and its auxiliary. support or peripheral equipment {e.g.. chemical controllers. chemical delivery
systems, vacuum pumps). SME also includes other items {.e.g.. structures, piping, ductwork, etlluent treatment
systems, valve manitbld boxes, filtration, and heaters) specific to and provided with the aforementioned equipment.
but does not include such an item if the item is part of a facility and can support more than one piece of SME.
[SEMI $3]
5.2.45 .bonfire - unplanned activities intended to return equipment that has failed to good working order. (See also
the definition for inointefmnce.) [SEMI 52]
5.2-46 short term exposure limit (STEL) - an occupational exposure limit {(}EL} for an exposure period much less
than a work shift. typically fifteen minutes. The time period is specified as part of the STEL.
5.2.47 static pressure, SP
the measure of differential pressure across a duct or enclosure wall. That is. the
difference between the ambient (pressure of the room in which the duet is located) and the pressure inside the duet.
This is usually expressed in Pascals Pa)
of'
inches of water.
NOTE 131 One inch of water gauge {"w.g,} equals 249 Pa. One pascal equals one newton Pei' square meter iwm1i.
5.2.43 smric pressure .rvn.rnr - a device which measures static pressure.
5.2-49 substance of concern (SOC). n. - a substance for which the equipment relies on exhaust ventilation to
protect personnel from exposure above the limits established in SEMI $2 or to prevent formation of a mixture with
air at above 25% of the LFL of the substance during normal operation, during maintenance, or in the ease of failure.
This includes substances meeting the criteria in the definition that are to he used in processes, those that are products
or byproducts of intended or foreseeable reactions, those that are not intended to be directly ilwolved in the
processes {e.g., coolants} and those that are used only in maintenance Ur service te.g., solutions used to clean process
chambers-I.
NOTE I4: Whether a solution or mixture is a substance of coneem depends on the properties of the solution or mixture. as it is
supplied to the SME. not on the properties of the constituents. unless it is reasonably foreseeable that the solution or mixture will
7
SEMI $6-0707 © SEMI 1993, 2007
semi
/' HE in N; is not a flammable gas. although HE itself and a 5% H: in He
separate into its constituents. For example. a mixture of 5%
mixture are flammable gases. CIA F23 and P20. respectively. provide guidance on determining the properties of gas mixtures
containing tlammahle and toxic cumpnrtents.
5.2-50 suh.f;tance-ot'-corrcem, adj. or adv.
pertaining to a substance of concern.
5.2.5 1 supply venfiiurion - the delivery of air to SME or a workplace.
5.2-52 time u'efgha»ed average (TWA) - an occupational exposure limit (GEL) for an exposure period on one work
shift. typically eight hours. The time period is specified as part of the TWA.
5.2.53 .traverse rneusurernenrs
multiple airflow measurements taken al paints of equal separation. by area, in a
matrix pattern. along the cross-section of a ventilation duct or face plane car an opening in a ventilated enclosure.
5.2.54 upperjfammubh' ffmif - the maximum concentration of a flammable substance in air through which a flame
will propagate. (See also the definition for flammable range-)
5.2.55 \~'a,fJor -
the gas phase of a substance that is usually considered to be a liquid-
5.2.56 item: contracts! - a location downstream of an orifice (e-8., the opening of a duct) where the static pressure
t`alls lo a minimum and the velocity pressure reaches a maximum.
5.3 .S`wnhols
5.3.1 'II
a character used lo identify a particular paragraph of the document. The identified portion includes the
numbered paragraph identified by the number following ihu ljrmbul ad 'Igor Exceptions and lists (bulleted or
numbered) embedded therein. lt does not, howe, war. inc
to headers and paragraphs. When
duplicated, as 11
| |. it refunnu
lhanunnpnnlmlph.F
refsis to the text immediately following
that number. the bulletsd
»' that paragraph, but not to 1 3.5. l .l.
s.5.1.;z, or 3.5.1.2.1.
I
1
5.3.2 § - a character 1
includes the numbered pulglnnh urhnndnr
e document. The identified portion
i
_
fig the symbol and all subordinate
headers and paragraph s as well as the Exceptions and Ii
dnrnu mbcredl embedded therein. When
duplicated, as §§, lt' refers to more than one section of' subsection. For example, § 3.5 refers to 1111 8.5, 3.5. l , 8.5. l . l ,
s.5.l.2, s.5.1.2.l, 8.5.2, and 3.5.3 (including the bulleted items and the Exception).
6 Design Criteria
6.1 The: material in § 6 of this document should he used to dotormiru: confonnancc to this document.
6.2 Components should be rated and suitable for their intended use including consideration of at least: pressure,
temperature, and chemical compatibility),
NOTE I5: SEMI $2 includes additional criteria on suitability and application of components.
NOTE 16: Related Information 3 contains recommendations on equipment ventilation design.
6.3 Materials and Crsrnprrnvnts Crnrrpatihifity
6.?».1 All primary and secondary containment components and exhaust ventilation system components, including
enclosures and connecting duct material, should he compatible with the process chemicals specified by the SME
supplier and all rcasonalnly foreseeable process byproducts they may contact. For equipment in which diflfel'cnt
exhaust ventilation systems may convey different chemicals. the appropriate materials should be used in each
location within the equipment.
6.3.2 The materials of eonstmction for ducts and other components that come in contact with efiiuent should he
resistant to the effects leg., corrosion, softening, or emblittlementi of that effluent.
NOTE la: The combustibility criteria of SEMI $2 may limit the choice of duet material- Refer to
information-
1
7.5.4 for additional
6.4 Setup and Ba fancirtg
6.4.1 The provisions of § 6.4 do not apply to automated dampers.
SEMI S6-0T07' @ SEMI 1993, 200?
8
semi
6.4.2 The supplier may provide a damper, at or near the equipment connection point, to be used only as a trimming
device to meet the equipment flow and pressure specifications.
NOTE lil: Dampers that arc balanced in the nearly closed position are more prom: to plugging when the eiTlLlent contains
materials that are likely to deposit on surfaces in the exhaust ventilation system.
6.4.3 Gates and dampers should be seeulable with a tool or lock to prevent inadvertent or unauthorized adjustment.
6.5 Exhaust ventilation for maintenance procedures should either be incorporated in the system design or AEV
criteria should he specified separately from the system PER and SEV. Where exhaust ventilation for maintenance
procedures is incorporated into the equipment, the How and static pressure required to be provided by the facility are
pale of the requirements specified for the SME. When AEV is needed. the equipment supplier should specify the:
.
I
inlet size and shape,
minimum and maximum How, and
.. minimum and maximum static pressure.
NOTE l'-Q: Both static pressure and flow must be specified to ensure that the pressure drop in the AEV equipment dues nut
ieduee the flow below that which is needed to capture the SDC.
NOTE 20: lt is recommended that capture occur as close to the source 113 practical to manage exposure of personnel or pro-duct:-L
to the SOC.
NOTE 2I: This criterion is intended to deserihe how exhaust ventilation for maintenance is to he provided. lt is not intended to
state that such ventilation is appropriate for all SME nr all tasks.
(1.6 The SME should not require that the facility provide a static pressure more negative than -375 Pa {-33mm H20
or - I .5 i.w.gl at the point of connection to the facility to meet the other performance criteria in this document.
EXCEPTION: If the equipment {e.g., eoalerl design requires pressure more negative than -375 Pa, an technical
rationale for the additional static pressure demand should be provided to the end user. Additionally. methods should
be described for achieving the necessary static pressure and means (e.g., interlocks) should lie described that will
prevent any portion of the exhaust line from reaching a positive pressure. This information should be supplied in the
documentation provided to the end user.
6.7 Points of eonneetion to facility exhaust ventilation system should be of a size, shape and material that are
eompatilile with commonly available duct materials.
7 Performance Criteria
7.1 The matelial in § 7 of this document should bf: used to determine conformance to this document. These criteria
pertain only when the acceptability of the risk depends on the performance of the ventilation.
NOTE 22: As there were no criteria for exposure during service specified in SEMI $2 at the time this version of SEMI $6 was
developed, no criteria for exhaust ventilation performance for service are included in this document. However. the same methods
used to determine the adequacy of exhaust ventilation for maintenance could be used for service. if exposure criteria were
established. In the absence of criteria. concentrations and potential exposures at the time of service need to be assessed and
appropriate protection needs to he provided for personnel who are to perform service.
7,2 Rr*t'eu.~rr* and' Generation Rates
7.2.1 To test the adequacy of the exhaust ventilation by simulating a release, one must establish the mass or
volumetric flow rate and velocity at which gases (including vapors) and aerosols of the substances of concern are
reasonably foreseen to be released or generated in normal operation. during maintenance. and during failures (e.g..
overtemperature of a bath or leak of primary containment1. The determining factors include the physical state of the
substance of concern {i.e., solid, liquid., or gas) and the conditions {e.8., temperature and pressure) under which it is
handled and used in the SME.
7.2.2 Liquid sources that require equipment exhaust ventilation can be grouped several ways. They can be grouped
by whether the liquid is exposed to the atmosphere under normal operating conditions {e.g., in an open-tank wet
station), or only under maintenance conditions (e.g., wet cleaning a CVD process chamber), or only under abnormal
conditions leg., a leak in a liquid supply line to a CVD process chamber). Liquids can also be grouped by the
hazards they present: toxicity, Ilarnmability, or both.
g
SEMI $6-0707 © SEMI 1993, 2007
semi
7.2.2.1 As the management of the liquids themselves is outside the scope of this document and the only differences
between liquid and gas releases are the rate and location of the release and, in the case of liquids. of the conversion
to vapor, the methods described for gas releases may be used.
7.2.3 C'!o.red Prrtr.'e.s.ting Equipment
12,.,1 In normal operation, no substances of concern are released to, or generated in, ventilated enclosures of the
equipment or work environment.
7.2.3.2 The release or generation Tate during maintenance depends on the equipment, its use, and the maintenance
activity. For maintenance activities that involve opening the primary containment of the substances of eoneem, see
the discussion below 1§ 7.2.4) regarding open processing equipment. In maintenance activities in which primary
containment is not opened. there is
Ito
substance of concern released to, or generated in, the ventilated enclosure.
7.2.3.3 All reasonably foreseeable, single fault conditions (e.g., overheating, overpressurization) should be
considered. Additionally. for liquid and gas piping systems. the disconnection of each non-welded eonneelion
should be considered, whether or not it is "reasonably foreseeable". Releases from failure should be estimated as
follows:
NOTE 23: lt is recommended that SME manufacturers speciljf the maximum inlet pressure under facility fault conditions for
which the SME is suitahlc.
'7.2.3.3.l For foreseen failure points in gas and liquid piping systems (including each non-welded connection), the
release rate specified herein is the rate at which the substance of concern would How if the primary containment
were disconnected at the point of failure. This depends on the substance of coneem, its pressure, and the flow
limitation (deliberate, e.g., by flow limiting devices or incidental, e.g., by filters) imposed by the engineering
controls in the fluid source and the primary containment system. Appendix l provides conservative models for
estimating the release of a gas from a disconnected line and for estimating t'l-nn'-l.l-1-l~ n u n - . - n n In to from release of
liquids. These models should be used if the release or vapor generation rate I
beam
'7.2.3.3.2 The engineering controls may be incorporated I.n the SME or l
may specify, in
documentation provided lo the user, that the flow of a substance of concern Ii-om a facility to the SME he limited, by
an engineering control, to a particular value. The release rate used in determining eonlbrmance to this safety
guideline should not depend on administrative controls, such as assembly and leak checking procedures.
i
.-
"
"
"
_
he
NOTE 24: The task force that developed this document could not reach consensus on a
t less conservative,
release rate other than the total available flow of substance of concern. Exhaust ventilation
r depend on supplier
or user choices as to how much flow to make available. Engineering controls, such as excess flow valves, flow switches and flow
testrietors can be used to limit the available flow and, thereby, reduce the exhaust ventilation required.
7.2.3.3.3 For foreseen failure points in vessels. the release rate depends on the failure mode.
NOTE 25: Vessel failures range iron the development of pinholes, which might release fluids at rates of less than one liter per
hour, to rupture, which might release the entire liquid volume in le:-Ls than one second.
7.2.3.3.4 The quantity or duration of a release is limited by the available substance of concern. This is limited by the
amount of the substance of eoneem in the equipment, if there is no external supply of the substance of concern.
7.2.3.f'+.5 The quantity or duration of release may also be limited by automated interruption of the substanee-ofconcern supply to the failure point, if both of the following conditions are met:
•
The means of detection of release has been found by an ATL to conform to 8 relevant performance standard
{e.g., FM632(), ANSI-[SA l2.l3.()l or CSA 22.9 No. 152 for combustible gas sensors). For the purpose of this
criterion, a "performance standard" is one that specifies the ability of the detector to dctccl lhc SOC.
The means by which the signal iron the detector results in stopping flow meets the SEMI $2 cliteria for safety
interlocks.
72.3.3.6 For substances of eoneem that are released as liquids or aerosols, see Appendix 1 for the means of
determining the vapor generation late.
SEMI $6-0707 © SEMI 1993, 2007
10
semi
7.2-4 Open Processittg Equipment
'7.2.4.l In Norma! Operation
7.2.4. I .I The late at which open portions of the system {.i.e., those portions in which the substances of concern are
exposed lo the ventilated space) release or generate substances of eoneem into the ventilated space depends on the
substances of concern and physical conditions of the exposure. If the adequacy of the exhaust ventilation is to be
tested by simulating a release, the methods in Appendix I should be used to determine the vapor generation late.
7.2.4. I -2 No substances of concern are released from closed portions of the primary containment to the ventilated
enclosure of' work environment.
7.2.4.2 During Maintenance
7.2.4.2.1 The release or generation rate during maintenance depends on the equipment, its use, and the maintenance
activity.
72.4.2.2 For' maintenance activities that involve open portions of the system, release or generation of substances of
concern into the ventilated space depends on the substances of concern and physical conditions of the exposure. If
the adequacy of the exhaust ventilation is to be tested by simulating a release, the methods in Appendix I should be
used to determine the vapor generation rate.
NOTE 26: Opening accessways m~ y cause co noes in the exhaust ventil~ son conditions. including the velocity and flow volume
of air past the exposed subst~ rices of concern.
NOTE 27: In many equipment configurations, personnel performing maintenance may occupy locations that are not occupied by
personnel during normal operation.
72.4.2.3 For maintenance activities that involve opening the primary containment of the substances of concern in
closed portions of the system, the release or generation rate should be determined as if the involved portion of the
system were open.
'7.2.4.2.4 in maintenance activities that involve closed portions of the system but in which primary containment is
not opened. there is no substance of concern released to. or generated in. the ventilated enclosure.
7.2.4.3 During Fault Conditions
7.2.4.3.1 All reasonably foreseeable, single fault conditions should be considered. Releases from failure should he
estimated as tallows'
72.4.3.2 The release resulting from failure of primary containment should he determined as is described above for
closed processing systems.
7.2.4.3.3 The release rate during other failures 1e.g., abnormally high temperature of an open container of liquid) is
determined by using the methods for normal operation, substituting the failure conditions for the normal opctaling
conditions.
7.3 Genera! Criteria
7.3.1 SME design should include means of mitigating the risks associated with the total loss of facility exhaust
ventilation or with loss of facility exhaust ventilation to below the levels that enable the equipment exhaust
ventilation to perform the functions described in this safely guideline. Selection of such means should be based on
the result of hazard analysis and risk assessment and provide automatic actions 1e.g., drain chemicals, shut off'
source, cover open vessels) to place the equipment in a safe condition. Different means of risk mitigation may be
required for different equipment configurations {e.g., minienvironmcnt or not) or facility configurations 1e.g.,
laminar flow variations among facilities).
7.3.2 When: the equipment supplier provides written procedures for maintenance litnctions (such as closing manual
valves or adjusting regulators) to be performed without isolating the supply of substance of concern to the enclosure,
an accessway should be designed in a way that will not result in inadequate exhaust ventilation performance. This
criterion pertains only when the acceptability of the risk of performing those maintenance functions depends on the
performance of the ventilation.
NOTE 28: Procedures of this nature may need to be evaluated to ensure that they do not violate regulations regarding hazardous
energy control.
11
SEMI $6-0707 © SEMI 1993, 2007
semi
7.3.2.1 Access to a secondary containment enclosure to perform a maintenance task is considered maintenance only
if there is no release to that enclosure at the time of access, i.e., no release is ongoing at time of access and no
release begins during access. Access to secondary containment enclosures in which releases are oecuning is not
maintenance, it is service, because the release is a failure condition, not a condition ofnonnal operation.
NOTE 29: For example. access to a gas panel enclosure to perform HEI is "maintenance" if the concentration of SEC in the
enclosure is below the limit for exposure for maintenance personnel. (By definition. in normal operation. the concentration is
immeasuralily small.) If. however. there is a leak within the enclosure that would result in exposure above that limit if the
accessway were opened. opening the accessway would be outside the scope of "maintenance". because the leak is a fault
condition-
NOTE 30: It may he appropriate to consider the risk of a maintenance function causing a release (e.g.. a valve being broken as it
is used to perform HEl) in the assessment of conformance to SEMI $2. It may be appropriate to mitigate that risk by ventilation
design. primary containment design, or other means.
7.4 Management
of Exposure
to Personnel
7.4.1 Exhaust ventilation designs for substances of concern should ensure hazardous gases, particles, and vapors are
controlled during normal operations such that cont.:entrations present in the work room air meet the breathing zone
criteria for nonna operations in SEMI $2.
7.4.2 Exhaust ventilation designs tor substances of concern should ensure hazardous gases. particles, and vapors are
controlled during maintenance operations such that concentrations present in the breathing zone of the maintenance
worker meet the breathing zone criteria in SEMI $2. Exposure risks during maintenance should be described and
reeommendatiunlmad:llJ:ull:lt'tl:n:u:]1nll1ltwl:rtiln:Encnvnlnnrmulrin fInwlr"*potential methods for providing exhaust
ventilation dui' iugnuIlindaammlnnu
7.4.3 Exhaust 1
controlled dur
re
h12ardors
gases, particles, and vapors are
lair meet the breathing zone critelia for
failures in SEMI SI
7.4.4 If the realncl:llibI;lrfnm:iTuuT:1eb.itl:ingmlEEnf
volurnc within
:l1ennlnnmu,1ilu\m1tilad:Innmhnuldpnuluda
action. maintenance or service includes a
ii-Hun those portions of the enclosure
NOTE 31: If the protection of personnel performing service (i.e.. working on equipment after a failure) depends on exhaust
ventilation. it is recommended that the exhaust ventilation design ensure that no reasonably foreseeable breathing zone within an
enclosure has a concentration in excess of one half of the IDLH. This can be achieved by any of several means. including having
SL11'Ticient airflow to dilute to that level or precluding access to an enclosure until after the release has been stopped and sufficient
time has passed to allow the exhaust ventilation to reduce the concentration to below the limit.
NOTE 32: Protection of personnel that is provided by controls other than exhaust ventilation {e.g., other engineering controls,
administrative controls. personal pl'ote4:tive equipment IPPED is outside the scope of this document.
7.5 Munogenuf-m' of Fire Risk
7.5.1 There are h o common means of reducing the risk of ignition of atmospheres: reducing the risk of the
presence of such atmospheres and reducing the risk of there being ignition sources in such atmospheres. The
equipment supplier may cheese which of these to use for each location within the equipment. It is nut the intention
of this safety guideline to imply a preference between these methods.
/ of its LFL. oxidizers, and potential ignition
NOTE 33: The risks presented by the coincidence of air containing an SOC at 25%
sources can he addressed by controlling any of those elements. Control of osidizers and potential ignition sources. however. is
outside the scope of this document.
NOTE 34: Ignition sources may not affect the design and operation of pyrophoric substance enclosures. 8S the nature of a
pyrophoric material is that it may ignite on contact with air. However. as the autoignition temperature of a pyrophoric material
may be as high as 54.4=>C U30 oFl. not all releases of pyrophoric material into enclosures will autoignite. For reasons that are not
well understood, some 1'eleases of pyroplioric gases above the autoignition temperature result in accumulation and delayed
ignition. For some materials. the LFL is lower than the minimum concentration for autoignition. so there is a concentration range
in which an ignition source is of concern. Also, stronger ignition sources call increase the pressure rise in explosions.
SEMI S6-DT07 @ SEMI 1993, 2007
12
semi
NOTE 35: Higher than normal (up to l mis (200 fpmll air velocities have been specified to ensure that pyrophoric gases do not
collect arid reach explosive levels. ResearchIn' has shown that air velocity does not atTect probability of ignition at the point of
release for silane. The task force which prepared this version of SEMI Sri is not aware of any experimental proof that air velocity
atTects probability of ignition for airy pyrophoiic gas. Silane pressure at the point of release appeals to he the dominant factor in
determining its ignition behavior.
NOTE 36: User and jurisdictional requirements may he part of the design criteria for pyrophoric exhaust ventilation systems.
7.5.2 During normal operation, maintenance, and all release conditions described in § 7.2, equipment exhaust
ventilation design should prevent accumulation of 25% of the LFL at potential ignition sources within an enclosure
if an oxidizer is present.
7.5.2.1 Exhaust ventilation may be used for capture and removal of flammable gas ar vapor.
7.5.2.2 Exhaust ventilation may also be used to provide dilution with uncontaminated air, which can be used to
/ of its LFL at potential ignition sources.
keep the concentration of flammable gas of' vapor below 25%
7.5.2.2.1 Enclosures for flammable SOCs should be designed to ensure adequate dilution throughout the enclosures
by exhaust ventilation {i.e., prevent "pockcling"l.
NOTE 37: Electrical components located within an enclosure that potentially contains 25% of the LFL may he subject to
regulatory requirements to provide classified electrical components (such as for Class l, Division 2 in the NFPA Electrical Code
of' the Uniform Fire Code). The requirements in these codes for Classified or Hazardous Locations pertain only to electrical
sources of ignition. If there is no electrical equipment in the Location, then these requirements do not pertain. Detailed
information as to whether special electrical designs arc necessary is included in such do-cunrcnts as ENI 127, NFFA 497 and
94."9."EC. NFPA 497 includes, as areas "it is not usually necessary to classify", i.e., that do not usually require special electrical
design:
.
those with adequate exhaust ventilation and combustible materials "contained within suitable, well-maintained closed piping
systems".
those without adequate exhaust ventilation, but piping without accessories that are leak-prone, and
those used for storage of combustible materials in "suitable containers".
