PROCEDURAL
STANDARDS FOR
FUME HOOD
PERFORMANCE
TESTING
2009 – FIRST EDITION
NATIONAL
ENVIRONMENTAL
BALANCING
BUREAU
PROCEDURAL
STANDARDS FOR
FUME HOOD
PERFORMANCE
TESTING
2009 – FIRST EDITION
National Environmental Balancing Bureau
8575 Grovemont Circle
Gaithersburg, Maryland 20877-4121
301-977-3698
301-977-9589 FAX
www.nebb.org
PROCEDURAL STANDARD FOR
FUME HOOD PERFORMANCE TESTING
©Copyright NEBB, 2009
FIRST EDITION – MARCH 2009
NEBB DEVELOPS AND SPECIFIES STANDARDS FOR TESTING OF FUME HOOD
PERFORMANCE. PERFORMANCE OF THESE SERVICES ONLY BY PERSONS THAT ARE
CERTIFIED OR QUALIFIED FOR ENGAGING IN THIS SPECIALTY IS ONE SUCH
STANDARD. NEBB SOLICITS INQUIRY BY ANY AND ALL PERSONS SEEKING SUCH
APPROVALS. FOR MORE INFORMATION, GO TO WWW.NEBB.ORG.
This book may not be reproduced in any form without written permission of the
copyright owner.
These Procedural Standards were developed using reliable engineering principles and
research plus consultation with, and information obtained from, manufacturers, users,
testing laboratories and others having specialized experience. They are subject to
revision as further experience and investigation may show is necessary or desirable.
Fume Hood Testing, which complies with these Procedural Standards, will not necessarily
be acceptable, if when examined and tested, it is found to have other features that impair
the result intended by these standards. The National Environmental Balancing Bureau
assumes no responsibility and has no liability for the application of the principles or
techniques contained in these Procedural Standards. Authorities considering adoption of
these Procedural Standards should review all Federal, State, local and contract
regulations applicable to the specific installation.
II
FOREWORD
The purpose of the NEBB Procedural Standards for Fume Hood Performance Testing is to establish a
uniform and systematic set of criteria for the performance testing of fume hoods.
This publication is the first edition of the Procedural Standard. Similar to the other NEBB disciplines,
the Procedural Standard serves as the anchor for the program. Fume hoods and other safety control
environments, such as bio-safety cabinets, offer a distinct set of challenges to the firms and
individuals testing the field performance of these specialized, containment enclosures. The American
Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) has developed an
ANSI/ASHRAE Standard 110 Method of Testing Performance of Laboratory Fume Hoods. Another
standard is ANSI/AIHA Standard Z9.5 Laboratory Ventilation. These publications define the testing
procedures to be used when testing fume hoods and are well recognized and respected in this area of
expertise. The NEBB discipline builds on these standards and complements them by providing a
program that combines their testing requirements with a complete package for firm certification.
The NEBB Procedural Standard and the NEBB Fume Hood Testing program define the requirements
for firm certification, for Certified Professional educational and experience requirements, for reporting
consistencies, and for instrumentation requirements.
This Procedural Standard is similar to other NEBB Procedural Standards in that it is divided into two
distinct Parts: Standards and Procedures. These FHT procedural standards have been developed
using language defined by “Shall, Should, and May” as it relates to the standards and procedures
described in this manual. It is important to note these particular words throughout this manual and
how they pertain to the NEBB standards and procedures.
These standards and procedures are intended as the minimum NEBB requirements that a NEBB
Certified FHT Firm shall follow when performing fume hood testing and reporting the results. Contract
documents may supercede the NEBB requirements. These Procedural Standards have been
carefully compiled and reviewed by the NEBB Technical Committees.
Part 1 STANDARDS
Part 1, STANDARDS, covers the requirements for Quality Control and Compliance, Instrumentation
Requirements, and FHT Reports. The report requirements allow the NEBB Certified Firm more
flexibility in designing their reports by prescribing sets of information that "Shall, Should and/or May"
be required to complete an FHT Report.