7.5.3 The volumetric flow should be sufficient to provide dilution of flammable SOCs to less than 25% of the LFL
{in maintenance
or'
fault conditions (as described in § 'i'-211 at the point of connection of the equipment to the facility,
I otltlre LFL
where dilution is the primary means of limiting flammable S(}Cs to less than 25%
.
7.5.4 Ducting within the equipment should be constructed of non-combustible material leg., ferrous and nickel
alloys when normal operation or maintenance results in either:
1
llammahle gases (including vapors of flammable liquids) above 25% of their LFLs, or
flammable Ur combustible residues deposited in duel work.
EXCEPTION: If the ducting is reasonably foreseen
je
contain >25% of the LFL of paper. but net foreseen to
contain solid or liquid flammable or combustible residues, combustible ducts, ducting components, or materials
found by an ATL to coliform to appropriate standards {e.g., UL 181
Standard for Safety of Factory-Made Air
Duets and Air Connectors, FM 4922
Fume Exhaust Duets or Fume and Smoke Exhaust Duets) may be used.
NOTE 38: Some jurisdictions require tire protection sprinklers in duels with cross section dimensions 8bove certain sizes. Fire
/ of the LFL.
protection sprinklers may be required in either combustible duets or in ducts that may contain 25%
NOTE 39: Some jurisdictions prohibit, or impose additional requirements on, ducts tbreseen to contain flammable materials
above l0% oilLFL.
7.6 E}j'icicnc'.w'Oprimizarion
7.6.1 Demand on the facility's exhaust ventilation systemtsl should be as low as is consistent with meeting safety
and process requirements including minimizing nuisance alanns. Equipment suppliers should design the equipment
to require the least exhaust ventilation feasible to meet health and safety objectives (control of exposure and
reduction of the risk of fire).
10 Tamanini.F.. ('half¢:c J.. "lgnitiml C"hal'actoristics of RcI¢ascs of l00"/u Silanl.:. FMRC J.l.{)ZOR'.',RI'-1. D¢4:¢mbcr 14,I'S .Factory Mutual
Research Colporalion, I 151 Providence Hwy., Norwood. MA 0262
13
SEMI $6-0707 © SEMI 1993, 2007
semi
7.6.1. l This criterion is considered to be met if the airflow does not exceed the greater of:
.
two times the flow necessary to provide dilution of flammable substances of concern to less than 25% of the
of' fault conditions (as described in § 7.2}1 at the point of connection of the equipment to
LFL (in maintenance
the facility, or
l
the flow necessary to provide ten times the volume o f the enclosure's) each minute.
NOTE 40: Five air exchanges per minute is generally considered sutTicient to provide good mixing within an enclosure.
However, this does not relieve one of the obligation to assess performance within enclosures. Furthermore, there are regulatory
requirements for higher air exchange rates in some jurisdictions.
7.6.1 .2 If the How required to meet the health and safety objectives exceeds that described in 1| 7.6, I.l the
equipment supplier should provide users a written explanation of why the criteria cannot be met.
7.6.2 As the exhaust ventilation Flow requirements depend strongly on the potential release, the equipment supplier
should consider limiting the available flow of substances of eoneern, such as with flow restrietors or excess flow
valves, as a means of reducing the required exhaust ventilation flow.
NOTE 4 l : In much of the equipment in use today. the available How within primary containment is much larger than the flow
required for the intended and tinreseeable processes- It is the available tlow{s} of substance's] of eoncem. however, than can be
released during failure opt-imary containment.
7.7 Interlocks and Monimring
7.7.1 Direction ofSu.*>.rronces of Concern
7.7. l . l Equipment that uses substances of concern Ur odorous or ilTitant chemicals should be provided with sensors
to detect releases from primary containment. Allemalively. the equipment supplier may specify the location and
pertbrmanee of detectors, but not provide them, so that the user may better integrate the detection in the equipment
with that in the facility. This alterative should be negotiated explicitly by supplier and user.
NOTE 42: This does not necessitate one detector for each chemical species, just that all species be detected. For example. a float
switch could be use to detect a leak of any of several liquid reagents and a hydride gas detector could he used to detect phosphine.
arsine and tlihorane.
7.7.1 .2 The means of detection should be one 'lliltlllblbanfhlilliId by an ATL to conform to a relevant performance
standard (B.g -1 FM63203 ANSI-ISA 12.13.01 I
52 for combustible gas sensors). For the purpose of
lhility of the detector to detect the SOC.
this critcnott, 8 "pcrtbmlancc standard" is one
7.7.1.3 Gas sensors should be located so that they will detect and respond to a release from primary containment
such that it will not result iii concentrations present in the work l'oom ail' exceeding the breathing zone criteria in
SEMI $2 or concentration of a flammable gas inside or outside enclosures above 25% of LFL at a potential ignition
source.
'7.'1.l .4 The sensitivity of leak detection sensors and systems required should be determined during controls design
and should be based on the hazard ehal'aF:tel'isties of the potentially leaking materials.
7.7.1.5 Gas and vapor sensol's should he located so that they measure the concentration in the airflow from only
those enclosures ill which there can be a release of the specific materials.
EXCEPTION: Sensors may be located so that they measure concentration in airflows manifolded together from
more than one enclosure within a single piece of SME. only if sensitivity of" the sensors used in such a manner is
sufficient to meet the criteria of117.7. I _3_
'7.7.l .6 Liquid sensors may be used instead of gas sensors if they are capable of detecting liquid leaks that could
result in vapors of substances of concern. Liquid sensors should be located so that they will detect and respond to a
leak such that it will not result in exposure above the permissible level (as defined in SEMI $2} or concentration of a
flammable gas above 25% of LFL at a potential ignition source, if an oxidizer is present.
7.7-2 Mnnimring
of Exhaust Vertfiffrrfrmn {Ethau.w Venrilaiion irtrerlnckt)
'i'.'}'.2..l SME incorporating PEV arid AEV systems that are used for' safety should be provided with safety interlocks
to shut down the flow of chemicals to and within the equipment and any other exhaust-ventilation-related hazard
when the exhaust ventilation falls below the levels needed to perform as prescribed within this document.
SEMI $6-0707 @ SEMI 1993, 2007
14
semi
7.T-2.2 SME Incorporating SEE' aha! is Used for Sqfefy Where Detectors for the SOC: are Not Provided in
Aecordcmce with § 7. FJ
Safety interlocks should be provided to shut down the flow of chemicals to and within
the equipment and any ether exhaust-ventilation-related hazard when the exhaust ventilation falls below the levels
needed to pertbrm as prescribed within this document.
7.7.2.3 SME incorporating SEE that is used tor safety where detectors for the SOCs are provided in accordance
with -§ 7.7.1.
7.7.2.3.1 If the exhaust ventilation rate falls below the levels needed to perform as prescribed within this document,
but the detectors for the SeCs do not indicate that SOCs are being released from primary containment and the
detectol's for the SOCs are installed in such a manner that they will detect a leak when no exhaust ventilation is
present, the SME may continue to process the product that it has begun processing. Starting processing of additional
product should be precluded. however, until sulTieicnt exhaust flow and pressure are detected. Software may be used
to preclude starting processing of additional product,
7.7.2.3.2 If the exhaust ventilation falls below the levels prescribed within this document, and the detectors for the
SOCs indicate that SIJCs are being released Item primary containment, the SME should, through the action of safety
interlocks, shut down the [low of chemicals lo and within the equipment and any other exhaust-ventilation-related
hazard.
NOTE 43: The intent is that the equipment include the sensors for the interlocks and that the interlock signal close the first (in
order of process flow) valve in the equipment that can be operated automatically. If the substance of eoneem is supplied to the
equipment through piping. the interlock should also send a signal to the external supply system t.e.g.. hulk refill system) to stop
supplying the substance of concern.
7.7.2.4 Exhaust ventilation monitoring should he capable of detecting the total loss of exhaust ventilation or loss of
exhaust ventilation to below the levels that enable the equipment exhaust ventilation to perform the functions
described in this safely guideline. Upon detection of such a loss of exhaust ventilation, the equipment should
automatically place itself in a safe condition, as described above. (See 'II 7.7.2.2 and § 7.7.2.31.
NOTE 44: Optional responses may be necessary to align with user and regulatory requirements.
7.7.2.5 Exhaust ventilation monitoring and interlock components should he identified as safety critical parts for the
ptlrp4.1ses of SEMI $2 assessments.
NOTE 45: SEMI $2 contains cl'iteria for safety critical pans and describes how they are to be considered during assessments.
7.7.2.6 lt is recommended that flow sensors, rather than static pressure sensors. he used where volumetric airflow is
the characteristic of the exhaust ventilation that controls the risk, such as by dilution of tlammahle gas.
NOTE 46: Flow sensors are less prone to activation by opening the enclosure and they do activate if the intake is blocked.
7,7.2,? Where static pressure sensing is used to monitor both pressure and How, the sensors should detect, and
activate interlocks in response to, both excessive and insufficient static pressure.
NOTE 47: If air inlets arc obstructed li.e., airflow is reduced), the sensors will indicate a more negative (higher absolute value)
static pressure. If onl y insufficient static pressure is monitored, the sensor will not activate an interlock when the air inlets are
obstructed.
7.7.2.8 Static pressure S-€llSO1IS should be used when static pressure is the chal'aeteristie of the exlianst ventilation
that controls the risk. such as by preventing emission of a released toxic gas from a SEE enclosure.
7.7.2.9 A single sensor that measures both flow and pressure may be used if beth flew and pressure need to he
monitored.
7.7.2.10 Static pressure nr flow sensors used for safety interlocks should have sufficient perITr»l'mance to detect
exhaust ventilation flow rate or static pressure conditions outside the ranges for which the exhaust ventilation has
been shown to he effective. The performance characteristics considered should include:
• sensitivity
I
accuracy
C
repeatability
.
hysterisis
15
SEMI $6-0707 © SEMI 1993, 2007
semi
-. deadband
•
response time
7.7.2.1I Static pressure and flow sensors should measure conditions upstream {i.e., on the equipment side) of
dampers.
NOTE 48: Some flow sensing devices require certain duct characteristics {e.g.. a straight portion of dual in order to function.
The exhaust vent Litton sensing device used as alt interlock should he appropriate for the facilitization of the equipment. If a flow
sensing device cannot he found to suit the exhaust ventilation configuration. then a static pressure sensing device which detects
excessive and insufficient static pressure is recommended.
7.7.2. I 2 A time delay in triggering shutdown may be included to enable the equipment to continue to operate during
transient Facility static pressure and flow variations. The devices used to delay the shutdown should coliform to the
SEMI $2 criteria for safety interlocks.
7.'7.2.12.l This is permissible for FEW and AEV only if testing validates that the delay will not result in exposure
above the permissible level or concentration of a flammable gas above 25% of LFL at a potential ignition source.
7.7.2.12.2 This is permissible for SEV only if:
4
.
testing validates that the delay will not result, during a release into secondary containment, in exposure above
/' of LFL at a potential ignition source, or
the permissible level or concentration o f a flammable gas above 25%
risk assessment considering the expected severity of the consequences of and frequencies of releases into
secondary containment and of inadequate exhaust ventilation and whether there are common causes for these
events indicates that the risk presented by the time delay is acceptable.
7.7.3 Alanns and Remote Signaling
7.?.3.l Local tat or within the equipment) visible alarms should be provided for all the SOC' detection and exhaust
ventilation sensors and monitors. This criterion may be satisfied by the use of alerting devices r.e.g., strobes} or by a
.
S
message displayed on the equipment operation console- The alarms hould be located so that the personnel in
locations which may present an unacceptable risk of exposure because of the detected condition, are alerted.
7.7.3.2 Local audible alalms should be proyidW for the detection of the loss or insufficieiiey of FEV or AEV flow
or pressure.
7.7.3.3 Local audible alarms should be provided for the detection of releases from closed processing systems which
occur at the same time as the loss
of'
insufficiency of SEE flow or pressure.
7.7.3.4 The equipment should have the capability to provide signals from the SOC detection and exhaust ventilation
sensors and monitors to the facility ala lm system.
'7.7.3.4.l The signals from SEC detectors should identify the SOC (or type of SOC if the detector detects more than
one SOC) and the location in which it is detected. The signal may report the detected concentration. If the signal
does riot repoit the detected concentration, then the equipment supplier should include, in the documentation
provided to the user, the minimum concentration at which the detector will report. If the minimum concentration to
he reported is intended to be adjusted by the user, then the equipment supplier should include instructions for
making that adjustment and the highest minimum reporting concentration at which the detector can he set to meet
the exposure critel'ia of SEMI $2.
'7.7.3.-4.2 The signals from exhaust ventilation
S€llsolls
and monitors should report the location at which insufficient
exhaust is detected. If static pressure and How are sensed or monitored separately. the signal should report which
condition was detected.
7.7.4 Equipment Respon.t'es - The equipment should shut down the delivery of chemical {.e.g., by closing internal
valves, stopping internal pumps, and relieving pressure in pressure-dliven systems) to the appropriate portion of the
primary containment when a release from a closed processing system or inadequate FEW or AEV is detected.
8 Validation Methods and Reporting
3, I Purposes of tfzis Section
8.1.I The material in § 8 of this document should be used to determine conformance to this document.
SEMI $6-0707 @ SEMI 1993, 2007
_
16
semi
8.1.2 The appropriate validation tests in this section should be used by the equipment supplier or its agent to
demonstrate that the exhaust ventilation meets the perfomiance criteria described in § 7 in normal operating
conditions. during maintenance tasks, and in the event of failure. The validation tests in this Section should also be
used Br the equipment supplier or its agent to establish the values of characteristics (6-8-~ static pressure) that
used to verify that the exhaust ventilation of installed equipment is operating properly.
ar'e
S.l.3 The validation tests in this Section may be used by others, including users, for the same purposes or for such
purposes as validation of the performance of equipment after installation.
3. 1.4 If the installation or facility exhaust ventilation services provided by the user's facility are not as specified by
the equipment supplier, the validation tests in this Section should be used by the user or its agent to demonstrate that
the exhaust ventilation meets the performance criteria described in § 7 in normal operating conditions, during
maintenance tasks. and in the event of failure. The validation tests in this Section should also be used {f`or such
installations) by the user or its agent to establish the values of characteristics (e.g., static pressure) that are used to
verify that the exhaust ventilation of installed equipment is operating properly.
3.2 Test Conditions and Lncatiotrs
8.2.1 As SEMI $2 has different toxic material exposure criteria for' different tasks and states of the equipment, it
may be necessary to test the performance of the exhaust ventilation at different release rates against dilTel'ent criteria.
For' example, it may he necessary to test a wet station with the liquids at the specified operating temperature against
the exposure criteria for' normal operation and at the maximum temperature under' single-fault conditions against the
exposure criteria for' fault conditions.
8.2.2 Measurements should be performed after equipment components are assembled.
8.2.3 Hierarc'h.v.tbr SeTrel'ing Test Sub.s'mm'e.s
S.2.3.1 Where feasible, testing should be performed using the intended suhstanecs of concern and processes in a
representative sample of the equipment.
3.2.3.2 If such testing presents unacceptable risk, testing may he performed as described below, in order of
decreasing preferability:
C
.
.
For gaseous substances of concern, a tracer gas in a representative sample of the equipment at the intended
operating conditions, released at a rate determined by engineering analysis of the available gas flaw al the point
ofreleasc. (See Appendix 1.)
For liquid substances of coneeln, a substitute liquid, with an evaporation rate at the relevant temperature no less
than that of the substance of eoneem, in a representative sample of" the equipment at the intended operating
conditions. (See Appendix I tor the method o f determining the evaporation rate.)
For liquid substances of coneem, a tracer gas in a representative sample of the equipment at the intended
operating conditions. released at a rate determined using the method described in Appendix l for determining
the evaporation rate.
* For liquid substances of concern, a
tracer gas in a representative sample of the equipment at the intended
operating conditions, released at a l'ate determined using the method described in Appendix l for calculating an
estimated vapor generation rate from the properties of the substance of concern.
8.2.3.3 Tracer gas fugitive emission testing (see Appendix 2) may be used when instnlmentation for the substances
.v
of eeneem dues not have adequate sensiti ill. or when an instrument is not available for the substances of euneem.
Tracer gas testing should he used where testing with the substance of eeneern would present an unacceptable risk
.
{.e.g., system failure simulation with potential release of hazardous gas to atmosphere). See Appendix I for the
means of determining the tracer gas release late.
3.2.4 Sampling Time* for Measuring Airhomv Cfinwntruririns
Sampling For a lime period consistent with the
OEL. should be performed under operating. maintenance, or simulated failure conditions.
R.2.4,l For TWAS and STELs, integrated sampling tel' the GEL exposure period is preferred- Alternatively,
continuous sampling for the exposure period may be petfomted and the average concentration calculated from the
data. The average concentration should be compared directly to the performance t:1iteria in § 7 to detelmine
conformance to this document,
17
SEMI $6-0707 © SEMI 1993 5 2007
semi
EXCEPTION: I f the SME has a process cycle that is less than the exposure period of the TWA, sampling may be
performed for a complete process cycle and the average value during the cycle compared to the TWA to determine
conformance.
3.2.4.2 For Ceiling and IDLH limits, continuous sampling should be performed for the duration of the task. The
highest measured concentration should be compared directly to the pertbrrnance criteria in § 7 to demonstrate
conformance to this document.
NOTE 49: Each OEL is specified for an exposure period. For example, ACGIH specifies Time Weighted Average (TWA) limits
for an eight hour exposure period and Short Term Exposure Limits for a fifteen minute exposure period. When comparing
measured eoneentrations to (]ELs, the measurement period must be consistent with the period specified for the DEL. For
example, if an air sample for HCI is taken, an instantaneous air sampling method or a direct reading instrument should be used to
determine if there are peak emissions that exceed 25% of the TLV Ceiling level. For chemicals that have time weighted average
and short term exposure limits, sampling methods should be selected that will provide data allowing a comparison to those DEL
values.
NOTE Sl): For substances for which a TWA :- but not STEL or Ceiling limit, is specified, it is generally accepted that excursions
should be limited to five times the TWA as an instantaneous peak and three times the TWA for a maximum of thirty minutes per
shift.
8.2.4.3 Integrated sampling methods may be used when instantaneous sampling methods do not have adequate
sensitivity, or are not available tel' the substancetsl of concern. Where integrated air sampling is used, the sample
duration and locations(s] should be representative of the worst-case, realistic, anticipated exposure time and
locations.
8.2.4.4 The resulting cenccnlralinns arc directly compared
conformance to this document.
3.2.5 Id¢*n!ui¢.'a!ir1n :J Critical Exhaust ltentilrzrion Lorxuions
[O
lhc performance criteria in § 'f to demonstrate
- The equipment supplier should identify any critical
equipment locations for exlialllt ventilation, and quantify appropliate exhaust ventilation values for those locations.
Measurements should be made to identify optimal exhaust ventilation levels and confirm that safety criteria are
being addressed. Multiple validation and measurement methods may be needed.
NOTE 5 I: Process performance may be affected by exhaust ventilation values.
3.3 Sampling and .H
R .3.I The sample l
ventilation is used uupmuat
_
sentative of the worst-ease, realistic breathing zones (where exhaust
m
exposure) and potential ignition source locations (where exhaust
ventilation is used to mitigate fire risk).
NOTE 52: Air nr wipe sampling can be used to confirm that substances of concern are not being transported into unintended
areas of the equipment.
8.3.2 Equipment users typically use a throttling damper for balancing where the duct for a piece of equipment
connects to the rest of the exhaust ventilation system. Pressure and How measurements should be taken on the
equipment side of these balancing dampers.
3.4 Testing Prnr.*r*dur¢*.r and Methods
3.4.1 Validation nf Crfferl'a.1'r1r Evaluating Venfifatirzrz Designs fnr Prnvkering Erhausr Capture
3,4.1.1 An enclosure containing, or potentially containing, substances of concern can he visually evaluated to
determine if there is likely to be good airflow throughout. or if there are likely to be areas of low or no velocity.
NOTE 53: In some eases, a qualified professional will he able to determine, by visual inspection. whether the airflow patterns
provide appropriate exhaust ventilation to prevent formation of pockets of unaeeeptahle concentrations ofeontaminants. In other,
more complicated cases, empirical methods te-g.. velocity profiling or aerosol visualization) should he used to make this
determination.
8.-4.1.2 Computer modeling can be performed
to predict exhaust ventilation flow and substance-of-coneem
transport effectiveness in equipment by solving fluid meehanies conservation of energy and mass equations.
Modeling can he used during the equipment design stage or to improve existing equipment, Computer models
should be verified experimentally, using one or more of the methods discussed belowNOTE 54: Computer modeling is a commercially available service.
SEMI $6-0707 © SEMI 1993, 2007
18
semi
8.4.1.3 Velocity profiling within the equipment can be used to confirm expected airflows, capture velocity, the
direction of flow, and the velocity at various distances from the exhaust ventilation inlet. It can also be used to verify
that there are no locations of poor airflow within the enclosure.
3.4. I .3.1 Test Method - Multiple measurements using a velocity measuring device.. such as a hot-wire anemometer,
are recorded and minima and averages are determined.
8.4.1 .3.2 Aerosol Wsuolirotion - Visible effluent created by equipment such as de-ionized water aerosol
generators may be used to observe airflow patterns, the direction of flow. and the effect of distance on capturing
contaminants and to verify that there arc no areas of stagnation (aerodynamic "dead spots"I. Aerosol visualization
may also he acceptable tel' evaluating capture of vapors in open sul'face tanks, slot ventilation, coater bowls and
similar open or partially open systems.
8.4.2 Validation
of Conforinonce m SEMI $2 Pcnnissibie Concentration Criteria
S.4.2.1 When measuring airborne substances of interest directly, one should measure them using nationally or
internationally recognized test methods.
NOTE 55: NIOSH test methods (available at http:f!www.cdc.govfnioshMomepagehtmll may be used to test for certain toxic
materials.
3.4.2.2 Traeer gas fugitive emission testing tscc Appendix 2 for the test method) is a means of testing the integrity
of enclosures by simulating gas emission and measuring the etTectivcncss of controls, Testing until thel'e is a failure,
and then increasing the exhaust ventilation flow rate until the test is passed can be used to help minimize airflow
specifications.
8.5 Meosurwnents to be Uscdfor Validation
of instoiled
Equipment
3.5.1 As described elsewhere in this safety guideline, fugitive emission testing is necessary for the design
verification. The sufficiency of exhaust ventilation can be verified by measuring volumetric flow (e.g., by use of a
hot-wire anemometers after equipment installation, once the enclosure requirement has been established during
design velifiealion.
3.5.2 Once capture has been verified by measurement of fugitive emissions (during design validation).
measurements should be taken at specific openings l a k e - u p air sluts, accessways, or windows. etc.) to establish the
minimum How velocity at these specific openings while controlling tilgitive emissions. Record the position of
covers, doors, dampers, valve handle openings. le., and flow restrictions (such as fluid levels in vessels which
exhaust ventilation air serves or through which it flows] at the time of the exhaust ventilation tests so that the test
conditions can he duplicated.
NOTE 56: These velocity measurements are necessary to provide a means of verifying exhaust ventilation performance which is
more rigorous than simply relying on the equipment exhaust ventilation being set close to the suppliers' specifications at point of
connection.
NOTE 57: Care should he exercised to assure that the readings are the result of the exhaust ventilation flow and not general
room turbulence. Vapor' visualization can help determine if the velocity readings are due to turbulence of' if turbulence could
adversely affect capture of containinauts.
3.6 Cbrrecrirm Factors
3.6.1 Specifications should he stated in Standard Air Density tkgfmfl of' lbftl-'-1), as defined in fndusrri'uI
ifetrrilririorill. If the measurements are of non-standard air, state the correction factor for density. Useis should
colTect field balancing measurements taken above 600 meters i2000 fectl elevation before comparing them to
suppliers' specified data. Additionally, the data must be corrected, by the supplier, to sea level if they were
measured above 600 meters elevation.
8.6.2 Flow measurements taken at other than standard air temperatures 121.l°C {700F}} in the duct should be
corrected to standard conditions.
I I ACGIH. Indusrrfuf Venrifuriun, A Hanna! of R¢='»:"ormn¢='nded Prtwrice. 1330 Kcmp-cr Meadow Drive, Cincinnati. 'UH 45240-1634, USA.
http:.-"."www.al:gih.org, Library of Congress Catalog Card Number: 62-12929.
19
SEMI S6-D707 © SEMI 1993, 2007
semi
8.6-3 Corrections for altitude and temperature should use the following relationship:
Mohr = tnf¢/nn(294_3/T,,li D) or COM = tM~)(S3WTRHD)
where :
M.f//r
Standard cubic meters per hour
m.¢»'hr
Measured cubic meters per hour
TK
II
Measured tcmpcral-ure in K
II
Measured temperature in degrees C
II
Altitude density correction factor see Table 1)
II
Standard cubic feet per minute
II
Measured cubic feet per minute
II
Measured temperature in degrees R (TR = TI.- + 459.71
II
Measured temperature in degrees F
To
D
COM
fem
To
TF
{.TI»;
= TC + 273.2}
Table 1 Density Correction Factors
Airimde
Density Cvrrecrirm Fm'!r:r
sea level
l .00
300 m 11000 fi)
0.06
600 m [2000 in
0.93
900 m 13000 in
0.89
II
1200 m {4000 few
0.86
1500 m {5000 few
0.83
In
R.6.3.1 Where air temperature is less than 37.8DC {|O0DF}, no correction tor humidity is necessary. For temperatures
above 37.8°C (|U0oF}, correction for humidity should be made when moisture content is greater than 2% waterfdly
air. Refer to Industrial' Ventikiriorr, a Manual of Recwitmrended Practice for further details i f necessary to correct for
humidity.
NOTE 58: lt is not expected that these conditions would exist in a user facility environment.
8.7 fnsfrurnenrs
3.7.1 The measuring instruments used should be capable of measurement in the range of interest and in good
working condition and current calibration (i.e., calibrated as recently as, and in the manner, specified by the
instrument manufacturer).
NOTE 59: The description, operation, maintenance, and limitations of instruments used to measure exhaust ventilation pressure
and flow rates is covered in Chapter *J of hidusrrial' Veritifaririri, a Manual of Recoininended Prar'ri»:,'e. A companion reference is
Procedural Standards for Testing Adjusting Balancing o f Environmental Systems
II'
8.7.2 The accuracy of the instruments should be included in the test repoit.
8.3 Munagernenr
of Fire* Risk
/ of the LFL at potential ignition sources should be conducted using the method described in
8.8.1 Testing for 25%
Appendix 4: Test Method: Air Pauein Assessment for Flammable Sources.
NOTE 60: lt is recommended that one begin testing at a minimum airflow suftieient to dilute the flammable gas or vapor to 25%
of its LFL at the enclosure outlet.
12 National Environmental Balancing Bureau, 1335 Piccard Drive, Rockville, MD 20350-4340
SEMI S6-DTD? @ SEMI 1993, 2007
20
semi
8.8.2 The following hie1archy should be used for testing and validating that airborne concentrations of flammable
materials are below 25% of the LFL.
3.8.2.1 Direct reading instruments arc the prellen°ed method for measuring flammable gasesfvapers when they allow
measurements at the potential sources of ignition,
3.8.2.2 Where direct reading instruments are not available for the substances of concern in question or do not allow
measurements to be taken at the potential source of ignition, tracer gas analysis is an acceptable method.
8.8.2.2.1 An equivalent release rate and velocity should be detelmined (see Appendix II.
S.8.2.2.2 The tracer gas should be released at potential leak points.
S.8.2.2.3 The samples should be collected at the potential sources of ignition.
3.8.2.2.4 The results should be reported in terms of percent LFL of the substance of concern in question.
NOTE 61: In the absence of such tests or i1` adequate reduction o1` flammable gas cannot be achieved, special elect1ic8l designs
or other controls ie.g., LFL detectors, approved purging) may be required to reduce the probability of ignition. Removal of
potential ignition sources is a means of reducing the exhaust ventilation requirement.
NOTE 62: If there is doubt about whether exhaust ventilation achieves reduction to below 25% of the LFL, gas or vapor,
monitoring can be installed and interlocked to shut off either the potential ignition sources or the source of fuel. Removal of fuel
sources is a means of reducing the exhaust ventilation requirement.
NOTE 63: Some jurisdictions require a monitoring point in the duct set al l0% LFL; this should not be confused with the:
criterion in this document for less than 25% near potential ignition sources.
3.9 Eftieieney and optimization should be assessed by comparing the measured volumetric airflows to the criteria in
§ 7.
3.10 Testing of AEV should he conclueted to verify that the concentrations of the substances of enncem meet the
criteria slated elsewhere in this safety guideline.
8.10.1 Measul'emellt of capture velocity should be taken at the furthest point of contaminant release from the point
of contaminant capture {e.g., face of the hood Ur exhaust ventilation duet opening). Measurements should be taken
with an anemometer.
NOTE 64: Confil'mation of capture may he made using aerosol visualization methods. The almsewed performance may depend
cm the airflow conditioiis in the room iii which this is pczrfarlmed.
R.l I EF,1uip.rn-rn! Test Vu lidrefiun Reporting - Equipment exhaust ventilation testing pertbrmcd to determine
conformance to the exhaust ventilation criteria in SEMI $2, should be reported as specified below:
S. I I .l All test measurements should be performed based on the test methods specified in this section and in the
appendices.
8.11.2 Each result measured during the test should be provided with its tolerance.
-
8.1 1.3 Equipment Infonriutirrn
Describe the unit being tested by equipment supplier, model number, and serial
number to provide identification.
S. l l .4 Equipment' Cotu'ig ration - Describe the configuration of the equipment including the size and placement of
air intakes. doors. panels. outlets. and factors affecting exhaust ventilation flow. Descriptions may include
photographs or drawings when they help the reader visualize the equipment configuration.
3.1 1.5 Equipment* Proce.r.s Recipe and Hazard frmrntnrion -
Provide the process chemical name, supply
concentration, maximum flow late (both available at potential leak points and required for anticipated processes),
LFL. and OEL for each substance ofeoncern used within each enclosure being tested.
3. l l .to Erhrzust Venrilatforz Test Method we' Equipment Conafifion fryirinnurion
3. I I .6. I Provide dale, location of testing. and persons performing lest.
3. I I ,6.2 Describe test methods.
R. I I ,6.3 Provide reference to recognized test methods used.
21
SEMI $6-0707 © SEMI 1993, 2007
semi
8. I I .6.4 Identif
test equipment used and the date last calibrated.
8.1 1.6.5 Where sample media or tracer gas are used, identify expiration dates, calibration status, unique identifiers
such as lot numbers, and any other pertinent information.
8. I I .6.6 Describe any dcvialiens from recognized lcsl melheds.
3. I I .6.'7 Describe test conditions affecting results.
3.1 1.6.8 Describe test location environmental conditions that may affect results (temperature, humidity, altitude,
room airflow).
3. I I .6.9 Describe the exhaLLqt ventilation operating conditions during each test-
?».1 1.f».10 For fugitive emission testing, describe air velocity outside the enclosure behlreen the sample point and the
enclosure surface, air velocity at the sample point, the location of sample point{s}.
8. I I .6. I I Describe all test points.
8. I I .6.12 Identify location of exhaust ventilation flow measurements and measurement method used (e.g., pilot
tube, manometer. thermal arlemometerl.
li*».1 1.7 Exhaust Ventilation Test R:'suh.¢ and Crmc.'h:.rfrm.r - Present all results and clearly identity pass or t81il status
and the criteria used to determine status.
9 Minimum Information to be Provided to End User
9.1 The material in §9nf'th.il
lllnnild b-nuludtu
to this document
uh ausl
9.2 Equipmentr E.,,n¢ll,,
specifications and i
vcntilalion
to the cvalualur
and to the end user.
9.3 D¢*.':cri;Jtifm :Ethe 8.:1.s'i.s'jbr Erfaausr Venrilatfnn Do
9.3.1 The documentation should describe the release rates for the substances of concern that were used as the basis
of ventilation design. The description should ine' " the ulnginnr.
amlglnniering controls on which the designer relied for flow
limitation (soc § 7.2).
9,4 Arrfmzx :had Enxura? rfxur Equiprruw! is in
(I
I
*}.4.1 Describe all automatic actions the: equipment takes to ensure it is in a safe condition upon less of exhaust
ventilation.
9.4.2 If the equipment can be configured to take different actions upon loss of exhaust ventilation, describe how to
determine which actions arc appropriate for the installation and use of the equipment and how lo configure the
equipment to take those actions.
9.4.3 Describe the appropriate responses by personnel to the equipment having placed itself in a sate condition,
including how to reset the equipment when exhaust ventilation is |'esto|'ed-
9.4.4 Identify appropriate actions, if any, to be performed by personnel in the event of extended facility exhaust
ventilation failure te.g., power failure greater than 15 minutes) to ensure protection of people and prevent damage to
equipment and facilities.
9.5 Iqffarmatirzn that D¢'.1.'cribe.c the Ejffuimf
9.5. I The supplier should provide the user with a list of process chemicals or by-products that could he expected in
the exhaust ventilation stream when the equipment and the users' exhaust ventilation system are operating within
design specifications. This may be estimated by stoichiometric or mass-balance calculations, or based on the results
of exhaust ventilation emission characterization testing based on the appropriate conformance criteria in SEMI $2.
InfOrmation typically provided includes percentage by weight or volume) and physical state (gas, liquid or solid).
NOTE 65: SEMI F5 prcwides information regarding eMuent treatment.
9.5-2 The normal operating and maximum and minimum temperatures of the exhaust ventilation stream when it
enters the facility exhaust ventilation system should be documented for the equipment supplier's baseline processes.
SEMI S6-0T07 @ SEMI 1993, 2007
22
semi
9.6 hfforrnariort :had Describes aha Facflin' Requiremettts
9.6.1 The equipment may require different exhaust ventilation flow
Ol'
pressure during the process cycle than in
standby or maintenance modes. The supplier should provide specifications for normal operating mWe demands,
peak demand, and any other demand level required tor safety. The normal, peak. and other critical safety condition
demands should be considered in both the system design and the field balance. Information should be based on a
twenty-four hour, continuous period of operation of the equipment. (Extrapolation in time is generally acceptable if
the method used is well-documented and can be duplicated.)
9.6.2 Spfdtit-caririn Tube: - The table provided in Related Information 6 is the proforrcd method to communicate
those specifications in the documentation.
9.6-2.1 The measurements to obtain these specifications should be performed based on the test methods established
in the appendices.
9.6.2.2 Each specification should be provided with its acceptable range of tolelance.
9.6.2.3 Thusc specifications that are not applicable lo the system/equipment should be included in the
documentation and marked as "NIA"
9.6.3 Exhaust ventilation Specification Design Drawing. The exhaust ventilation specifications should include
design information on the equipment exhaust ventilation system in a drawing of' graphical lOnnat. The drawing
should include the exhaust ventilation connections with critical dimensions. established set points, and the location
of the measurement points used to develop the specifications.
9.6.4 Tlle supplier should provide the duct size (the inside diameter of the exhaust ventilation connection from the
equipment] and any other dimensions needed to design the connection of the exhaust ventilation system to the
equipment.
9.6.5 The supplier should specify the minimum volumetric flow rate required to control chemical emissions based
on chemical emission testing. Refer to the appendices for guidance to measure exhaust ventilation flew rate,
9.6.6 The supplier should specify the minimum static pressure required to control chemical emissions based on
chemical emission testing. Refer to the appendices tor guidance to measure exhaust ventilation How l'ate.
9.6.6.1 The supplier should describe the location at which this static pressure measurement was taken.
9.6.6.2 The location should:
.
provide reproducible measurements,
I
he on the SME (e.g.. facility exhaust ventilation collar, wall of a ventilated enclosure), and
I
be accessible to the user.
NOTF. 66: The supplier cannot assure that the duct configuration of the installed SME will he identical to the conditions under
which the exhaust ventilation was originally tested. The intent is to provide a measurement point that is not affected by static
pressure losses created Br the configuration o f the duct work downstream of the measurement point. The static measurement
point may be taken in a turbulent flow zone i f the readings are reproduciblE.
9.6.7 The equipment supplier may also specify exhaust ventilation requirements for reasons that do not relate to
personnel safely leg., process critical specifications). These should be clearly documented as not being related to
safety, se that the equipment user can determine what actions to take fer these types of alarms.
NOTE 67: The decision. by a user, to mix exhaust ventilation streams that are segregated by the equipment supplier should be
based on the consequences of mixing those streams. Consequences may include formation of hazardous by-products. or
maintenance problems {e.g., unwanted deposition of solids iii ducts or environmental concerns (e.g.. visible plumes. Contrarily,
the segregation of effluent streams call lead to uiidesirahle consequences, such as accumulation of reactive CVD residues.
9.7 In.forma!i'o.*1 Dewribing How to Adjust the Erhausr Venn'l¢n'ion and Con jinn its Proper Operation
9.7.1 The supplier should provide a scale drawing of the equipment exhaust ventilation system showing where users
are to adjust exhaust ventilation.
9.7.2 The required relationships among exhaust ventilation settings of various parts of the equipment and the
consequences of failing lo maintain those relationships should be identified.
23
SEMI $6-0707 © SEMI 1993, 2007
semi
NOTE 63: In some equipment. a failure to maintain the relationships. even if the specifications for each part of the equipment
are met, can result in undesirable behavior. For example, the relative exhaust ventilation of two parts of the equipment may need
to be maintained in a certain range to prevent hack streaming through liquid chemical secondary containment.
9.7.3 The supplier' should identify the points of measurement for all duct exhaust ventilation. Information should be
given to locate the point of measurement by providing the distance from the facility exhaust ventilation connection
or other fixed point described in the documentation. Altcmatively. a diagram may be provided indicating the exhaust
ventilation connection with the measurement locations. Refer to the appendices for recommended locations of
exhaust ventilation measurements in ducts.
9.7.4 The supplier should describe how the exhaust ventilation velocity was measured across the face of an
operation or maintenance aecessway and should state what velocities were found. during the validation tests
described in § 8, to provide adequate performance. Refer to the appendices for the method for measuring exhaust
ventilation face velocity.
9.7.5 The supplier should describe how the exhaust ventilation velocity was measured at the point of potential
chemical emissions resulting from normal operation tc.g.. open top of chemical bal hl. or maintenance tasks te.g.,
filter housing or pump connections), or failure conditions te.g.. leak or spill at fittings into secondary containment).
Refer to the appendices for guidance to measure exhaust ventilation face velocity. The supplier should state what
velocities were found, during the validation tests described in Ii 8, to provide adequate performance.
9.7.5.1 User knowledge of the exact configuration of the ventilated enclosure including location, size, and number
of air inlets and other openings is essential for verification that conditions of any testing (such as tracer gas analysis)
are duplicated on the equipment as installed in the field. Equipment data used to establish exhaust ventilation
specifications should reflect the equipment's environmental conditions anticipated when installed (e.g., bulkhead
mounted equipment is supplied with data for a bulkhead installation).
9.7.6 The supplier should describe equipment environmental conditions {e.g.. presence or lack of laminar airflow in
the room, velocity of laminar flow} that may affect the exhaust ventilation measurements.
9.7.7 If detectors are not provided by the supplier, the supplier should document the optimum location to detect a
leak.
Iilnihannilulure and other components of the exhaust
9.7.8 A list of materials used in the eonstrudilllll
ventilation system should be included in the I
the chemicals that the equipment is design
l equipment supplier can list
E consult with the equipment
I
supplier before using chemicals that are not ind
9.7.9 Information for post-installation and periodic exhaust ventilation cheeks should be provided in the system
documentation.
9.8 The supplier should explain the rationale by which delays in the interlocks that respond to loss of exhaust
ventilation pressure or flow were determined or, if no such delays are incorporated in the equipment, the rationale
for not including them. The explanation should include a description of the risks associated with increasing the
delays.
NOTE 69: Decreasing delays increases the probability that typical variations in facility exhaust performance will result in
response of the interlocks. Although this does not increase the risk of personnel to exposure, it may result in increased
interruptions of operation of the equipment without significantly reducing the risks to personnel or equipment.
9.9 The supplier should state that changing any parameter of the systems in the SME {e.g.. changing exhaust
monitoring set points, working with portions of the enclosure removed) may cause an unexpected condition.
SEMI $6-0707 @ SEMI 1993, 2007
24
semi
10 Related Documents
10.1 SEMI Srundurds
SEMI $5 -
Safety Guideline for Flow Limiting Devices
10.2 ACGfH®
ACGIH, hrdusfriuf Wntifutinn. A Muumuu! qfRwwmmwadrrI Pru{.'!ir1'. 1330 Kemper Meadow Drive, Cincinnati. OH
45240-1634, USA. I1ttp:h*xw»'w.acgih.org; Library ofCongl'ess Catalog Card Number: 62-12929Semiconductor Exhaust Ventilation Guidebook
103 ASTM Standards
ASTM E 260
Practice for Packed Column Gas Chromatography
IU-4 NFPA Standards
NFPA 13 - Standard for the Installation of Sprinkler Systems
NFPA 3 I S - Standard tor the Protection of Semiconductor Fabrication Facilities
I(}-5 Senrfcnnducror Enviromnerzmh Safety and Health Assmciurinn
Taminini, Francesco and Antonio C. Braga, "A New Perspective on the Behavior of Silane Leaks in Ventilated
Enclosures-Implications fur the Design of Protusclion Methods" SSA Journal 'V'ol.l I - Winter 1997, pp 21-36.
10.6 SMACNA (Sheer Meta! and Air Crfrufffirfnirrg Conrrucrurs' Narinnaf Association. hrc. )
la
HVAC Systems Duct Design
HVAC Systems: Testing. Adjusting, and Balancing
13 SMACNA {Sh1:¢t Meal and Air Conditioning Contractors' National Association. Inc). 8224 Old Courlhousc Road. Tyson's Coma. Vicnna.
VA 22183. USA; Telephone: T03-790-08911
25
sem
SEMI $6-0707 © SEMI 1993 1 2007
I
*.
APPENDIX 1
DETERMINATION OF GAS AND VAPOR GENERATION AND RELEASE
RATES
NOTICE:
I
Pl'4JCCL LITCS
The matelial in this appendix is an official pan of SEMI $6 and was appl'oved by full letter ballot
on April 25. 2007 by the global Environmental. Health & Safety Committee.
A1-1 Releases from Disconnected Gas Piping
A I - I . l Flow if a straight tube may be calculated if the tube charactelistics, as well as the upstream and dov»mst1'eam
pressures, are known. In the following analysis. the upstream {dlive sides conditions have a subscript of 1, w hill
the downstream {ambit=::nt} ccanditions have a subscript o f f .
Flow Direction
;*»
P .P
1
1
Jr
+D I
I
-c
L
11-
.4
Figlllll
-1
Al-1.2 Solve for the 1
values into Equation A.
I
substitute these
flow rate tor the
Equatiuri
II
K
J
I _,f
L
4
+ln PI
Pa
f D
pl
Hr
f*al
p,
PA
Alf~p.»@~@'.2
Q
(Al-I)
2
1
i
=:
P~J
PJ
tracer gas uS in
Po ' Fu
IAI-21
T"
(Al-Bl
wlf
1A1-41
M gas
where:
density of gas flowing through straight tube at dovmstream (ambient) conditions
PU
[ w e . Refer to Table
A I -1 for hazardous gas densities.
square of upstream Mach number (dimensionless)
II
P
ratio of gas mixture speeifie heat values (ep/cv1. typically 1.4 for gases ofeoneem (dimensionless)
II
MI
II
x
Pressure, absolute [dynesfcm7ll]
14 Shapiro. A.H.. "The Dynamics and Thrnrracfynarrrics of COMPRESSI8LE FLUID FLOW. " Vol. I. pp. I R2-183. Thc Ronald Prcss Company,
New York. N.Y. USA.
SEMI $6-0707 @ SEMI 1993, 2007
26
semi
NOTE l: One ahnosphere ¢:otTespunds to LGI
>(
m" dynesfcml. which is approximately l4.'f psi.