Part 2 PROCEDURES
Part 2, PROCEDURES, covers required testing procedures to be followed when using ASHRAE 110
and ANSI Z9.5. Part 2 also addresses criteria and testing procedures other than those dictated by
those referenced standards. This Procedural Standard allows that flexibility.
APPENDICES
The Appendices includes a suggested NEBB FHT specification, test illustrations, ejector
specifications references and engineering formulas.
This Edition of the FHT Procedural Standards, when used by NEBB Certified FHT Firms, will assure
the building owner of standard, accurate reporting of fume hood performance.
Andrew P. Nolfo, P.E.
NEBB Technical Director
III
FUME HOOD COMMITTEE MEMBERS
AND OTHER CONTRIBUTORS FOR CURRENT EDITION
Current FHT Committee:
Bohdan (Don) Fedyk, Chairman
Buffalo, New York
Michael J. Kelly
Bethlehem, Pennsylvania
Michael L. Lancette
St. Paul Park, Minnesota
Thomas R. McKeen, PE
San Antonio, Texas
David G. McFarlane
Grand Forks, North Dakota
David Muggah
Sydney, Nova Scotia, Canada
W. David Bevirt, PE
Tucson, Arizona
Andrew P. Nolfo, PE
Phoenix, Arizona
Additional Contributors to the First Edition:
Michael P. Dolim
Gaithersburg, Maryland
Randall Silva
San Jose, California
IV
Michael A. Wieder
Bethlehem, Pennsylvania
TABLE OF CONTENTS
PAGE
Foreword
NEBB Fume Hood Testing Committee
Table of Contents
III
IV
V
PART 1 – STANDARDS
SECTION 1 Definitions
1
SECTION 2 NEBB Program, Quality Control and Compliance
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2.1
2.2
2.3
2.4
NEBB Programs
2.1.1 NEBB Disciplines
2.1.2 Certification of Firms
2.1.3 Certification of Professionals
2.1.4 Recertification Requirements
Quality Assurance Program – Conformance Certification
2.2.1 Program Advantages
2.2.2 NEBB Quality Assurance Program Certificate
Quality Control and Compliance
2.3.1 FHT Work Compliance
FHT Professional Responsibilities
2.4.1 Execution of FHT Procedures
2.4.2 Technician Training
2.4.3 FHT Procedures Training
2.4.4 Instrument Use and Maintenance
2.4.5 Coordination / Supervision
2.4.6 Project Communication
2.4.7 Work Completion
2.4.8 Compilation and Submission of Final FHT Reports
SECTION 3 Responsibilities
3.1
3.2
Introduction
Design and Construction Team Responsibilities
3.2.1 Design Professional’s Responsibilities
3.2.2 Construction Team Responsibilities
3.2.3 NEBB Certified FHT Firm Responsibilities
SECTION 4 Standards for Instrumentation and Calibration
4.1
4.2
4.3
Minimum Instrumentation
Range and Accuracy
Calibration
Table 4-1 NEBB Minimum FHT Instrumentation Requirements
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NEBB FHT PROCEDURAL STANDARDS
TABLE OF CONTENTS
PAGE
SECTION 5 Standards for Reports and Forms
5.1
5.2
Reports
Required Forms
5.2.1 Report Title
5.2.2 Report Certification
5.2.3 Table of Contents
5.2.4 Report Summary / Remarks
5.2.5 All Report Pages
5.2.6 Instrument Calibration
5.2.7 Abbreviations
5.2.8 Airflow Velocity Test Report Data – Constant
Volume Systems
5.2.9 Airflow Velocity Test Report Data – VAV Systems
5.2.10 Airflow Visualization Test Report Data – Local Challenge
5.2.11 Airflow Visualization Test Report Data – Large Volume
Challenge
5.2.12 Tracer Gas Containment Test Report Data – Static Mode
5.2.13 Tracer Gas Containment Test Report Data – Sash Movement
Effect
5.2.14 Tracer Gas Containment Test Report Data – Perimeter Scan
5.2.15 Other Fume Hood Performance Test Report Data
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PART 2 - PROCEDURES
SECTION 6 Laboratory and Cleanroom Safety
6.1 Introduction