4.f
0.02 surface roughness paiameter for smooth pipe (dimensionless)
L
Length o f pipe [cm]
D
Diameter of pipe [cm]
w
Mass Flowrate [Ysee] of gas Rowing in straight tube
A
Cross-sectional Area of Flow Line [em2]
Q
Volume Flowrate [literffsee] of gas
v
22.4 [Iitertmole] Molar Ideal Gas Volume
M
¢l.!lcl.S
Molecular Weight of Gas [gfmole]
Table A1-1 Densities and Molecular Weights Of Hazardous Gases
Hazardous Gas
Standard Densfry '#*r:IrE"''l`***f»
as 10/.3 RFC. 2:1 'C ( I
Acetylene. C2H2
1.09
x
IU
x
m"
Ammonia, NH;
7.09
Arsine. ASHY
1.42 3.3 10
Boron trichluridc. BCI;
4.35
3
3
x
nr"
J(
3
Boron triIIuoride, BF;
2.1333
Carbon Monoxide. CCI
1.16
3-c
Chlorine. CI;
2.97
x
Dihoranc, B2H,.
I_l(, x
3.c
Dichlorosilane. SiH8(II2
4.18
Dimcthylaminc. iCH.},NH
I .33 x
lo
26.04
17.03
77,95
I 17.17
67.8
lo"
lu-3
70.91
IT'
27.69
10
3
nr"
{`icmlanc. GQH4
3.131 10
Hydrogen. H;
8.35)<I0
x
Maiecidfar Weigh! [gimme]
and, ?0"F)
23.01
101.UI
45.03
3
76.63
5
2.02
10-4
16.04
Methane. CHO
6.76
Nitrogen TriI1uoride, NF;
2.95* 10
3
71.00
Nitrous Oxide. N20
1.84 kg 10 1.
44.01
Ozone. 03
1.93
x
47.98
Pho:-igcnc, COCI;
4.1 ex 10
10 "
3
93.92
34.00
Phosphine. PH;
1.42
x
10
3
Silane. SiH4
1.34
x
10
3
32.12
Silicon Tetrafluoride, SiFt
4.34
x
10
3
104.08
A1-2 Deposited, Adsorbed, or Absorbed Materials
Al-2.1 Release and generation from materials deposited, adsolbed or absorbed on equipment surfaces depends on
the processes by which the matelials came to be on the surfaces, the nature of the substances of concern, and the
conditions (including atmospheric exposure or added substances) under which release or generation occurs.
Al-2.2 Nu reliable models are known for predicting the release or generation of substances of concern from such
sources. If the adequacy of the exhaust ventilation is to be tested by simulating a release of' generation, the
substances of concern and their rates of release or generation should be measured, under the foreseen conditions of
release or generation, on a representative sample of the equipment that has been operated and maintained as its
supplier instructs.
27
SEMI $6-0707 © SEMI 1993, 2007
semi
A1-3 Generation from Solid Substances of Concern
A l - 3 . I If the adequacy
o f the exhaust ventilation is to he tested by simulating a release or generation, the
substances of concern and their rates of release or generation should be measured. under the foreseen conditions of
release or generation, an a representative sample of the equipment that has been operated and maintained as its
supplier instructs.
Al-3.2 If such measurements are not feasible, the release or generation should be determined by measuring the
concentration of the substanee{s) of eoneem in air Flowing past the exposed surface of the solid substance of concern
under the temperature, pressure, and How conditions that are foreseen during operation, maintenance, and failure of
the equipment.
A1-4 Vapors from Releases of Llquld
Al-4.l Releases of liquid that do not result in fomiing a liquid pool {i.e., the substance of concern is convened lu
vapor as rapidly as it is being released),
NOTE 2: This method assumes that the vapor behaves as an ideal gas {i.e., the general gas law, PV =nRT applies). Equations
Al-5 and Al-6 are derived from the general gas law.
Al-4. I .I This method is also used for liquids released as aerosolS.
A I - 4 , l ,2 This method may he used for liquid releases that do term liquid pools.
NOTE 3: This method will overestimate the vapor generation from releases that fo.rm liquid pools
Le
Al-4. l .3 The vapor geneialion rate is calculated from Mu vi
G=
Vliq
re D
rate of the liquid by:
xT:R
(Al-53
G
vapor generation rate [atmospheric Iitersfmilmte]
Vffq
liquid release late [milliliters minute]
Din;
liquid density [gramso'milliliter]
MW
molecular weight of the substance of cottccm [gramshuolc]
T
II
tn:mpc111\ur4: of the vapor [Kelvin]
II
where:
0.08021 [atmospheric litersflmule KI]
R
AI-4.l.4 Tlle vapor generation rate is calculated from the mass release late of the liquid by:
G = M Hr; x T
X
R
MW
1AI-63
where::
G
vapor generation rate [atmospheric litersfmillute]
Mfiq
liquid release rate [g1'a111s.:'minL1te]
MW
molecular weight of the substance of concern [grams/mole]
T
temperature of the vapor [Kelvin]
R
0.08021 [atmosphelits Iitem'{mole K}]
NOTE 4: The temperature of the vapor may be considered to be the ambient air temperature in the enclosure. Unless the
temperature of the enclosure is deliberately controlled to some other value, it is recommended that 20<*C {68OF} be used in this
calculation.
SEMI $6-0707 © SEMI 1993, 2007
28
semi
AI -4.2 Vuporfrom Pools Qj"'iquid
Al -4.2.1 App iicahii!flajv
AI-4.2.1. I This method applies to pools of liquid that are open to exhaust ventilation during normal opelation or
maintenance.
Al-4.2.1 .2 This method applies to pools of liquid that result from releases caused by failures.
Al-4.2.2 Unlcss performing such a test would present unacceptable risk. determine the generation Cr release rate,
per unit area, br a pon] of the substance of concern using the following method.
Al-4.2.2.l Expose an open pan of the substance o f concern to the liquid temperature, air temperature, pressure and
flow velocity to which the pool would be exposed in the equipment.
Al-4.2.2. I .I The length of the pan in the direction of the airflow must be at least as great as that dimension of the
pool.
Al-4.2.2.l.2 A surrogate material may be used if the target chemical has hazardous properties which make it
unsuitable tor the test- The sulTogate material must have at least the same evaporation rate at the temperature of
interest as the target chemical.
NOTE 5: An understanding of the conditions experienced in various types of semiconductor manufacturing environments is
essential tor designing the test conditions. A pan of chemical located in a small tightly sealed box which allows the chemical to
quickly achieve equilibrium vapor pressure would not be a good test for equipment where the leak will take place in a large open
environment. A pan of chemical located in a high velocity airflow which causes unrealistically rapid evaporation would not he a
good test for equipment where the leak will take place in an enclosure with low exhaust ventilation rate.
AI-4.2.2.2 Calculate the surface area of the liquid pool in the pan.
AI-4.2.2.3 Add a known volume (mass) of test liquid to the pan.
Al-4.2.2.4 Nolc lhc time at which the chemical was added lo the pan.
Al-4.2.2.5 Nolc lhc time at which approximately half of the liquid has cvaporalcd.
Al-4.2.2.6 Measure the volume {masse of the remaining material.
Al-4.2.2.7 Determine the volume (mass) of chemical that has evaporated per minute and unit area.
A1-4.2.2.8 Estimate the volumetric evaporation rate lwfql or the mass evaporation Tate {MIiq) by multiplying the
result of the previous calculation by the surface area o f the pool in the equipment.
A1-4.2.2.9 Calculate the vapor generation rate (Of using one of the equations above.
A]-4.2.3 If the risk of performing the generation of' release rate test is not acceptable, estimate the release rate using
the following model.
Al-4.2.3.1 For substances of concern with vapor pressure of more than 35 tolT at the greater of the temperature at
which the liquid is released or the temperature of the surface on which it would collect, use the method described in
1I Al-4.l for evaporation at the release l'ate. Alternatively, the vapor release rate in the equipment may be measured
indirectly, such as by measuring the concentration in the exhaust ventilation stream or the mass loss over time from
a liquid pool.
AI-4.2.3.2 For suhstanees of eeneern with vapor pressure of 35 terr or less at the greater of the temperature at
which the liquid is released or the temperature of the surthee on which it would collect, use the model derived by
Hummel, or al. 152
5.205 x 10
X
(MW}n.:-233
Qvup
K
VP )< (1~..=IMW + 1.-~'29}0~;5
7..ru0005
15 Hummel. All'H:rt A., Karl O. Braun. and M. C'athc1'inc Fchrcnbachcr. "EvalJo1'ation of 8 Liquid in
Volume 57, ppl5l\J*-525. June 1906.
29
8
x
Vcrfr
LxP
Flowing Airstream". AIHA Jnumal,
SEMI $6-0707 © SEMI 1993, 2007
semi
where 1
vapor generation rate [g1ams;'(cm1°mi11)]
Qw,
MW
molecular weight of the substance ofeoueem [glams»,'mule]
1P
vapor pressure of the substance ut` eoneem at the liquid surface temperature [millibar]
Var?
velocity of airflow over the liquid surface [enni'see]
J'
1Al-'U
Tact
surface temperature of the liquid [kclvin]
L
linear dimension of the liquid surface in the direction of airflow [in cm]
P
overall pressure at which vapor is generated [atmospheres] {This is the air pressure at the surface of the
pool and is usually equal to: l atrnosphel'e.}
NOTE 6: It is recommended that the greater of the telnpel'ature at which the liquid is released or the tenlpe1'ah,1re of the surface
on which it would collect be used as the surface temperah.n'e of the liquid.
or:
:.: (MWl0,R33
45,939 x 10
Q1vrIp
';-:
T
up x Il..--'mw + l,.-~'2-Q)u.25
pa
Vruir
[LGS
LX P
:ruff
lAI-sT»
where:
VP
vapor pressure
|
[ton]
concern at 1
ihepoollrea
Al-4. 2-3.2. I Multiply the generation or release rate |
release rate for the pool.
Mmvzp
=
Quup- X Afiq
to calculate the generation of'
IAI-9;
where:
Mm'up
vapor release rate [gramsfminute]
AIIL]
surface area of the liquid [cm2]
Al-4.2.3.2.2 Calculate the generation or release rate using:
G
M rug:
X
up X
R
MW
(Al-10)
where:
G
vapor generation rate [atmospheric Iitersfminutel
MW
molecular weight of the substance of concern [gtams.'mole]
7'-np
temperature of the vapor [Kelvin]
R
0.[}S021 [atmospheric liters:'lmole KI]
Al-4.3 Vapor from 8ubhler -
Assumes vapor behaves as ideal gas, and that the vapor reaches saturation '.-'apr
pressure in the canicr gas.
Al-4.3.1 The vapor genciation rate is calculated from the carrier gas flow and the conditions in the bubbler by:
SEMI $6-0707 @ SEMI 1993, 2007
I0
semi
V
_q!)L\
- Vr.qn.¢ :-c
.soF.
L.
.bu!5»
where :
VJ-nr
substance of Cl}I'ICB'l'l'1 vapor flow [liters minute]
(Al-ll)
Vqqu.-s'
Cahier gas How [litershninute]
up.
substance of concern vapor pressure at the bubbler temperature
Pbub
pressure within the bubbler
NOTE '.*: Equation A l - I I was developed by the originating task force as follows: Pi'Sit..b is the sum of the partial pressure of the
ean'ier gas within the huhhler and VP., (assuming that the SOC saturates the catl'ier gas). Therefore, the term (PM, - V P ) is the
partial pressure'e of the carrier gas in the hobbler. The telm in [square brackets] in Equation A l - 1 1 is. therefore the ratio of the
pressure of the SOC to that of the carrier gas within the hulalaler. Assuming that the gases behave as ideal gases, the ratio of
pressures is the same as the ratio of volumes. Therefore, multiplying i i , by the term in squal'e brackets results in v .
NUTE 8: This assumes that the carrier gas is ineit. If the catTier gas itself is a substance of concern Les-. hydrogen) the hazards
of the calTier gas also need to he addressed.
A1-5 Releases at Materials that Can React with Air to Produce Substances of Concern
Al-S.l This subsection applies to materials (which may not be substances of couceml that react with air (including
wider water vapor in air) to liberate substances of conccm.
Al-5.2 If the released materials are substances of eoneem. then the release of the material itself, as well as the
products of its reaction with air, should be considered.
Al-5.3 Unless the reaction rate is known, assume that there is sufficient water and air available to cause the
substance of concern to react completely and that the reaction rate o f substance of concern is the same as the rate of
rclcasc.
Al-5.4 Caleulale the substance of eoneem generation rate. G. from the appropriate one of the following formulae:
AI-5.4. I If the released material is a gas:
G
M 104: xifgm
( A l - 1 2 .)
where :
G
= substance of concern generation late, in atmospheric liters minute
M.wc'
=
moles of substance of ecmeem generated per mole of released malelial
Vi
=
gas release rate in atmospheric litersfminule
NOTE 9: For example dichlorosilane {SiH8CI2} reacts in moist air to form two molecules of HCI for each molecule of S11-IICI2.
Therefore, m,,..- for SiH31'Tl3 is 2 and HCI is generated at twice the Tate as the volumetric release rate of SiH3Cl;. As stated in
1 A1-5.2, both the hazards of SiH1Cll; and of HCI must be considered. although the release rates should not be added, as a
molecule of SiH1Cl; ceases to exist upon creation of HC] from ii.
A 1-5,4.2 If the released material is a liquid and the volumetric release Tate is known:
G-
M
.'r¢JI;'
: Viifrx Dfw:-(Tx R
MW
(Al-l3`}
where:
G
M
substance of concern genelation rate [atmospheric litersfmillute]
.a'rJc'
moles of substance of concern generated per mole of released material
31
sem
VI,Iq
liquid release rate [milliliters/minute]
DIn
liquid density [gramsfmillililer]
MWHQ
molecular weight of the liquid [gramsfmole]
SEMI $6-0707 © SEMI 1993, 2007
I
01
T
temperature of the: vapor [Kelvin]
R
0.08021 [atmospheric litc:rs'(mole K)]
NOTE IU: The term ID",/.*l»fWl,,,l converts the release rate from [millilitersfminulel to [moles¢*'minuIe]. The term [T
` Equation Al-I2.
the release rate from [moleshninute] to [atmospheric lite1's»'minute]. m.,re has the same role as in
1-c
R) converts
»
A 1-5.4.3 If the released material is a liquid and the mass release rate is known:
G=
M' .ym
1
\
M HI' x T D-1 R
'
(Al-14)
myn
where :
G
M
substance of concern generation rate [atmospheric liters minute]
.'ll'.ll"
moles of substance of conccm generated per mole ofrcleascd material
Mfrs
liquid neleasc rate [gtamsfrninute]
Mwlgq
molecular 1 1 ¢ a g b n 1 l 1 ! ' 1 m m h l p je]
T
ICITIPCTEIIIUI
R
0,0302 l
am
nr
SEMI $6-0707 @ SEMI 1993, 2007
32
semi
APPENDIX 2
TEST METHOD FOR DETERMINING FUGITIVE EMISSIONS BY USING
TRACER GAS
NOTICE: The matelial in this appendix is an official pan of SEMI $6 and was approved by full letter ballot
procedures on April 25, 2007 by the global Environmental, Health & Safety Committee.
A2-1 Purpose
A2-l.l This test method is intended to test the containment ability of a local exhaust ventilation system within an
enclosure under the equipment supplier's specified operating conditions. Thus, lest data obtained by means of this
test method apply only to the exhaust ventilation conditions that existed within the enclosure during the testing.
Extlapolation of the test data to other exhaust ventilation operating conditions is not usually valid.
A2-l.2 Use of this test method requires knowledge of the principles of gas analysis as well as flow and pressure
measurement, gas analytical instmmelltatifm, and gas sampling techniques.
NOTE l: An acceptable enclosure does not imply a safe condition tor routine equipment operation with a leak or a tubing fitting
failure. An acceptable enclosure is one that will contain potential worst-ease leaks in an emergency, non-routine situation. The
fact that an enclosure is acceptable does not imply that the equipment should remain in operation when a hazardous gas leak has
been detected.
A2-2 Summary of Method
A2-2.l A test is performed by releasing tracer gas at a constant How rate {e.g., to represent a release to the
enclosure under normal operation
of'
to simulate a worst-case leak) within an enclosure and then measuring, on the
periphery of the enclosure. the concentration of tracer gas. The lack of measurable tracer gas indicates that the
release of potentially hazardous gases or vapors within the enclosure at the tracer gas injection poirit{s) will not
result in their migration to the outside of the enclosure. Gas samples are taken by means of disposable syringes,
sample bags, or sample vials. Gas samples are analyzed by means of electron capture gas chromatography, infrared
spectrometry, or other equivalent means.
A2-3 Procedure
A2-3.l Tis! Dwrigrr
A2-3. I _ I Determine the volume of the enclosure.
A2-3.1.2 Measure the exhaust ventilation How rate from the enclosure.
A2-3.1.3 Calculate the air changes per minute of the enclosure by dividing the exhaust ventilation flow rate by the
enclosure: volume.
A2-3. I .4 Calculate the time at which the tracer gas concentration in the enclosure will achieve approximate
equilibrium. Concentration equilibrium oecul's when the tracer gas eoncentl'ation in the enclosure stops changing
significantly as a function of time for a constant tracer gas release rate. Divide 3 by the air changes Pei' minute to
establish this time. § A2-ti provides a derivation of the equilibrium time.
NOTE 2: This test method is intended to test the containment ability of the local exhaust ventilation system within an enclosure
when operated according to the equipment supplier's specifications. Thus, testing should be performed with the local exhaust
ventilation operating under its equipment supplier's recommended conditions.
A2-3. l .S Determine the release rate of the gas as described in § 7.
NOTE
In some cases, it may be practical to perform testing for a hypothetical release of the highest available flow of any gas
at the highest toxicity of any gas, even if those conditions pertain to different gases. If, however, the available flow of the more
toxic gases is substantially less than that of the Icss toxic gases, testing of several different model releases may be necessary to
determine the optimal exhaust ventilation flow.
33
semi
A2-3.2 Reagents and Ma f e ria fs
SEMI $6-0707 © SEMI 1993, 2007
A2-3.2-1 Use a tracer gas diluted in an inert gas, such as nitrogen DI' argon, as the tracer gas source, to minimize
measurement difficulties associated with small leaks of pure tracer gas from the supply cylinder and its associated
piping,
A2-3.2.2 The physical characteristics, including molecular weight, density and viscosity. of the tracer gas or tracer
gas mixture should be considered in detemrining its suitability to model the release of a particular' SOC.
NOTE 4: In pl'evicus documents. sulfur hesafluc-ride {SFR{} has been specified as the tracer gas to be used for this procedure. As
SF,, has been identified as a global warming gas, it is nn longer being specified- Any suitable gases nr gas mixtures may be used.
NOTE 5: Historically. SF, has been used in concentrations from l ppm to l% in nitrogen for such tests. Therefore the density of
the tracer gas mixture has been similar to that of air. There do not appear to have been measurement difficulties attributed to the
difference between the diffusivity of S l , and of the 5-OCs. although diffusivity is affected by molecular weight of the SF
molecules, not the density of the SF,',-"l'~l8 mixture.
A2-3.3 Sampling
A2-3.3.1 in selecting the location of samples collected outside the enclosure, consider' I I potential leak points, 2)
the direction of the release, 31 laminar flow characteristics in the area surrounding the enclosure and 4) that high air
velocities at the air sample point will result in dilution of the sample. Samples should be collected from all sides of
the enclosure, downstream in the prevailing room airflow, and in the operating personnel occupancy areasNOTE to: Results with room all' velocities greater than 0.13 m/s (25 linear feet per minute) may not be representative of the
conditions at the user's location and may produce results that lt: unit l'*1*t'~*1*1*-l'!* equipment that is in locations with lower
airflow rates around the equipment
A2-3.3-2 Co II e t l
at predetermined locations
f background levels above
I, and postpone the test until
When logistics pelnlit,
approximately I ppb
the concentration
background.
Islam:
*t area may also cause this
A2-3.3.3 Measure and record the air flow velocity (direction and speeds at each of the sampling, locations.
1
NOTE 7: If testing is pertitrmed with tracer gas background.
from any subsequently measured tracer gas concentration value.
concentration must be measured and subtracted
by
A2-3.3.4 Release tracer gas within the enclosure being Tested
means of an injection manifold, shown
schematically in Figure A2-I. The tracer gas injection manifold must be capable of measuring flow rates to an
accuracy of 15%. The tracer gas delivery line must be routed into the enclosure and positioned at a potential leak
point without violating the integrity of the enclosure.
rennin 14.1EcT»uu
i»oum;1:
.r
I up
luLL
sl-1uTorr
VALVE
CONFREBSIOH
UNION AMD GAS
Tl mf GOHTRU Elrufuts
ELECTFIOHE unss l=l.clw GOHTROLLERMUDATOH
menu vAur£
CHILI
ROUGE IE R w11H
* IE Run valve
now l'lllilIRclil[ R
Figure A2- l
Schematic Drawing of Injection Manifold
SEMI $6-0707 © SEMI 1993, 2007
34
sem
I
on
NOTE S: To minimize tracer gas contamination of the area sun'ounding an enclosure during a test, the end of the tracer gas
injection line should he capped. except when perfomiing an injection test.
A2-3.3.5 The time required for the enclosure to reach equilibrium should be considered when establishing the time
to begin sampling. The first sample after initiating tracer gas flow should be taken at the enclosure equilibrium time.
Additional samples should be collected at 1. 3 and 5 minutes thereafter. After taking the sample at 5 minutes. shut
off the tracer gas source. The final set of samples should he collected 1 minute after shutting oft' the tracer gas
source.
A2-3.3.6 Perfomi the test so that the location and direction of release, relative to any opening
of'
penetration in the
enclosure, effectively simulate an actual or foreseeable gas release, as described in § 7.2. More than one test should
he performed if it is not obvious which release location and direction represent the "reasonably foreseeable worst
case"
A2-3.3.6.1 A worst-case failure can be simulated by locating the tracer gas injection point at the potential leak
location closest to a penetration or opening within the enclosure with the direction of tracer gas injection pointed as
close as is reasonably foreseeable to directly at the opening or penetration. The flow velocity of the tracer gas
release should be no less than the How velocity of the l'ealistic worst-case leak. Details of release (flow rate, velocity,
direction, foreseen failure) should be provided in test report (see § A2-5.)
A2-3.3.7 After initiation of tracer gas injection, collect grab air samples from the area surrounding the enclosure at
predetermined times and locations. These samples should be analyzed immediately after collection. If this is not
possible, they should be sealed. Label the samples as to time and location. Samples may be taken with al containel's
that are non-absolbent, inelt, and that have low pemieability [such as polyvinyl fluoride film or polyester film
sample bags or polyethylene, polypropylene, nylon, or glass bottles) or b) disposable syringes. Disposable syringes
can he used to irtiect samples into the gas chromatograph directly when using gas chromatography to analyze
samples.
A2-3.3.8 Record al the actual (measured) tracer gas release rate, be the actual tracer gas concentration in the tracer
gas being used. and cl the actual release time during a test.
A2-3.3.9 Collect air samples as described in § A2-3.3.6, and analyze them for the presence or absence of tracer gas
using a gas chromatograph, infrared spectrometry, or other suitable method with sufficient sensitivity. The
measurement of a tracer gas concentration above background in the area sulrounding an enclosure indicates
incomplete containment of contaminants within the enclosure.
A2-3.3.10 Analyze samples according to recognized test methods for the analytical equipment to be used. Samples
may he analyzed immediately after a test, or they may he stored for litture analis i S. Experience has shown no
degradation of concentration of SF,, in polypropylene syringes when stored tor several months as long as the needle
or syringe is plugged.
A2-4 Calculations and Interpretation of Results
A2-4,I The maximum concentration of tracer gas measured in a sample collected outside the enclosure is used to
calculate the Equivalent Release Concentration (ERC) by the following formula:
ERC
{Process Gas Concentration )x (Measured Tracer Gas Cnneentmtion }
{lrljected Tracer Gas Concentration]
(A2-I)
NOTE 9: Related Information 6 presents the derivation of this formula.
A2-4.2 Compare the Equivalent Release Concentration to the relevant control limits. If the ERC is above the
prescribed limits, the enclosure is not considered to he acceptable for the SOC and conditions tested; if the ERC is
less than or equal to the prescribed limit, the enclosure is considered acceptable for the SOC and conditions tested.
SEMI $2 recommends appropriate control limits for an enclosure.
A2-4.3 Suitability of test results to specific installations should be assessed by the insfalling facility's occupational
safety and health professional. Where air velocity outside the enclosure is greater than the air velocity during the test,
the concentrations outside the enclosure are expected to be lower. Where air velocity outside the enclosure is lower
than the air velocity during the test, the concentrations outside the enclosure are expected to be higher.
35
SEMI S6-D707 © SEMI 1993, 2007
semi
A2-5 Reporting Results
A2-5.l Describe tracer gas injection points within individual enclosures to detail location and proximity to openings,
penetrations. exhaust ventilation grillwork. accessways, and other potential leakage sites, such that worst-case leak
conditions have been simulated. Include the tracer gas velocity needed to simulate the realistic worst-case leak
velocity [velocity of release).
A2-5.2 Describe the sampling locations and the air flow velocity (direction and speed) at each of the sampling
locations.
A2-6 Equilibrium Time for Tracer Gas Injection
A2-t1.I If a tracer gas is injected at a constant rate into an enclosure that possesses a constant exhaust ventilation
rate, the concentl'ation as a f i c t i o n of time is given as:
CH) = (FAQ) [I
(A2-2}
ex;J {-{ QM! % ]
where :
Elapsed time since initiating injection
II
v
Exhaust ventilation rate of enclosure
II
T
Injection rate of tracer gas
II
Q
Concentration within the enclosure
II
F
II
Car)
"v'olLlme of iheund
NOTE ID: The term
(in
Curl to he constant,
L telm is
the exponential teml r*
The time at which this I
l'qv"vJf=3
equal to
E-I
1A2-33
from which it follows that the equilibrium time is given as:
{AZ-4)
1A2-5)
SEMI $6-0707 © SEMI 1993, 2007
36
semi
APPENDIX 3
TEST METHOD FOR AEROSOL VISUALIZATION
NOTICE: The material in this appendix is an official part of SEMI $6 and was approved by 6111 letter ballot
procedures on April 25, 2007 by the global Environmental. Health & Safety Committee.
NOTE I: Aerosol visualization has been more commonly called "vapor visualization". What is ab:-:c:rv4:d visually, howcvcl; is an
aerosol. An aerosol is a suspension ofsolicl or liquid particles in a gas (in this ease ai1'}.
A3-1 Description of Method
A3-l.l Aerosol visualization is performed by replacing some of the air with a visible aerosol, lt may also be
necessary to replace one
of'
more walls of the enclosure with a substitutes made of a transparent material.
A3-I .1. I The visible aerosol may be produced by a chemical smoke generator, although such devices are not
popular in the semiconductor industry because of the residual contamination of the test ohiecl surfaces.
A3-1.1.2 More commonly. an aerosol of" water droplets. produced by cooling humid air {c.g., by using dry ice or
liquid nitrogens or by a mechanical device (e.g., de-ionized water mist generatorlA3- I .2 Aerosol visualization is a qualitative means of assessing the flow behavior of exhaust ventilation,
A3-2 Applications
A3-2.l The aerosol can be used to fill an enclosure and the ability of the exhaust ventilation to remove the aerosol
can be observed as an indicator of the ability of the exhaust ventilation to remove gases.
A3-2.2 The aerosol can be released within an enclosure to enable one to see how the exhaust ventilation dilutes or
captures similar releases.
A3-1.3 The aerosol can be released into the air entering an enclosure to replace the air removed by exhaust
ventilation to enable one to see the flow path.
A3-2.4 Aerosol visualization can provide rapid. qualitative assessment ofdesig,n features, including:
.
.
air inlet and outlet locations
battles
9
How around components within enclosures
*
identification of areas in which gases or vapors may accumulate.
A3-3 Reporting
A3-3.l The report should include the exhaust ventilation conditions that were tested, the means by which the
aerosol was generated. and a qualitative description of the findings.
A3-3 .2 The repoit may include still or motion images of the testing.
37
SEMI 56-0707 © SEMI 1993, 2007
semi
APPENDIX 4
TEST METHOD FOR AIR PATTERN ASSESSMENT FOR FLAMMABLE
GAS AND VAPOR SOURCES
NOTICE: The material in this appendix is an official part of SEMI $6 and was approved by full letter ballot
proccdurtxs an April 25. 2007 by the global Environmental. Health & Safety Committee.
A4-1 Purpose
A4- l . l This test method is intended to test the exhaust ventilation system's ability to provide dilution air within an
enclosure sufficient lo keep the concentration of a leaking gas (or vapor generated from a liquid spill or leak) less
than 25% of the LFL for that gas near potential sources of ignition.
A4- I .2 Test data obtained by means of this test method apply only to the local exhaust ventilation conditions that
existed within the enclosure during the testing- Extlapolation of the test data to other exhaust ventilation operating
conditions is not usually valid.
NOTE I: An acceptable enclosure does not imply a safe condition tor routine equipment operation with a leak or a tuhiltgifitting
failure. An acceptable enclosure and exhaust ventilation system is one that will provide enough dilution in an emergency, nonroutine situation. The fact that an enclosure is acceptable does not imply that the equipment should remain in operation when a
flammable gas leak has been detected.
A4-2 Summary of Method
l
At a given 4.ulilauullst
inject tracer goto
4.
Compare the nnnupl
2.35.
If the samplendli
Ilrn.nhnlll»uh:rlilI:1iln
Collect and I
or
,
make changes to the
enclosure or flow characteristics and repeat the tes
A4-3 Procedure
A4-3.l Test Design
A4-3. I .I Set the exhaust ventilation flow rate to the equipment supplier-specified flow rate.
A4-3.1.2 Charaeterize the How within the enclosure. This may be performed by using an aerosol visualization
method (see Appendix 3) or by direct measurement of air velocities within the enclosure. using an instrument such
as a hot wire anemometer. Characterization should be performed with covers arid doors intact and iii place as they
would be during nomtal operation of the equipment. The covers of' doors may be simulated using plastic ot' some
other material to provide typical sealing. but also to allow holes to he drilled for the insertion of the measurement
instrument with minimal disturbance to the airflow.
A4-3.1.3 During characterization, How velocities near potential ignition sources and potential leak sources should
be noted in order to determine the worst -case release locations and sampling locations.
NOTE 2: Actual How velocities required to provide sufficient dilution will depend on the LFL of the gas in question, the release
rate of the gas during a worst-ease leak, and the characteristics of the enclosure itself {e.g., size, shape, location of make-up air
pcnetiations, location of components within the enclosure). The air velocities needed at any given point inside the enclosure
cannot be determined by calculation.
A4-3. 1.4 Determine the release rate of the gas as described in § '7.
A4-3.1.5 In some cases, it may be practical to perform testing for a hypothetical release of the highest available
flow of' any gas at the lowest LFL, even if those conditions pertain to different gases. If, however, the available flow
of the gas with the lowest LFL is substantially less than that of the gases with higher LFLs, testing of several
different model releases may be necessary to determine the governing fault scenario.
A4-3.1.6 Calculate the time at which the tracer gas concentration in the enclosure will achieve approximate
equilibrium.. as described in Appendix 2.
SEMI $6-0707 @ SEMI 1993, 2007
38
semi
A4-F!i.l.7 Determine where tracer gas should be released. To estimate the worst-case location, consider potential
leak or spill locations, locations flower air velocity (resulting in less dilution air available). and the direction of the
release. l o n e single worst-case location cannot be determined. more than one test may be required.
A4-3. I .S Determine where samples should be collected. Samples should be collected at all potential ignition
sources within the enclosure. If potential ignition sources outside the enclosure may be affected by a fault within the
enclosure. samples should be collected there as well.
1~' also be collected at the expected I ocation of a tlammabI e gas detector in order to detemline the expected
Samples may
concentration of a leaking process gas within in the exhaust ventilation stream. This intimation may be useful when determining
II the required set point for flammable gas detectors in the exhaust ventilation stream, and 2`} whether abatement is required for
the exhaust ventilation stream.
NOTE
A4-3.2 Testing
A4-3.2.1 Testing should be performed using the aemal gas in question where practical and safe to do so. Otherwise,
a tracer gas should be used (see Appendix 2 for a discussion of tracer gas, sample collection devices, and analysis.
A4-3.2.2 Collect background (baseline) samples tor the gas in use from the area surrounding the enclosure at
predetemiined locations. When logistics pemiit, anal y e the background samples before pelforming the test. If
background levels above 1% of the LFL for the gas in question (actual gas if using actual chemistry, of' the
r
equivalent concentration of tracer gas if using a tracer gas). evaluate the integrity of' the chemical delivery system
and other sources chemical iii the immediate test area- Eliminate any background soul'ces that exceed 1% of the LFL
iii concentration.
A4-3.2.3 If testing is perfomied with a gas background, the background concentration must be measured and
subtracted from any subsequently measured concentration value.
A4-3.2.4 Flow the tiaccr or actual gas for the time to reach equilibrium within the enclosure. Once the equilibrium
time has been reached, collect a single sample in each location as described in § A4-3.1. After all samples are
collected, stop the flow of gas.
A4-3.2.5 Analyze samples according to recognized test methods for the analytical equipment to be used.
A4-4 Calculations and Interpretation of Results
A4-4.I If testing was performed with the SOC, sample results should he compared to 25% of the LFL for the gas in
question- If all sample results are below 25% of the LFL, the exhaust ventilation system is satisfactory at the exhaust
ventilation flow rate specified.
A4-4.2 If testing was performed using a tracer gas. the samples should be analyzed In determine their tracer gas
concentration. The percentage concentration of tiaecr gas is then calculated and compared to the LFL for the process
gas.
A4-4 .2. I The eoncentmtion is calculated as follows:
Percentage Cone.
(Measured tracer gas sample cone. - Background tracer gas conc-l x 100'&
(A4-I
u
(Tracer Gas Injection Gas Coneenhatienl
A4-4.2.2 If the percentage concentration is less than 25% of the LFL of the gas in question at each sample location,
the exhaust ventilation system is satisfactory at the exhaust ventilation flow rate specified.
A4-4.3 If the results of either the tracer gas ot' the actual chemistry testing indicate that samples concentrations near
potential ignition sources ate larger than 25% of the LFL, then the test has been failed.
A4-4.3.1 In order to the pass the test, engineering changes (such as changes to the path of the dilution airflow or
restricting the available Flow of flammable gas). may be required or more exhaust ventilation flow may be needed.
After making engineering changes or increasing the exhaust ventilation flow, velocities in the areas that had failing
sample results can he measul'ed to v e i l that the velocity has increased compared to the initial measurements taken.
Iterative testing should continue, with engineering changes of' exhaust ventilation flowlate increases, until all sample
locations results are below 25% of the LFL.
I9
SEMI $6-0707 © SEMI 1993, 2007
semi
A4-5 Reporting Results
A4-5.1 Present all results as required in § 8
A4-5.2 Describe in detail sampling points, and 1Tacer gas injection points of' fault scenarios as required.
do
rw
SEMI $6-0707 @ SEMI 1993, 2007
40
semi
APPENDIX 5
TEST METHOD FOR FACE VELOCITY MEASUREMENT
NOTICE: The matelial in this appendix is an official part of SEMI $6 and was approved by full letter ballot
proccnlures on April 25, 2007 by the global Envirolimental, Health 8: Safely Committee.
A5-1 Method
A5-l.l
The preferred method is measurement of average face velocity and static pressure.
A5-l.1.l Face velocity measurements are taken with an anemometer. Multiple measurements are taken in a grid, at
least II) per square meter ( I per square foot) o f open area, in the plane opening of the hood [see Figure A5-I I. This
allows representative, evenly spaced measurements lo be taken.
»=:> Circles represent equidistant sampling
points along the open face of the hood
Fignne A5-1
A5-1.2 ASHRAE Standard I 10, or equivalent (use appropriate sections), for tracer gas testing of lab hoods may be
used for AEV verification provided that an accurate emission tale can be defined. (ASHRAE I 10 lists 3 tests: "as
manufactured," "as used," and "as installed." The "as manufactured" test is the test that is used most ii'equently.l
A5-2 Reporting
A5-2. l The report should include:
.. the exhaust ventilation conditions that were tested
•
a diagram showing the locations of velocity measurements
.
the velocity measured at each location
l
the locationlsi and result's) of the static pressure measurement{s}
41
SEMI S6-D707 © SEMI 1993, 2007
semi
APPENDIX 6
TEST METHODS FOR FLOW AND PRESSURE
NOTICE: The matelial in this appendix is an oflieial part of SEMI St'l and was approved by lilll letter ballot
procetlurcs on April 25. 2007 by the global Environmental, Health & Safety Committee.
A6-1 Exhaust ventilation flow and pressure measurement
A6- 1. I The static pressure and flow readings should be taken downstream of the vena contracts, in a location where
the normal static pressure and velocity pressure relationship has become established. Taking the reading within the
vena connacta will provide inaccurate results {e.g.. high velocity or velocity pressure, low static pressure).
A6- I .2 Readings should be taken before any fittings or obsuuetions (c.g.. dampers., elbows, or sprinkler heads) that
would alter the velocity or velocity pressure.
A6-1,3 A low range differential pressure gauge (0-60 Pa or 0.0-40.25 inches of water) is preferable tor velocities
over 3 mf (600 Fpm). A hot wire anemometer is acceptable for velocities less than IO mis [2000 fpnl} and preferred
for velocities less than 3 mfs (600 fpm). Ensure that the equipment is capable of measuring within the required large.
A6- I .4 Turbulence in the duet at the point of measurement should be minimized. The measurement point should be
in 8 straight section of duet. It should be downstream in the connecting duct past the vena conttaeta iron the last
tlansition made in the equipment. Normal recommended practice is 7.5 duct diameters Rom any point of connection
or fitting. See "HVAC Systems Testing, Adjusting. -11-mufuu-=»'~=s :J
..
dlltlihution, and
NOTE l: The type of dilItnfblnl:ujld'tI5l 1Hulunll1]flnlluilllnfI
duration of the lurbulcncc,
for example:
a partially closed d
an elbow moves the
turhulencc will pm
111W
A6-2 Duct Traverse Method
A6-2.l Because the airflow in the: cross-section of a duct
measuring velocity of' velocity pressure (VP) at points in
|
it is necessary to obtain an average by
dual areas in the one~~s-section. The usual
method is to make h o traverses across the diameter of the
_..
les to each other. Readings are taken at
the center of annular rings of equal area. Whenever possible. the traverse should be made at least 7.5 duct diameters
downstream and 3 diameters upstream from obstructions or directional changes such as an elbow. hood. or branch
entry. Where measurements are made closet' to disturbances, the results should he considered suhiect to some doubt
and checked against a second location. If agreement within 10% of the two traverses is obtained, reasonable
accuracy can be assumed and the average of the two readings used. Where the variation exceeds l 0%, a third
location should he selected and the two airflows in the best agreement averaged and used. The use of a single
centerline reading for obtaining average velocity is a very coarse approximation and is not recommended. If a
traverse cannot be done, then the centerline duct velocity should be multiplied by 0.9 for a coarse estimate of actual
avelage duct velocity. Center line duct velocity should not be used less than 5 duct diameters from an elbow,
junction, hood opening, or other source of turbulence.
A6-2.2 For ducts 150 mm (6 inches) and smaller, at least (1 traverse points should be used. For round ducts larger
than 150 mm (6 inches diameter, at least 10 traverse points should be used.
A6-2.3 For rectangular duets, the procedure is to divide the cross-section into a number of equal rectangular areas
and measure the velocity pressure at the center of each. The number of readings should not be less than 16. Enough
readings should be made so the greatest distance between measurement points is less than 150 mm (6 inches).
A6-2.3.1 The following data should he recorded and reported:
the area of the duct at the traverse location
velocity or velocity pressure at each point in the traverse andfcr average velocity and number of points
measured
I.
temperature of the air stream at the time and location of the traverse
SEMI $6-0707 © SEMI 1993, 2007
42
semi
A6-2.3.2 If the velocity is not measured directly at each point, the velocity pressure readings obtained are converted
to velocities, and the velocities [not the velocity pressures) are averaged. Useful equation: V = 4.043 ivp,»'di0.5, where
v=
velocity in Ws, VP = velocity pressure in mm H8O, and d = density correction factor (unitless), Some
monitoring instl1.1ments conduct this averaging internal to the instrumentA6-2.3.3 Flow measurement
temperature, i.e., 21°C [7{]oF).
taken at other than standard air temperatures should be corrected to standard
43
SEMI $6-0707 © SEMI 1993, 2007
semi
RELATED INFORMATION 1
EXAMPLE EXHAUST VENTILATION PARAMETERS
NOTICE: This related intonation is not all official part of SEMI $6 and was derived from the work of the global
Environmental, Health & Safety Commillee. This related information was approved for publication by full letter
ballot on April 25. 2007.
R1-1 Example Design and Test Parameters for Ventilated Enclosures
R l - I .1 Table R l - 1 provides example design and test parameters for exhaust ventilation design for semiconductor
manufacturing equipment.
NOTE I: The values in the table are not design or performance criteria. The values have been found to be appropriate in some
equipment, but one should not assume that they are appropriate for other equipment.
Rl-1.2 The exhaust ventilation velocities, volume flow rates and pressures listed are derived from a mixture of
suecesslitl empirical testing and regulatory requirements; however, design based solely on these parameters does not
ensul'e compliance with SEMI So, or with requirements imposed by the local .jurisdiction in which the equipment is
used.
Table H1-1 Example Design and Test Parameters for Ventilated Enclosures
Enclosure
Time
Example Design and Test Exiwmr l»-era1'fh:n'ora Pururraefers
Wet Station
0.28 to (LSU rMs (55 to 100 fpm} capture velocity for non- Appendix 2 of SEMI $2
hcatod
ACGIH Industrial Ventilation Manual
capture velocity for
0.36 [0 0.76 m-'1». (Jim
heated processes
120 to 125% of the
the lop of the deck
Gas Cylinder Cabinets
References
l
_ I
Q
volume flow rate across
LD to 1.81 mf 1200 to 250 fpm} face velocity
Appendix 2 ofl5EMI $2
ACGIH Industrial Ventilation Manual
Enclosure
4 to 5 air changes per minute
- I RE to -366 Pa 1-0,05 to -Ill "w,g.I static pressure
Appendix 2 ofSF.Ml $2
ACGIH Indu.-:trial Ventilatioii Manual
Diffusion Furnace
Scavenger
0.50 to 0.76 mf ( I D ) to 150 fpm face velocity
NOTE: Do not use hot wire anemometer.
ACGIH Industrial Ventilation Manual
Chemical Dispensing
Cabinets
- I33 to -366 Pa 1-0.05 in -0.1 "w.g.1 static pressure
Appendix 2 oflSEMl $2
2 lu 3 air changes per minute
ACGIH Industrial Ventilation Manual
Parts-Cleaning Hoods
0,40 to 0,64 mJ"s (30 to 125 fpm} face velocity
Appendix 2 Of SEl"v'II $2
ASHRAE Standard I In
Equipment Gas Panel
Appendix 2 of SEMI $2
ACGIH Industrial Ventilation Manual
Glove Boxes
No consensus for a reference at the time of publication of
this guideline.
Appendix 2 ofSEMl $2
ACGIH Industrial Ventilation Manual
Drying! Bake! To!
Chamber Ovens
- I83 to -3645 Pa 1-0.05 to -0.1 "w.g-} static pressure
Appendix 2 of SEMI $2
ACGIH Industrial Ventilation Manual
Ovens
lace velocity of0.5 to 0-76 m s (HH) to 150 Ism)
Spin-Coater (cup only)
See SEMI $2 §§ 23.5.1-3
Appendix 2 of SEMI $2
ACGIH Industrial Ventilation Manual
Closed wet processing
equipment PER:
-366 to -3600 Pa 1-0. 1" to - l .0 "w.8.l static pressure
ACGIH Industrial ventilation Manual
Appendix 2 ofSEMl $2
4 to 5 air changes per minute.
-399 to -3600 Pa 1-0. I" to -I .0 "w.g.l static pressure,
face velocity 0- I N to 0.46 m.»'s (35-90 fpm`},
3 lo 5 air exchanges p-cr minute
Closed wet processing
equipment SEV*
I
AEV
ACGIH Industrial ventilation Manual
Appendix 2 ofSEM[ $2
I
See SEMI $2 §§ 23.5.1 3
SEMI $6-0707 @ SEMI 1993, 2007
44
semi
RELATED INFORMATION 2
RELATIONSHIP TO FACILITY EXHAUST VENTILATION SYSTEMS
NOTICE: This related information is not an official part otlSEMl $6 and was derived from the wol1< of the global
Environmental. Health & Safely Committee. This related inll<J1-lmalicm was approved for publication by Tull letter
ballot on April 25. 2007.
R2-1 Attributes of Typical Semiconductor Facility Exhaust Ventilation Systems
R2-l.l A typical semiconductor facility's exhaust ventilation system has three measurable working elements: ( I )
flow velocity, (2) flow volume, and (3) pressure.
1
R2- I .l. I Flow volume is related to the flow velocity by the ctuation Q = VA. In this equation, Q = volumetric How
rate, V = average velocity, and A = duct cross sectional area (nt
nt or
orI).
R2-I .2 There are three duet pressure measurements possible: ( I I static pressure, 121 velocity pressure, and 131 total
pressure.
R2-I.II in exhaust ventilation distribution systems with central fans and abatement equipment (typical of
semiconductor facilities). exhaust ventilation duct pressure (static) upstream of the fan is less than the ambient
pressure outside of the duct.
R2-l,2.2 While veI city pressure (VP) and total pressure (TP) provide a more reliable measure of flow than static
pressure, VP and TP are normally not specified for semiconductor facilities' exhaust ventilation system s, therefore,
they will not be discussed in these guidelines. If more information is desired on VP or TP. it can be found in
.
Industrial Ventilation in
R2-L3 Facility exhaust ventilation systems are designed to balance efficiency, flexibility and installation costs. In
addition they are not to induce vibration into the building supel"stmcmre via vibration or noise.
R2-I .4 Velocity
R2-I .4.1 The desired velocity in the facility exhaust ventilation duct is no higher than is necessary for transport of
the contaminant. Industrial Ventilation calls for S. 1-l0.2ml's {l000-2000 l`pm} velocity for vapors. gases. and smoke.
This is all the velocity that is needed to transport the emissions typical to semiconductor processes. Higher velocities
expend energy needlessly and induce vibration and noise.
R2-I .4.2 One usel' strives to limit velocity in sub-mains to 10 mis (2000 fpm) in 40 cm (16 inch) diameter duct and
12 mfs (2400 fpm] in 30 cm (IZ inch) diameter duct. They have exceeded these velocities and have not experienced
deleterious effects. The recommendations listed below for connecting ductwork allow for slightly higher numbers.
R2- I .5 Static Pressure
R2-l.5.l Most facilities will have -5500 Pa {-l.5 "w.g.} available at the equipment. Some facilities guarantee
-7300 Pa (.-2 "w.g.). Others, particularly those that require more equipment exhaust ventilation that was originally
planned. may provide as little as -3660 Pa 1-L1l "w.g.1. Equipment suppliers are encouraged to engineer designs that
do not require excessive negative static pressure.
R2-I.S.2 The target static pressure range at the point of connection to equipment is -I 80 to -5500 Pa {-0.05 inches
to -1.5 "w.g.). This permits flexibility of equipment placement with minimal need tel' pl'essure boosting devices,
such as booster fans.
R2-1.5.3 Booster fans are sometimes used to increase flow or static pressure in the equipment. If the system is
improperly balanced. air in the duct work down stream of the fan can be above ambient pressure. causing fugitive
emissions. This situation should be prevented by monitoring the pressure downstream of the fan with an indicating
pressure sensing device. The output of this device should be interlocked to cut power to the fun in the event that the
static pressure reaches - I D Pa 1-0.05 "w.g.). The static pressure monitoring point should be located on the discharge
side of the booster tan, between the fan and any exhaust ventilation balancing devices such as blast gates of' dampers.
16 ACGIH. .fndusrrfui Ventifnrfon, A Hanna! of Rc='c'om1n¢°r1d-f'd Pm<'tic'=f'. 1330 Kemper Mcadnw I`Jrivl:, Cincinnalti. OH 45240- 1634. USA.
htlpz.-':"www.acg.ih.n1',g. Library ofifongress Catalog Card Number: 62-12'*}2'*l'.
45
SEMI S6-D707 © SEMI 1993, 2007
semi
R2-2 Connection to Facility Exhaust Ventilation Systems
R2-2.1 The duct size of the equipment connection should fall in the low How velocity range of the duct friction
table. (See HVAC S.wrrwris Duct Design.) Low flow velocity ducts will promote flexibility and ease of interface to
exhaust ventilation systems serving more than one piece of equipment, When particles are to be captured and
removed, design the system for the minirnuni flow velocity that will ensure capture.
NOTE I: Exhaust ventilation system designers should always keep in mind the difficulty that can he experienced in flow
velocity measurements in unduly large ducts, Equipment connections should he sized for accurate flow measurements.
R2-2.2 To maintain velocities in the optimal range, the following table may he used for guidance:
Table R2-1 Typical Connection Duct Sizes
Dum' Diuanerer
(inches)
Area (sq.
) Vc'lfn:'it}' (fpm)
Pressure
Pa ( "n'.g.)
Vih1c'iJ'}"
-
CFM
2
0.02 I R
2294
1190 (03251
50
4
0.0373
2290
1190 (0325)
200
15
0. I 963
2583
1519 10.4151
500
II
0.349 I
2573
15 l *J 10.4 I 5)
9{}'[l
R2-2.3 The users' ulchlulrlwmdlnlinudilhihuinn lystnmltyplinalljrhnldjbllannu setting i2fI% of the set pointtsl
requiring tighter stability control,
over time. Equipnmuullriu
hlghltrluir uunhalult
is a special case aOld illnrllldhc
R2-2.4 The suppl
tolerance of -0%
£dld1hetimnelrxl'
should include a
|
'vlniiilatiun distribution
system balance.)
R2-2.5 Equipmettli mmpggrliur nhnuld npudzfy euchaud wruntildi
-==d==q1n»=merits, See
the appendices and
§ 9.
R2-2.6 End user should set limits so that expected variations in exhaust ventilation flow and pressure do not cause
l'll.1lsllllcc tripping, of exhaust ventilation alarms on equipment interlocks.
R2-3 Other Facility Considerations
R2-3.1 Some user cleanrooms are designed using the "hay-and-chase" concept. The bay is served with l 00%
ceiling-supplied. HEPS-filtered air. Vertical airflow below the ceiling is typically 0.5 mis H00 FPM} across the
entire hay. The chase section is the return air plenum for the hay air supply system. The typical pressure differential
across the bay wall is 36.6 to 1(l9.8 Pa ((l.t}1 to 0.03 "w.g.}, with the lower pressul'e on the chase side.
R2-3.2 Bulkhead or through-the-wall mounted equipment should tolerate this pressure dit`t`erentiaIR2-3.3 Cabinet or enclosure exhaust ventilation applications should be designed so that back streaming into the
clean bay or chase is prevented.
R2-3.4 The equipment should have the capability to shut down chemical delivery in response to an external signal.
R2-4 Equipment Considerations
R2-4,1 The design of the equipment exhaust ventilation connection should allow fOr long radius connecting elbows
at the point of connection. This will reduce friction losses. Additionally, the equipment supplier should avoid
configurations that would require an angle of entrance into the user's branch ducts of greater than 30 degrees where
possible.
R2-4,2 Duct connection configuration should be such that liquid spills or releases within the equipment enclosures
will not enter the facility's exhaust ventilation system.
SEMI $6-0707 © SEMI 1993, 2007
46
semi
R2-4.3 Flow through the equipment enclosure, and the duct at the point of connection, can be specified in velocity
or volume. Normally, the balancing engineer will measure How velocity and convert velocity to flow volume using
the equation Q = VA .
R2-4.4 The equipment supplier should establish, through testing, the flow velocity, volumetric flow rate, static
pressure, and duct attachment point diameter required for efficient operation of` its equipment's exhaust ventilation
system. The user and the supplier should Ag,ree, before the purchase of the equipment, on the safety control devices
to be used. Any safety control device requiring flows or pressures outside these ranges is a special case and should
be resolved at the time of purchase.
47
sem
SEMI S6-D707 © SEMI 1993, 2007
I
on
RELATED INFORMATION 3
GENERAL DESIGN RECOMMENDATIONS
NOTICE: This related information is not an official part of SEMI $6 and was derived from the walk of the global
Environmental, Health & Safely Committee. This related inllolTnation was approved for publication by full letter
ballot on April 25. 2007.
R3-1 Factors that Affect Equipment Exhaust Ventilation Requirements
R3-l .1 SEMI $2 establishes specific criteria tier ventilated enclosures of equipment that use substances of CDIICEITL
Access to enclosures containing substances of concern may necessitate special design. If there is a potential for
exposure of personnel to substances of" concern when an accessway is open, an average face velocity (measured at
the accesswayl sufficient to capture the substances of concern should be maintained in the accessway opening.
(SEMI $2 also has recommendations for exhaust ventilation monito1ing and alarms. SEMI $2 should he fully
understood before designing exhaust ventilation systems for substances of concem.l
R3- I .2 Face velocity should not be relied upon to control emissions from a pressurized lining
R3-L3 Propeities of chemicals (density, vapor pressure, boiling point, tlammahtltty, evaporation rate. etc.}, the
state of the chemicals within the ventilated enclosure (solid, liquid, or gas), and conditions such as tempeiature and
concentration will determine the final design and exhaust ventilation specifications of the equipment enclosure.
Equipment suppliers should use available reference hooks and Material Safety Data Sheets (MSDS) to obtain
in florniation on chemical properties. The equip re rrtiprnnnuln unnditlnul
by-products. Dilullllll
nuiadngufreactitfe dlenmri
dnnnmm
Hnnmlu'
eoirosivc solidsfliqmill
vqllillll
determine the state of the chemical and
anticipated hazards (e.g., fuefexplosion,
al.
performance
{c.g., deposition of solids)
R3-2 Enclosur.l
R3-2.1 Exhaust
reducing the overall exhaust ventilation and
et
==Ir5tr=»1
"
ated some very effective means of
pl'otectioll for persounf: I and
Po viding
equipment. This Related Information describes some of the best known of the praetiees for designing enclosures for
substances of eoneem
R3-2.2 Enclosure designs for substances of concern may incolporate the following methods cafimprovement:
.
reduced ripening size (see Figures R8-I through R3-4'}
reduced interior exposed opening (see Figure R3-Sl
removal of components without leak potential from enclosures
installation of automatic dampers
design for easy hazardous energy control that prevents the need for working in (chemical) energized locations
modularizing wet bath systems
optimizing airflow within the enclosure [see Figures R3-6 through R3-l II
baffles
tel' air inlets to prevent high velocity gas releases from being directed at ail' inlets
sealing unnecessary openings {e.g., seams }
SEMI $6-0707 @ SEMI 1993, 2007
48
semi
-l
1m (3f1)
r
1
01
C'J
Hinge
Handle
U
C)
1m (3f1)
Figure R3- I
Single Du-ur
u
Figure R3-2
Double Doors
Small
Work
Door
1
SnwW
Work
Door
4
1
|'
.
L-'
o
...
1
w
Figure R3-3
Figure R3-4
Small Work Door
Secondary Work Do-nr
Assembly
I Door
I
I
4'
Interior
,1"
Barrier
U
ActuaI
Main
Door
II
/'
Working
Area
Behind
Door
Figure R3-5
Interior Barrier
SEMI $6-0707 © SEMI 1993, 2007
49
semi
!
!
!
!
!
u - l l _ l l - l l - l l - l l - l - I
I
I
i
i
I
i
I
.i
I
!
I
i
I
I
.I
I
I
I
I
I
I
I
.I
I
I
I
I
II
r
"""""""'1
'm
I
|
I I - l l - l l - I - I I - I
i I
i
I
I I
I
!
I II
I
I L
I
I
I
I
I
I
r
I
I
I
L I'
I
I
I
I
I
'I
I
I
I
I iI
I
I
I
I
"I
I
I
H
I
I
I
"-.v
I
I
II II
I
I
.3
E
L
I""!
!
E
I I
!
I !'
l *'|-!
J1
.
. . | .
.
I I
_
I
I
I I Ah;I I
I n-n I I
I I A-
J
"
I
I
I
I I L -I I
-
III - II
-
1*
I
I r'
I I
I- I
II
I ma I I - I I
J""~».
.1.1
rI
I
I
I
I
I
i
I
I
I
I
I
I
II...
...r
!
I
I
I
I
i
I
I
I
i
I
g
i
!
r"
I
I
._.I._._.,
__
l_
I
i
I
I
I
.
_
r".'".
--
I
I
i
I
, J
!
!
I
I
I
I
I
<'
I
111111111111111111111111111II
I
I
I
|-
Door Handle
!1
I
I
:
I
I
\
J-1 .
| H-II r 1 1 5
l
|
E I
!s
I
r
i
|
I
.
.
I I
-
I II
t
I
I1
.r
r
I
anl1|-ill»_l11-|ll|-_lll¢-lll»_¢llL-
Figure R3-6
Figure R3-7
Multiple Intermediate Shield/Accessways to
Main Door Provides Full Access when All
Reduce Overall Exhaust ventilation Requirement
Intermediate Panels are Removed
l
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
o
O
O
O
O
O
O
,/
it'
Figure R3-9
Figure R3-8
Main Chemical Stick Box (Gas or Liquid) Behind
Perforated Component-Mounting Panel
Perforation
SEMI $6-0707 © SEMI 1993, 2007
50
semi
-{
Additional
Chemical
Distribution
"sticks" in
this area
4
I
I
Figure R3-10
Mounted Components
E
s
s
r
I
. .... . .
..
t o o - . :
I
1
-
I
L._.........
'l
I
I
Q
.
|
L
............
<1 i:>
Exhaust
Connection
*
L
r.na-1~""-'-I1
!
I
Main Door
!'
*""""'"g""""""!
Q
I
Main Chemical
"Stick" Box
Interior
Access Shield
Panels
Perforated"
Chemical Piping
Component "Stick"
Mounting Panel
Figure R3-l I
Chemical "Stick" Bm: Side View
51
SEMI S6-D707 © SEMI 1993, 2007
semi
R3-2.3 Exhaust ventilation enclosures, capture zones, and entry points in the equipment should isolate the area to be
1-'enlilated from adjacent areas. Internal ducts, partitions, and guide plates in the equipment should be leak tight to
prevent the release of contamination from the exhaust ventilation stream.
R3-2.4 To capture. move, or dilute contaminants effectively within the equipment's exhaust ventilation enclosure,
there must be a continuous supply of make-up air. The enclosure should he designed such that the make-up air is
drawn from a selected urea through designed openings in the enclosure walls. Care should be taken to ensure the
make-up air does not contain, or potentially contain, vapors or fumes that could be incompatible with the exhaust
ventilation enclosures material of construction, components, or target materials being removed.
R3-2.5 Minimize the volume of the enclosures where possible to reduce the load on the exhaust ventilation system
and on its companion make-up air system.
R3-2.6 Enclosures supplied with, or as part of, equipment should be designed so that exhaust ventilation properly
sweeps all potential emission release points. Areas of low aerodynamic flow inside the enclosure should he
minimized and should not be allowed for highly hazardous materials.
R3-2.7 Components that have no potential for release should he located outside the enclosure, when possible.
Additionally, the handles for any valves located inside the ventilated enclosure should be positioned outside of the
enclosure to reduce the need to open the enclosure.
R3-2,8 Rrduvefd A(.'n'5s Opening Sig#
R3-2.8.1 The exhaust ventilation volumetric flow rate required to hold rqinor leaks within the enclosure becomes
larger as the opening size increases
R3-2.3.2 Sometimes he apunilsdmairuuadstnhu lug:
but often, the person 1:
R3-2.8.3 When the 1
reduce the size
(1
Mann 'ID have access to the components,
are:
fichu
provide multiple doors of smaller size (see Figure R3-81
place the door over the few components that will require regular maintenance or aeeess (see Figure R3-9)
place a second, single-hand size opening in the door that allows the individual to open the smaller aecessway to
perform quick adjustments {.e.g., adjust a gas regulator, close isolation valve) (see Figure R3-10)
R3-2.9 Reduced hlfenlor Exposed Opening Size
R3-2.9.1 The exhaust ventilation volumetric flow rate requirement can alSU be reduced by use of a two-stage
shielding method.
R3-2.9.2 The opening should be sized to allow access to only those components required tor the maintenance or
service task.
R3-2.9.3 The designer can then place interior shields (permanently mounted by screws) on mounting blocks within
the enclosure. This leaves small openings in strategic areas for maintenance and service tasks (see Figures R3-I and
R3-I I).
R3-2,*},4 This method allows for each work task area to have its own shield that can be removed only when that
task is being perfonned-
R3-2. l U Removal of (`omponena*s Without Leak Pofenfiof Exterior to Exhaust lfentilofion Enclosures
R3-2.10.1 There are some designs where many of the components have no potential for hazardous leaks. These
cases include situations such as:
long lengths ufwelded piping
large numbers ufeleetronic components
i n n gases not requiring abatement (e.g., No, As, I-le)
pneumatic manifolds and piping used to actuate valves
52
SEMI $6-0707 © SEMI 1993, 2007
semi
R3-2. 10.2 In these cases, many of the non-hazardous colnponents can be placed in an unventilated location adjacent
to the enclosure.
NOTE I: There may be additional requirements
end uscts.
fuT sccondaty containment o f welded piping in some jurisdictions or by some
R3-2.lll.2.l In some cases there may also be a beneficial effect because these components would not be subject to
damage from leaks of the highly hazardous material {e.g.. of corrosive gases) itself when they are not in the same
enclosure.
R3-2. l0.3 This method can frequently he used in the real' control area of wet benches and other wet pl'ocess systems
by separating components that have no list of leaking te.g., monitors, control modules, etc.) into sealed or purged
areas and leaving only the components with leak potential in the ventilated areas.
R3-2,lU.3.l
This method can then be combined with the reduced opening method to further reduce the overall
exhaust ventilation requirement.
R3-2.1 I Inclusion r;fAufomafic Dampers
R3-2.1 I . l There are cases where the designer knows that there is a need for maintenance exhaust ventilation- In
these cases. the designer can achieve two differing levels of exhaust ventilation by incorporating an automatic
damper control.
R3-2,1 1.2 The automatic damper is installed in the main duet branch and is operated by a pneumatic or electric
operator-
R3-2.1 I .3 The damper operator is activated through a switch on the enclosure door that initiates the following:
.
the door is opened
.
the switch breaks a control circuit
*
the control circuit change causes the damper to revert to
11
maximum exhaust ventilation flow is achieved
its Full-open setting
as-2, I 1,4 When the operation is complete. the following occurs:
the door is closed
the circuit rctums to its normally closed state
the control circuit change causes the damper to return to its restTicted exhaust ventilation How position
.. normal operating exhaust ventilation condition is restored. The dynamics of system balancing may cause
sigliilieant hysteresis for this type efdesign
R3-2.I 1.5 End-users should he rtotiticd of the possibility that use of automatic dampers can affect the balance of the
facility exhaust ventilation system,
R3-2. 12 D¢*::ignjiwrA::ce.v.v to Chemical Hazardous Energy Grmnrrni 5.w¢!e:n.v
R3-2. 12.1 AEV for maintenance within the enclosure may not be required if all of the following are provided:
all energy sources can he properly isolated
all highly hazardous materials are evacuated appropriately from the lines
verify isolated valves are not leaking
work proceeds in this non-hazardous manner until the task is complete
all system are recharged and purged if required
NOTE 2: This can he time consuming if there are multiple highly hazardous material or energy :-iourees because of the time
lequired to evacuate and purge lines and to recharge and recheck the lines after the work is complete.
R3-2. 12.2 Enclosures can be designed to segregate exhaust ventilation into functional groups so that maintenance of
one area will not affect the exhaust ventilation of other areas of the enclosure. Effective use of partitions and
enclosure aceessways that segregate systems can reduce exhaust ventilation requirements for maintenance.
53
SEMI S6-D707 © SEMI 1993, 2007
semi
R3-2 .13 Modularizing Wea' Burl: Sjisfeiris
R3-2. 13.1 The wet bath system is another major user of exhaust ventilationR3-2. 13.2 Exhaust velltilatioll for these systems can sometimes be optimized by use of the following methods:
|
separating each process bath into its own module
* reducing the bath surface area
.
providing automatic bath cover
* reducing the volatility of the SOC where feasible in conjunction with the process (this usually means using the
lowest tempeiature necessary to perform the process)
R3-2. 14 Considerarionsfor Liquid Si's!€t1r5 and Ven! Lines
R3-2.14.1 Duct connection configuration should be such that liquid spills or releases within the equipment
enclosures will not enter the facility's exhaust ventilation systems.
R3-2.14.2 Vent lines for holding tanks, mixing vessels or pressure vessels for hulk delivery are intended to provide
a means of relieving pressure during tilling operations, allowing free flow while liquid is transferred to other
portions of the equipment. They are also used during service procedures such as replacing bulk chemical canisters
and maintenance procedures on chemical delivery systems.
R3-2.l4.2.l Vent lines are typically connected to exhaust ventilation systems to prevent fugitive emissions from
entering the work place
*
R3-2.141.2 Iloldinsum
be vented into qui P
exposure hazard.
wllllll mdlzlnnlillntu
R3-2.14.23 The vent
following conditions
the tank/vessel is over filled
11
bulk chemical deliverly system fails
1 highly hazardous material should not
don, material degradation or personnel
de_test the presence of liquid under the
1
the container's high level sensor fails
R3-2. 14.2.4 The device should he interlocked to put the equipment in a safe state. This sale state will depend cm the
design of the equipment, and may involve depressulizing pressure vessels, closing supply,f,"transller valves. draining
the contents of the container. An error message should he provided to help maintenance personnel detect and correct
the problem.
R3-2. 14.3 Dum' Cnnmtnrrirm Configurations
R3-2.14 .3. I Exhaust ventilation connections made at the top of the equipment are inherently less likely to
contlibute to liquids releases affecting facility exhaust ventilation systems than exhaust ventilation colinectioxis
made al the bottom o f the equipment.
R3-2.14.3 .2 Exhaust ventilation connections made at the bottom of the equipment may contribute to liquids
collecting in the facility duct work. Steps should be taken to prevent damage or safety hazards due to liquid
chemicals collecting in, or being transpolted by, the exhaust ventilation system. The prefetTed design approach is to
prevent liquid process chemicals from entering the duct by incorporating such design features as:
• side mount exhaust ventilation connection at an elevation higher than the depth of the
worst-case leak in the
equipment's secondary containment
bottom mount connection with the air intake elevated above the depth of the worst case leak in the equipment's
secondary containment
• baffles to prevent spraying chemical from accessing the air intake
R3-3 Dampers and Blast Gates
R3-3.1 The number of equipment dampers and blast gates should be minimized.
SEMI $6-0707 @ SEMI 1993, 2007'
54
semi
R3-4 Interlocks and Monitoring
R3-4. 1 Leak Defecfinn
R3-4. l.I Leak detection sensors should usually be located at the entrance to the exhaust ventilation duct, or in the
exhaust ventilation duct before in joins with any other duct.
R3-4. 1.2 Sensor locations may dilTer if dilution of the leak could inhibit detection.
R3-4. 1.3 Any enclosure with plumbing that has the potential for creating gas or vapor releases during maintenance
{or prior to maintenance without capability ofwalning the maintenance person) should be designed with one of the
following options:
C
sufficient exhaust ventilation to protect personnel from releases expected during maintenance work
'I'
AEV to protect workers from releases expected during maintenance activities
R3-4.2 Flow Monitoring
R3-4 ,2.1 A flow monitor will sense more, not less, flow when a door or other aceessway is opened.
R3-4.2.2 There are three reasons why a flow monitor would give alarms:
.
the main factory system loses exhaust ventilation
the local branch damper closes and the process equipment therefore has no exhaust ventilation
a sufficient area of baffles and louvers are simultaneously blocked and air cannot flow
R3-4.2-3 Exhaust ventilation How monitoling is the most effective way to monitor exhaust ventilation and reduce
the likelihood o f alarm from exhaust ventilation fluctuations.
R3-4.3 Static Pressure Monitoring
R3-4.3.1 Static pressure monitoring is susceptible to fluctuation and alarms when:
an adjacent branch demand is changed
dampers in other parts of the system are changed
..
.
.
'I
.
doors or aeeessways are opened
taetoly system static pressure changes
factory system loses exhaust ventilation
local branch loses exhaust ventilation
work in the taetory causes someone to place 8 new opening in a main branch duet
R3-4.4 Cnndffinns Al}"ee.rfng the* Operation of Flow or Static* Pressure Mfmifnrfng Devices
R3-4.4.l
Fxhaust ventilation monitoring devices operating in hostile environments can be rendered inoperable
.'
|.
l
1
without exhibiting obvious signs of failure.
R3-4.4.2 Rugged tubing and corrosion or deterioration of internal parts are two causes of 1"ailure.
R3-4.4.3 If exhaust ventilation monitoring devices must be used in these environments steps, should be taken to
prevent plugging and internal corrosion.
R3-4.4.3.1 On: method that has been used to achieve this result is to purge the sampling line with a low flow of
inert gas controlled by a needle valve. It must he recognized that the reading provided by the monitoring device may
be affected {app-ear more positive) if this method is used.
R3-4.5 Exhaust Ventilation Alarm
R3-4.5.1 Exhaust ventilation alums can take two folks, wanting and shutdown.
R3-4.5.2 A warning can be sounded at a point when the equipment is still safe to operate but is approaching a level
at which shutdown is imminent. The intent is to alert the operator that there is a possible problem with the exhaust
ventilation and that the appropriate maintenance group should be contacted. Failure to do so could result in
equipment shutdown and lost production. The waring should be an acceptable percentage above the equipment
55
SEMI $6-0707 © SEMI 1993, 2007
semi
supplier"s design specification {e..g., l 20% design CFM, 140% design static pressure). The percentage depends on
the exhaust ventilation fluctuations due to turbulence. Depending on the location of the exhaust ventilation
monitoring sampling point. the equipment supplier may not have complete control of exhaust ventilation
fluctuations. The example values mentioned above should work in moderately turbulent conditions.
R3-4.5.3 A shutdown involves an equipment interlock function in which the equipment is placed in a safe state if
the exhaust ventilation falls below a predetermined set point. The set point is typically the exhaust ventilation design
specification established by the equipment supplier. This requirement would be based on a safety engineering
evaluation such as tracer gas analysis (TGA), industrial hygiene sampling or other accepted methods of determining
a safe level of exhaust ventilation at which the equipment should be operated.
R3-5 Exhaust Ventilation Optimization
R3-5.1 Equipment exhaust ventilation design can attempt to reduce static pressure losses caused by: friction losses
from materials, openings, and duct geometries (elbows, duct expansions of' contractions); tLlrbulent airflow; fans,
internal fittings such as blast gates and dampers, and directional changes in airflow.
R3-5.2 Other good design principles include minimizing distance between the source and hood, and reducing
enclosure volumes.
R3-5.3 For non-chemical issues such as heat from electrical equipment, heat recapture rather than exhaust
ventilation may be appropriate.
R3-5.4 The possible impact of highly directional laminar airflow found in most falls should be considered when
designing equipment exhaust ventilation.
R3-5.5 Minimizing the Number and Size of Doors and Other Openings
R3-5.5.1 Compartmentalizing the enclosure so that access to one area does not affect airflow control in other areas
should he considered. Compartmentalizing allows the exhaust ventilation to he adjusted for the hazards in each
compartment. Additionally, eompaltmentalizing allows the exhaust ventilation to he adjusted in a compartment
during maintenance or service operations to address hazard to personnel working in that area.
R3-5.5.2 Accessways should be as small as practical to allow the work required. The use of multiple doors may be
desirable to reduce fluctuations and capture demand.
R3-5.5.3 Designed exhaust ventilation openings such as louvers or battles should be placed to provide the best
cross~flow exhaust ventilation. Other items can improve functionality and eiiieieney of exhaust ventilation,
including4
I
Scdllllg
of unnecessaly openings (2-g.. seams, utility holes] prevents misdirection or
"s
holt-circuitixlg" of the
3iIIUW
.
I
elimination of 90 degree angles in exhaust ventilation system duets
placing louvers and openings lo the enclosure in the aceessway can minimize requirements for footprint or
supply air
NOTE 3: Air volumes as low as 4-5 air changes per minute or less can be specified and meet the SEMI $2 criteria in § 23 if the
design principles listed above are considel'ed when designing equipment and enclosures.
R3-5.6 Exhaust ventilation requirements for such enclosures can be dramatically reduced if:
41
the area of the aeeessway is minimized
• doors are not be dependent un each other, i.e., opening one door should not open, or require opening, another
* enclosures and their contents are designed such that components reasonably foreseen to be the sources of
directed discharges [e.g., pressure relief valves, relief poles on pumps) will not direct such discharges through
an aeeessway, even if the accessway must be open during maintenance or service
NOTE 4: This can be accomplished by placement or otienlalion of such components or be the use of shields or batTles.
|
plumbing within ventilated enclosures is designed, installed and maintained in a manner that directs potential
leaks away hum the aeeessway
SEMI $6-0707 @ SEMI 1993, 2007
56
sem
I
*.
R3-5.7 Velocities through open aecessways of enclosures should be 0.75 to I 1ru's (150 to 200 IiJln} depending on
the vapol' or gas density).
NOTE 5: These velocities au: based on industrial hygiene and vapor modeling criteria. Certain jurisdictions may require specific
velocities above the amount necessary to capture the vapor or gas.
R3-5.8 Any enclosure that contains equipment with a failure more frequent than SU() hours Mean Time Between
Failure (MTBF) (e.g.. diaphragm pumps) should be provided with sufficient exhaust ventilation to provide. with the
aeeessways closed, capture veloeitjv tor vapors that can be liberated when the component fails.
H3-6 Primary Exhaust Ventllation (PEV)
R3-6.1 Process Effluent Streams Separated frnm the Atmosphere
R3-6. l.l Design of exhaust ventilation systems where the source is not open to atmosphere is a special ease.
R3-6. 1.2 Systems include:
G
reduced pressure chambers for deposition
*
reduced pressure chambers for etching
•
reduced pressure chambers for cleaning
I
Iilmaces and other processes under vacuum
R3-ti. I .3 Exhaust ventilation should be designed to properly manage the following actions:
entrainment of contaminants
capture all process materials and byproducts
prevent build-up of materials in foreline and pump collnectiuns
R3-6.1.4 Exhaust ventilation systems that produce solid contaminants should be designed so they may be
disassembled and cleaned as necessary to remove the residue.
R3-6.1,4.1 Systems operating at high temperature may produce substances that adhere to the walls of the exhaust
ventilation system upon cooling.
R3-6.1.4.2 Such systems should he provided with a procedure for cleaning components that become plugged.
Alternatively. a means should be provided to ensure conveyance o f the .gaseous contaminant to a device where it is
intended to condense and collect.
R3-6.1.5 Systems that produce solid byproducts may require multiple means of managing the effluents, one system
to manage the solids and another to manage the gaseous effluent. See SEMI F5 for advice on types of systems.
R3-6. l .6 When toxic or highly toxic gases are used in the process or generated as byproducts, additional ventilated
enclosures may be required to manage the pumps and eMuent connections adequately.
R3-6.1.6.1 In such eases, pump eMu-ent connections should be contained within a ventilated enclosure and
provisions made for monitoring for gas leaks according to SEMI $2.
R3-6.1.7 In all systems. materials of construction should be designed to he compatible with the process effluent and
the heat that will be generated in the process.
R3-6.1.7.1 Certain S(}Cs [such as chlorine) require special materials for compatibility.
R3-6.1.7.2 Gasket and seal materials require both chemical and thermal compatibility to prevent deterioration that
may cause leaks.
R3-6.1.3 The supplier should specify torque requirements if they are necessary for safe assembly of effluent line
components.
R3-6. l .9 Monitoring of exhaust ventilation should be performed at a point that is upstream of the first damper from
the process equipment or pump to ensure that a closed of' defective damper is detected.
R3-6.1.10 Static pressure monitors in the ductwork will not sense plugging in the exhaust ventilation line, or in the
scrubber. Velocity pressure monitors may not detect plugging in the exhaust ventilation line or the inlet of the
57
SEMI $6-0707 © SEMI 1993, 2007
semi
scrubber if the scrubber has high NO or compressed air Flows- In such cases, on SME using highly toxic gases or
toxic gases with poor warming properties (e.g., CU, NFL}. the effluent line between the pump and scrubber should be
monitored fer negative pressure. The monitoring device should:
•
be capable of providing an external interlock alarm.
•
be capable of withstanding pressure tTansients,
»
resistant to plugging and corrosion, and
.. incolporate a time delay function that allows the interlock to ride through pressure tlansients caused during
chamber pump down and or maintenance procedures such as flow calibrations.
R3-6,2 Prnc'rr_c.s~ Ejfuent Streams Mixed with Atnztwrpixerir Air
R3-45.2. I Open Surface Tank Equipment t We! Stations)
R3-62. I .1 Wet stations should he designed to capture emissions from open surface tanks or baths.
R3-6.2. I .2 Because wet stations may he open on the front, top or any side, enclosure is a key concept in wet station
design.
R3-6.2.1 .3 Slots should be provided uniformly along the length of the hood for even distribution of airflow.
R3-6.2.1 .4 Additional lip exhaust ventilation slots should be provided around tanks or sinks to control emissions.
R3-6.2.1 .5 The plenum behind the slots should be sind tn:nlm'=:w=n
should he designed to ensure that adequate airflow is pi nrviducl bvthu
could reduce exhaust ventilation performance.
lltion of static pressure. These slots
l1n1s and to minimize turbulence that
R3-6.2. LE Velocity along length of slot should not vary
'velocity
I
R3-t'1.2.l.7 Exhaust ventilation should be designed to I
from exposure.
r
.-
R3-t'i.2.l .7.1 Enclosed processing tanks or h Jill:~ may raqlmia
rinsing of the chemicals, or to control humidit.
to protect personnel
on to control vapors released from the
R3-6.2. I ,7.2 Calculate the: total exhaust ventilation volume requirement (either by tank. by module or for the entire
system) by detelmining the total volumetric flow of laminar air reaching the combined face of the wet process tanks
or baths (at the sulface of the tank or bath) and providing exhaust ventilation volume at that level plus 20 to 25%.
R3-6.2.1.8 Exhaust ventilation volume settings should consider laminar airflow volumes and be balanced to
minimize turbulence and to ensure capture.
R3-6.2. I .0 The station design should consider airflow patterns in the operating zone to minimize turbulent
horizontal ailtlow patterns into and across the work deck.
R3-ti.2.l.9.l Wet stations can be partially enclosed from the top or sides to reduce the impact of side drafts or
downward laminar airflow. In such cases. at artificial plane opening {"face"} can be defined. The point where the
clcan1oom...s downward laminar airflow meets the exhaust ventilation horizontal How. This is identified as the
capture zone the "tace"l of the wet station,
R3-6.2- I .IU Depending on the hood design and laminar airflow provided, average face velocities can range Hom
0.20 to 0.75 nuts (40 to IS() fpm}. The specific value selected depends on the characteristics of the contaminant
including toxicity. how it is released 1e.g., vapor, mist. solid), generation rate. and release velocity. Other factors
such as room turbulence, hood size also should be taken into account, Refer to lndunrfuf Venrifafiion Hood Design
Factors for further guidance.
R3-(i.2.l .1 l Additional considerations to reduce exhaust ventilation demand include providing covered tanks, and
recessing tanks below deck level.
R3-6.2.2 Ow.ns
R3-6.2.2.1 Ovens used for drying, baking or testing semiconductor products pose a special exhaust ventilation
challenge. This equipment operates at a slight negative pressure or in some cases positive pressure. Operators have
SEMI S6-0T07 © SEMI 1993, 2007
58
semi
direct access to the oven chamber when product is inserted or removed. Process chemicals or byproducts may be
health hazards or create noxious odors. Consideration should be given for capturing these materials.
R3-6.2.2.2 Ovens should be designed to prevent process chemical or byproduct vapors from escaping into the work
area during normal operation and when the door is opened tor product handling.
R3-6.2.3 Chemical Luhnratrny Fume Hoods, Parts Cleaning Hfaods
R3-6.2.3.1 Hoods should he fully enclosed on five sides, open on one side for access and pmcessfpaM placement
and removals.
R3-1.2.3.2 Front (access side) should be provided with sliding door or sash.
R3-6.2.3.3 Minimize size of the hood based on process size.
R3-6.2.3.4 Minimize front opening size based on size of process and employee access needs.
R3-6.2.3.5 Ensure hood construction materials are compatible with chemicals used.
R3-6.3 Validation
R3-6.3.1 For accurate measurement and confirmation of overall effectiveness, the "face" of the wet station should
be divided into a grid of o.1m1 (one square foot) sections. The velocity in each section should then he measured.
Capture (face) velocities are calculated by averaging all of these measurements and verifying that the overall
average meets the criteria and no single section measures below a calculated minimum level.
R3-6.3.2 The measurement location can greatly intiuenee the measured Face velocity. therefore, face velocity
measurement should be supplemented with capture velocity calculations or total volume calculations and
measurements tor accuracy and reproducibility at the user's facility.
R3-6.3.3 Pel'fomlance of the exhaust ventilation should be tested by fugitive emission analysis and documentation
should confirm that chemical containment meets the exposure criteria of SEMI $2 at distances beyond the plane of
penetration at the exterior o f the wet station.
R3-6,4 Mnrzitnring and l'ntr'rlr»r*ks
R3-6.4.1 Wet station controls are complicated by the fact that wet stations may not have an easily definable location
to continuously monitor tice velocity.
R3-6.4.2 The method used should be consistently applied and documentation providedR3-6.4.3 Whichever method is used, the controls should shut oft the sources o f the hazard {e.g., close covers, stop
chemical pumping of' filling) when exhaust ventilation falls below minimum calculated safe levels.
EXCEPTION: Time delays may be allowed in order to account for fluctuations in exhaust ventilation provided they
are not long enough to create an exposure risk (typically 10-30 seconds for open face systems). If the system is
contained by the equipment design, longer delays may be allowed if testing shows the exposure is contained.
Testing, should be performed to verify the safe duration of the time delay.
NOTE (1: Users generally have spec iications about allowable delay times.
R3-6.4.4 Open-surflace tank and bath systems that do not have self-closing covers should be designed to drain the
tank or bath when exhaust ventilation fails. This reduces the release of vapors and can prevent corrosion.
EXCEPTION: In the case of certain heated tank systems, automatic covers or draining to cooling tanks may he
necessary to prevent dumping hot chemicals into drains where chemical or thel'mal reactions may comprise
additional hazards.
R3-6.4.5 Monitoring may be accomplished by measuring static pressure by use of a device such as a pressure
switch. Monitoring devices should he capable of displaying the actual pressure or flow and the alarm set point.
(These features are important to facilitate maintenance checks and calibration of the sensors and verification of
alarm set points.)
R3-t'i.4.5.l Pressure sensors can give incorrect readings if their sensing point is placed in a location where a closed
damper or device ensures that there is always static pressure. Therefore, these devices should always be placed
59
SEMI $6-0707 © SEMI 1993, 2007
semi
upstream of any exhaust ventilation isolation device to ensure that the measurement reflects the true pressure o f the
SME ventilation system.
R3-6.4.6 Monitoring may also be accomplished by use oflvali¢Jus lypcs of flow switches.
R3-6.4.6.1 A typical method is to use a pilot Mba: arrangement that measures pressure in two calculated paths of the
airflow and uses the TWD measurements to create a flow measurement.
R3-6,4.6,2 Any method may be acceptable provided the device is compatible with the exhaust ventilation stream
and does not detel'iol'ate from the environment.
R3-7 Secondary Exhaust Ventilation (SEV)
R3-7. I Gvnvrua' C`rm.':ide'ru!rlnr1a'
R3-7. I . I SEE is intended to be a control measure in the event a chemical is released from its primary containment.
R3-7,1 .2 SEE is typically provided for the following types of enclosures,
* gas source
.
.
I
gas handling (e.g., equipment gas panel)
gas-phase process chambers
liquid source
.
'I'
liquid handling
liquid-phase procell
R3-7.1.3 Minimizing I
and its enclosure will reduce the volume
of exhaust ventilation r
R3-7.1.4 Minimizing
IJ10 reduce user's system demands. The
|
enclosure should be delignndsnflaat lldnqulllan
don can be obtained with static pressure
within the range of -180 to -$550 Pa. ('-0.55 to -1.S "w.g. at the point ofconneelion to the facility)
NOTE 7: Excessive static pressure produces hazerdl
umnlnuunduur opening and closing
R3-7.1.5 Enel<Jsul'es should be designed m ]
example ofsueh a design.
r
stagnation. Figures R3-3 through R3-6 depict an
R3-7.1.6 Where routinely used aecessways are required. provide baffles behind the door to direct leaks away from
the door and openings.
R3-7.1.7 Where multiple SOC are in
Lise,
enclosures should be comparttnentalized to isolate potentially
incompatible gasesivapors.
R3-7.2 Validation
R3-7.2.1 Sampling for fugitive emissions (either directly or by releasing a tlaeer gas) can be used to verify control
of liigitive emissions. See § s for details.
R3-7.3 Mnnfrnrfng and !nI¢*r!ork.r
R3-7.3-1 See "Monitoring and interlocks" in § R3-6 above.
R3-8 Additional Exhaust Ventilation (AEV)
R3-3. l bQt'huus! l"w:l'ilnliofi jiir l'l4uin{¢*rurm'e or Sevwfiee
R3-S.l.l Maintenance and service exhaust ventilation may be provided as pant of the equipment design or as a
separate AEV system requirement.
R3-3.1. I , l Exhaust ventilation should not he relied upon to prevent exposures to hazardous substances with
significant release velocities leg., pressurized liquids and gases).
NOTE 8: PPE or procedures {e.g.. hazardous energy isolations which remove the hazard may be required.
SEMI $6-0707 @ SEMI 1993, 2007
_
60
semi
R3-3.1-1.2 AEV can be provided by a Flexible duct with a tapered hood, either designed into the equipment or
provided by the facility.
R3-3.1.1 .3 This AEV system can be placed in the work area to remove potential contaminant emissions from close
to the maintenance or service location before they enter the breathing zone. It is recommended that local exhaust
ventilation flex ducts be self-supporting with an internal structure or other' means that allow them to be locked inplace, and not require personnel to support the ducts.
R3-3.1.1.4 Retractable or movable non-combustible flexible ducting can be used for positioning this AEV to
control potential emissions and should include:
I
.
tapered hood with a plain opening as a minimum. Installing a manual damper at hood to allow for local control,
{e.g., shut off when not required)
ducting and hood capable of being placed within 150 mm to 300 mm (6 to 12 inches] of potential emissions to
be controlled
.. u minimum capture velocity of 0.50 m/s (100 fpm) at the contaminant generation point for releases of vapor by
evaporation or passive diffusion
R3-R, I . I .5 AEV Cafcufurinna' - For a plain open ended duct without a hood, the airflow required at a given capture
velocity can be calculated by:
Q=
vuuxz + A )
£RA-I)
where :
Q
required exhaust ventilation airflow in mais (cfm)
v
capture velocity in Ws (fpm) at distance X from hood
A
hood face area in square: meters (square fcctl
X
distance from hood face to farthest point of contaminant release in meters (feet)
NOTE 9: This is accurate only i x is within 1.5 diameters of a round opening. or within 0.25 circumference of a square opening.
NOTE II): This is one commonly used equation. Other equations may be appropriate (see also ACGIH Industrial Ventilation
Manual. and Semiconductor Exhaust Ventilation Guidebook).
R3-R. l . l .6 The additional use of flanges or canopies to enclose the process will result in improved efficiency.
R3-8,2 Vufidulinn
R3-R,2.I Aerosol visualization and velocity measurements may he used as preliminary methods to assess the
effectiveness of the design in capturing contaminants.
R3-8.2.2
Sampling for fugitive emissions (either directly
OI'
by releasing a tracer gas) can he used to verify that
capture is sufficient.
FI3-9 Means of Stopping SOC Flow
R3-9,1 A means should he provided to stop the flow of 8 substance of concern to a leak, from primary containment,
within a ventilated enclosure. The means may be automatic Ol' manual and does not necessarily coliform to the
criteria in SEMI $2 for safety interlocks. Actuating the means should not compromise the ability of the ventilated
enclosure to protect against exposure of personnel above the limits specified in SEMI $2 tor tlault conditions and to
protect against the formation of a mixture of a flammable vapor with air above 25% of the LFL.
R3-9.2 Sourires of SuNsrances it' Concern Outside the SME - As a leak in the plimary containment may be before
the first valve in the enclosure. it should be possible to stop the flow by some valve upstream o f the enclosure. That
valve should be provided with a means of containing leaks from it, such as a separate enclosure leg., a valve
manifold box). The upstream valve may be pan of the equipment, of' it may be e x t r a ] to the equipment. in the
latter case, if a detector is provided by the equipment manufacturer, the equipment manufacturer should provide a
signal to shut off the valve when a leak occurs and specify the provision of the valve as part of" the installation
requirements tor the equipment,
61
SEMI $6-0707 © SEMI 1993, 2007
semi
»-»"\-.
ae
.'
.""
|-
."|
Remotely actuated valve
Facility' flow
control assembly
Inlerlcrck
signal
M a n u a l valve w i t h
handle outside
enclosure
of
|\
.al
.1'
O t h e r fluid
handing
components
in
Leak
'~._del actor
.r
1
S M E Ventllaied Enclosure-
SM E
Figure R3-12
11
Schematic Showing Separate Enclosure Provided be Facility and Interlock Signal from 8
|
.'
Detector in the SME Enclosure to a ¥ a l e in the Separate Enclosure
7
o
Facility fluid feed to S M E
.Ag
|I
r.
R e m o t e l y actuated valve
is
S M E flow c o n t r o l a s s e m b l y
Interlock
signal
"
al#
all*
Ill*
all.
gm
h
t
O
-
Remotely
actuated valve
Leak
I detector
e
Other
fluid
fluid
r
h a n dd Hng
components
ur-
S M E Y e n t l lated E n c l o s u r e
SME
Figure R3-13
"1
Schematic Showing Separate Enclosure Provided be SMF and Interlock Signal from a
Detector in the SME Enclosure Being Described to a `*¢ zlhe in the Separate Enclosure
|
J
U
T
I
r
R3-*?.2.l,2 If the first valve within the enclosure is a manually-actuated valve. it should be possible to close the
valve when a leak occurs without compromising the ability of the ventilated enclosure to provide the specified
protection. This may be by reaching the valve through an aecessway that. when open, does not defeat the ability of
the ventilated enclosure to provide the specified protection. Alternatively. this can be accomplished by providing a
tool for' closing the valve that can be used through such an accessway, or by placing the valve handle outside the
enclosure {see the Note following 8.31, 2.1 }.
R3-9.2.1.3 If the first valve within the enclosure is a remotely actuated (e.g., pneumatics valve, that means of
actuation should be capable of being used to stop the flow without opening the enclosure.
SEMI $6-0707 © SEMI 1 g93 2007
az
semi
NOTE I I : If the valve is under automatic control, it is recommended that the designer of the fluid handling system consider
whether it is appropriate to provide a safety interlock to close the valve upon detection of a leak.
R3-9.2.2 Sources ofSuh.rmnces of Crmcern Within the SME
R3-9.2.2.1 If the substance of COIllC€l'l\ in the soul'ce container is a gas or liquid above atmospheric pressure and is
intended to be provided to the SME above atmospheric pressure, a means of stopping flow from the container. if a
leak were to occur. should be provided.
R3-9.2.2.2 If a container of liquid is operated above atmospheric pressure, a means of relieving the pressure within
the container, if a leak were to occur, should also be provided-
NOTE I2: This criterion peitains. inclusivel y, to containers of liquid that use gas pressure to dispense the liquid.
R3-9.2.2,3 If the substance of coneem in the source container is a gas above atmospheric pressure and is intended to
be provided to the SME below atmospheric pressure by means of pressure regulation within the container; a means
of stopping flow from the container. if a leak were to occur. should be provided.
R3-9.2.2.4 If the substance of concern in the source container is a gas below atmospheric pressure or a gas adsorbed
or absorbed on a solid with a vapor pressure of the gas below atmospheric pressure, a means of preventing air
entering the source container, if a leak were to occur, should he provided. If a reasonably foreseeable single point
failure {e.g.. temperature control failure) could result in the pressure of the gas being above atmospheric pressure, a
means of stopping flow from the container should be provided. The means of preventing air entering the container
and the means of stopping flow may be the same.
R3-9.2.2.5 The means of stopping flow should he a valve incorporated with the corttainel'
valve, the lira valve in the How path from the container outlet.
R3-9.2.3 f€e~:'irr'u!afed Suhstammt
Ur,
if there is no such
of Concern
R3-9.2.3.1 If a substance of concern is to be recirculated within the SME or between a supply subsystem and the
SME in a path that includes a reservoir. a means of stopping flow within the enclosure and at, or immediately
downstream of, the reservoir outlet should be provided.
R3-9.2.3.2 If a substance of concern is to be recirculated by a pump, a means of stopping flow within the enclosure
and at, or immediately upstream of, the pump should be provided.
R3-9.2.3.3 If the reservoir outlet is connected directly to the pump (i.e.. there is nothing but piping and the means of
stopping flow between the reservoir outlet and the pump inletly. a single means of stopping flow may be used to
satisfy the criteria of the preceding two paragraphs.
R3-9.2.3.4 If the means of stopping flow is a manually actuated valve, it should be possible to close the valve when
a leak occurs without compromising the ability of the ventilated enclosure to provide the specified protection. This
may be by teaching the valve through an accessway that. when open. does not defeat the ability of the ventilated
enclosure to provide the specified protection- Alternatively, this could be accomplished by providing a tool for
closing the valve that can be used through such an accessway, or by placing the valve handle outside the enclosure.
R3-9.2.3.5 If the means of stopping flow is a remotely actuated (~€.g., pneumatic) valve., that means o f actuation
should be capable of being used to stop the flow without opening the enclosure.
NOTE 13: In the valve is under automatic control, it is recommended that the designer of the fluid handling system consider
whether it is appropriate to provide a safety interlock to close the valve upon detection of a leak.
R3-9.2.3.6 In addition to the means of stopping flow discussed in the preceding several paragraphs. there should be
a means of removing the energy supply to the pump from outside the enclosure.
NOTE I4: It is recommended that the designer of the fluid handling system consider whether it is appropriate to provide a safely
interlock to remove the supply of energy to the pump upon detection of a leak.
R3-9.2.3.7 If the recirculation is between SME that is being evaluated to this safely guideline and a supply
subsystem (containing a r'eservoir
of'
pump) that is outside the scope of the evaluation, a safety interlock that
conforms to the relevant criteria of SEMI $2 may be provided by the SME supplier to f`ulfill the criteria which
pertain to pumps and valves in the supply subsystem.
63
SEMI $6-0707 © SEMI 1993, 2007
semi
RELATED INFORMATION 4
CONTROLLING OBJECTIONABLE ODORS FROM PROCESS
EQUIPMENT
NOTICE: This related information is not an official part of SEMI $6 and was derived from the work of the global
Environmental, Health & Safety Committee. This related information was approved for publication by full letter
ballot on April 25, 2007.
F14-1 General Considerations
R4-l.l This Related Information does not address emissions that have health and safety implications. Those
situations are covered elsewhere in SEMI $6. in SEMI $2 and other guidelines referenced in SEMI $2.
R4- I .2 Odors can create employee coneems even when there is no associated health hazard. This in tum disrupts
the work etlvil'onment by affecting employee morale by creating eoneems about the work place, and may ultimately
affect plnductivity.
R4-2 Controls
R4-2, l The TbIlowing hierarchy should be used in addressing odor concerns:
R4-2. l . I Eliminate, or substitute something for, the chemical{sl that cause the odor.
R4-2. l .2 Modify the process so that these chemicals are nuut vnllntllind,
L
nun The work area
R4-2.1.3 Design engineering controls that prevent the l
R4-2.2 The first two options in the list are beyond 1
aiddlesscd.
Only the third option will he
R4-3 Engineering Controls
R4-3.1 The tallowing are some example S of considerations for the control of odors when the SME is designed as a
closed system.
R4-3. l .I Maintain the SME's process chamber at negative pressure with respect to the work area.
R4~3.1.2 Assure that the process chamber is leak tight.
R4~3,1.3 Choose chamber seals that are compatible with the chemicals and easy to clean thereby preventing leaks
caused by degradation of the seals and chemical buildup on the mating surfaces.
R4-3.1.4 Providc a chamber exhaust ventilationfpuigc of sufficient volume and duration to assure that the chemicals
are flushed from the process chamber and do not escape into the workspace when the chamber is openedR4-3.1 .5 Avoid using circulating fans or blowers that push the chemicals out into the work area when the chamber
is opened. Alternatively, interlock the fanf»'blower to prevent it from operating when the chamber is opened.
R4~3.2 In some cases the SME openiting palumeters may not allow opelutiou at subatmospheric pressure or
adequate purging. The following are some examples of design considerations for the control of odors using external
exhaust ventilation,
R4-3.2.1 Curing Ovens - Bake out or curing ovens are typically used harden coatings such as photoresist or
polyimide on wafers. Solvents and other volatile fractions may be driven oflt` dining the process. Some of the
chemicals that are volatilized prepuce a strong, objectionable Mor at relatively low eonccnnations. Equipment
suppliers should consider this in their designs.
R4-3,2.I,l Enclose the ehamher of the SME with suitable material and provide sufficient exhaust ventilation to
capture emissions from the SME.
R4-3.2. I . l . l The enclosure should allow ample access to the SME for maintenance and service.
R4-3.2. l .L2 The material used for the enclosure should not present additional hazards {e.g., fire).
SEMI S607D7
@
SEMI 1993, 2007
64
semi
R4-3.2.1.2 The process chamber door area of the SME should be provided with a sufficient pelipheral exhaust
ventilation to capture emissions escaping during processing and when the door is opened for removing product. The
specific design will depend on several factors:
'I
use. placement, and air velocity of laminar airflow hoods
¢
laminar airflow versus cross drafts
l
dimensions of the process door
•
dimensions of SME
-.
dilution concentration required to control the odor
I
temperature of process gases when door is open
R4-3.2.2 Vacuum Pumps and PoemJ-of-Use l'POU) Scrubbers
R4-3.2.2.1 Enclose the pump or PDU scrubbers with suitable material and provide sufficient exhaust ventilation to
capture emissions from the equipment.
R4-3.2.2. I .I The enclosure should allow ample access to the SME for maintenance and service.
R4-3.2.2. 1.2 The material used for the enclosure should not present additional hazards (e.g., firelR4-3.2.2.2 The enclosuretsl should contain the connections to the pump eMuent line and to the POU abatement
equipment.
R4-3.2.2.3 Ideally the line between the pump and scrubber would be short and of solid welded construction.
However due to logistical and maintenance issues this is not always possible. in cases where it is not possible,
regular preventative maintenance should he conducted on gaskets to ensure that the seals are in good condition and
that the joints are tight. See also 11 R3-6. l .l.lf).
R4-3.2.3 Wafer Coating Equipment (e.g.. plum resist, polyiinide, antirej?ec'!ive coming)
R4-3.2.3.1 Enclosures containing coater bowls. associated plumbing and components wetted with process
chemicals should be designed with sufficient exhaust ventilation to maintain the enclosure at a negative pressure
with respect to the work area.
R4-3.2.3.2 SEMI $2, Appendix 2 provides design and test parameters for chemical dispensing cabinets. These
parameters should be applied to the enclosures mentioned in 11 R4-3.2.3.l above.
R4-4 Design Examples
R4-4,1 Figure R4-I depicts an example of a design that was successliilly used to control emissions from a large
oven. It is a modified "push-pull system combined with periphel'al slot exhaust ventilation. The air volume and
velocity being drawn into the enclosure at the front of the SME was sufficient to capture fugitive emissions from the
door. The air passing through the enclosure also prevented emissions from the process chamber in the chase from
escaping into the work area. The front of the SME (operator side) was located in a laminar flow hood. The return ail'
path for a normal bay and chase design is under the wall into the chase. In this situation the return air' paths were
blocked. The downward laminar flow of air helped drive the emissions to the enclosure exhaust ventilation inlet at
the floor, preventing them from ii:-circulating from the chase back into the work area.
R4-4,2 Figure R4-2 depicts an alterative design using a knife-edge air supply above the front of the oven to
increase the sweeping action over the work area. Depending on the cleanliness requirements, a HEPA filter could be
installed in the path of the supply air.
65
SEMI S6-D707 © SEMI 1993, 2007
semi
,,WALL
'I I'
or
'\ I
I
'If
A
"1
\.
I
.*
`1
ENCLOSURE
EXHAUST
DUCT
v
1'
AIR
INLETS
I
I
I
I
I
LAMINAR
AIR FLOW
I
I
I
I
I
CNEN
FRONT
PROCESS
EXHAUST
SIDE nEw
VENTILATED
ENCLOSURE
Figure R4- I
Ventilated Enclosure for Uvcn Using Laminar Flow
SEMI $6-0707 © SEMI 1993, 2007
B6
semi
I
BLOWER AND
HEPA FILTER
of,WALL
AIR
INLETS
I
I
*In
ENCLOSURE
EXHAUST
DUCT
PROCESS
EXHAUST
SIDE VIEW
OVEN
vEr~mLA7Eo
ENCLOSURE
FRONT
I1
11
were
Figure R4-2
Ventilated Enclosure for Oven Using PushfPull System
67
SEMI $6-0707 © SEMI 1993, 2007
semi
RELATED INFORMATION 5
RECOMMENDED FORM FOR REPORTING EXHAUST VENTILATION
INFORMATION
NOTICE: This related information is not an official part of SEMI $6 and was derived from the wo|Jk of the global
Environmental, Health & Safety Committee. This related information was approved for publication by full letter
ballot on April 25, 2007.
H5-1 Information
R5-l .1 SEMI $2 and this safety guideline state that certain infolmation regarding exhaust ventilation specifications
should he provided to end users. This inliolmation should be provided with the equipment installation instructions in
order that equipment is installed correctly and adequate safety exhaust ventilation provided. This intonation
includes:
equipment description and configuration
the information dess:l'ihed in Table R5-I
CIC
www
SEMI $6-0707 © SEMI 1993, 2007
68
semi
Table R5-1 Exhaust Yentilation Specifications Data Table
Connection Connection Connection Connection
Drawing Number and Conllecliuu Number
I
I
I
I
I
Connection label
Static Pressure *
.Minimum
Maximum
Maximum aceeptoblefluctuotion
Flo iv:
Process Average Flow
Idle Average Flow
Type
of Exhaust ventilation
(e.g., Corrosive, Ftammubte, Toxic, General)
Purpose of Exhaust ventilation
(e.g., Safety, Smoke Rernovat, Hear)
Facility exhaust ventilation Duet Speciticotions
SME Fitting Thorpe
Size
Materials of Construction
Location
of Internal' Dampers
Exhaust ventilation interlock
Setpoint
Monitoring Device Location
Time Delay (duration in seconds)
Duet Measurements:
Location
Method Used to Make Exhaust lfentitation Measurements
(e.g., pitat traverse, hot wire anemometry)
Process Emissions:
Chemistry
(Identity, Physics! state and % Weight or
Volume of each component other than Dr)
Maximum Temperature
Performance Criteria:
Face I/etoeitjv
Capture Velocity
Duct Velocity [for partietes)
External Damper Required
Comments
69
SEMI $6-0707 © SEMI 1993, 2007
semi
RELATED INFORMATION 6
GENERAL EQUATION RELATING PROCESS GAS FLOW RATE TO
TRACER GAS INJECTION RATE
NOTICE: This related information is not an official part of SEM] $6 and was derived from the work of the global
Environmental, Health & Safety Committee. This related information was approved for publication by full letter
ballot on April 25. 2007R6-I in this related information, a generral equation relating process gas flow rate, tracer injection Flow rate, and
measured tracer gas concentration outside an enclosure to the ERC is provided. In the following, Q and L are given
in units of volume per unit time- Concentrations: C are given in units of either volfvol. or %- Whatever units are
chosen should be used consistently in Equation R6-7.
R6-2 Let the tracer gas injection rate into a volume be Q and the exhaust ventilation rate in this volume be L. At
equilibrium, the concentration of tracer gas within this volume is QIL : Cmurre- Ii in the laboratory, one measures a
concentration of tiacer gas CrH.b. then the Dilution Ratio, D, can be calculated as equal to
C:aJCw..f.-
]l|i.cEr
=
D!nlr'fr
l
For any conserved chemical specie. D is constant. Thus, for a process gas released within the volume, one can font
an analogous ratio
1R6-23
Ci'¢rb C'1vnrr¢' .
For all conserved chemo' of I
|
D is constant, hence
{R6-3)
Drl'arrJ'l
From this, one can tbnri
C.'rah*"Cs-nur-f'r ]tTy»::r
(R6-4)
l
So that
Cfaib Cwurrr
Here Club
]pl1o¢:ss
lm:
x
Csrieimr lpruceu = Club iprucrns
(R6-5)
is the previously identified ERC.
For releases in the same test volume, this equation can be written
l Club llrauer >-: lQ»"fJ]pm.¢H' {Q"I[*l]`|l'.CCr = ERE
IRE-6)
As the exhaust ventilation rate is the same
Club lllucet K Q1x:'rl('¢-ti
Qrrarvr =
ERE
£R6-73
This equation allows the calculation of ERC when simulating a leak within an enclosure using a dilterent diameter
tubing or different tlowtate. In the ease where the flowrates for tubing size length and injection pressure) al'e the
same for the tracer and the process gas. Equation R6-7 simplifies to that in § A2-4.
SEMI $6-0707 © SEMI 1993, 2007
70
semi
RELATED INFORMATION 7
EXHAUST VENTILATION AS SMOKE CONTROL
NOTICE: This related infonnatien is not an official part of SEMI $6 and was derived from the wol1< of the global
Environmental, Health 8: Safety Committee. This related information was approved fel' publication by full letter
ballot an April 25. 2007.
R7-I The considerations in this related information are relevant only i f the exhaust ventilation is intended to control
or manage smoke.
R?-2 Exhaust ventilation may he used to reduce the risk from tire by controlling the behavior of the products of
combustion. (See SEMI $2 arid SEM] $14 for discussion of this.)
R7-3 Effective smoke control exhaust ventilation is capable ofrcmoving the products of combustion from the
enclosure in which a fire is foreseen and mitigating their spread to other parts of the equipment
equipment.
of'
to outside of the
R7-3.1 The specific pertOirnance requirements are determined based on the desired risk reduction.
NOTE l: Smoke control system criteria (when exhaust ventilation is designed for that purpose) may be defined by local
regulatory agencies.
R7-4 Exhaust ventilation for smoke control may be provided by any of several means:
R7-4.1 Smoke control may be an occasional function of exhaust ventilation that is provided for other purposes.
R7-4.2 Exhaust ventilation may be provided continuously for the explicit purpose of smoke control.
R7-4.3 Exhaust ventilation may be provided for smoke control and activated only when smoke is detected.
R7-5 Exhaust ventilation solely tor smoke control may require treatment to eliminate partieles or other products of
combustion.
R'7-6 Adequacy of smoke removal by exhaust ventilation is determined by assessing the risk due to fire with and
without the exhaust ventilation. SEMI $14 provides guidance on how to assess the risk under various conditions.
R7-7 Considerations in Designing a SME Srtioke Con!m.{!Rer1*rovnf S.i'si*em
R7-7.1 Dedicated smoke control removal systems are not typically found on individual pieces o f SME. Any smoke
removal from SME is usually accomplished by exhaust ventilation provided for some other purpose.
R7-7.2 Existing SME exhaust ventilation systems can be expected to remove the smoke from only low intensity
fires bless than ltlflkwl contained within the SME. Once a fire breaks out of a piece of equipment (tor example,
through the horizontal working surface o f a wet bench), smoke control has essentially been lost.
R7-7.3 There may be various compartments within a piece of SME that have no exhaust ventilation and hence no
smoke removal capability.
R7-7.4 There typically arc compartments in SME that have only "general ventilation" and arc not connected to an
exhaust ventilation system intended to receive contaminated air. An example is electrical equipment cabinets- The
general exhaust ventilation ductwork and its connection to the SME may not be reliable for' smoke removal if
exposed to a fire within the SME.
R7-7.5 When the SME exhaust ventilation system is also to serve as the smoke removal system, the following
features have been shown to enhance performance:
R7-i7,5.I The exhaust ventilation ductwork is comprised of materials that are non-combustible or are eertitied by an
accredited testing laboratory for smoke removal.
R7-7.5.2 The exhaust ventilation ductwork does not incolporate the use of fire dampels or intenupters.
R7-7.5.3 The ductwork remains connected to the SME and does not collapse in the event of a fire in the SME.
71
semi
SEMI S6-D707 © SEMI 1993, 2007
NOTE 2: [f the SME is combustible. a fire sprinkler may he needed in the ductwork as close as possible to the connection to the
SME {la,tpica]ly within 0.6 m 12 feet) according to fire codes).
R7-7.5.4 [t is undesirable to use flexible duct connections, other than those that are listed or approved for the use, to
connect the exhaust ventilation duct to the SME. They are likely either to bum through or to collapse if exposed to
heat or direct flame impingement from a fire within the SME.
NOTICE: SEMI makes no warranties or representations as to the suitability of the safely guideline(s) set tbrth
herein for any particular application. The detemiination of the suitability of the safety guideline's) is solely the
responsibility of the user. Users are cautioned to refer to manufacturer's instructions, product labels, product data
sheets. and other relevant literature respecting any materials or equipment mentioned herein.
These safety
guidelines are subject to eliange without notice.
By publication of this safety guideline, Semiconductor Equipment and Materials International {SEMlI takes no
position respecting the validity of any patent rights or copyrights asserted in connection with any item mentioned in
this safety guideline. Users of this safety guideline are expressly advised that determination of any such patent
rights or copyrights, and the risk of inttingement of such rights are entirely theil' own responsibility.
us
up
SEMI $6-0707 @ SEMI 1993, 2007
72
Copyright by SErIf (Semiconductor Equipment and
Materials International). 3021 Zankcr Road. San Jose. C A
c§I5134. Rcl:n'n»du»:timt of the contents in whole or in pan is
forbidden 'without express written consent of SEMI.