6.2 Designing A Program Policy Health and Safety
6.2.1 Designing a Program Policy
6.2.2 Designing a Training Program
6.2.3 Essentials of the Health and Safety Program
6.3 Responsibilities
6.3.1 Individual Health and Safety Responsibilities
6.4 Elements Of The Program
6.4.1 Project Specific Items
6.4.2 Health and Safety Program Implementation
SECTION 7 Laboratory and Cleanroom Protocol
7.1 Introduction
7.2 Laboratory And Cleanroom Procedures
7.2.1 Gowning Procedures
7.2.2 Equipment Entrance Procedures
7.2.3 Laboratory / Cleanroom Conduct
Section 8 Overview of Testing Requirements
8.1 Introduction
8.2 Test Setup Procedures
VI
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NEBB FHT PROCEDURAL STANDARDS
TABLE OF CONTENTS
PAGE
8.2.1 Fume Hood Types
8.2.2 Fume Hood Sash Configurations
8.2.3 Test Setups
8.3 ANSI/ASHRAE Standard 110
8.4 ANSI/AIHA Standard Z9.5
8.5 Preliminary Test Procedures
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SECTION 9 Airflow Velocity Test Procedures
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9.1 Introduction
9.2 Airflow Velocity Tests – Constant Air Volume (CAV) Fume Hood
9.2.1 Instruments and Equipment
9.2.2 Test Procedures (Average Airflow Face Velocity)
9.2.3 Acceptance
9.2.4 Reporting
9.3 Airflow Velocity Tests – Variable Air Volume (VAV) Fume Hood
9.3.1 Instruments and Equipment
9.3.2 Test Procedures (Average Airflow Face Velocity)
9.3.3 Test Procedures (Response Time)
9.3.4 Acceptance
9.3.5 Reporting
SECTION 10 Airflow Visualization Test Procedures
10.1
10.2
10.3
Introduction
Airflow Visualization Tests – Local Challenge
10.2.1 Instruments and Equipment
10.2.2 Test Procedures
10.2.3 Acceptance
10.2.4 Reporting
Airflow Visualization Tests – Large Volume Challenge
10.3.1 Instruments and Equipment
10.3.2 Test Procedures
10.3.3 Acceptance
10.3.4 Reporting
SECTION 11 Tracer Gas Containment Test Procedures
11.1
11.2
Introduction
Tracer Gas Containment Tests
11.2.1 Instruments and Equipment
11.2.2 Test Procedures (Static Mode)
11.2.3 Acceptance (Static Mode)
11.2.4 Reporting (Static Mode)
11.2.5 Test Procedures (Sash Movement Effect)
11.2.6 Acceptance (Sash Movement Effect)
11.2.7 Reporting (Sash Movement Effect)
11.2.8 Test Procedures (Perimeter Scan)
11.2.9 Acceptance (Perimeter Scan)
11.2.10 Reporting (Perimeter Scan)
VII
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NEBB FHT PROCEDURAL STANDARDS
TABLE OF CONTENTS
PAGE
SECTION 12 Optional Tests and Procedures
12.1
12.2
12.3
Introduction
Other Tests and Procedures
Supplementary Tests and Procedures
12.3.1 Room Airflow Velocity Tests
12.3.2 Temperature/Humidity Uniformity Tests
12.3.3 Sound and Vibration Level Tests
12.3.4 Cross Draft Condition Tests
12.3.5 Other Tests
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APPENDICES
APPENDIX A
APPENDIX B
APPENDIX C
APPENDIX D
APPENDIX E
Sample FHT Specification
Example Test Illustrations
Ejector System Specifications
References and Referenced Publications
Engineering Formula and Examples
VIII
I
XXI
XXV
XXIII
XXXV
PART 1 - STANDARDS
SECTION 1 DEFINITIONS
These procedural standards have been developed using language defined by “Shall, Should,
and May" as it relates to the standards and procedures described in this publication. It is
important to note these particular words throughout this publication and how they pertain to
NEBB standards and procedures.
Acceptance Criteria: The value or range of values which is compared to the measured value that will
determine if the results of the test pass or fail.
Accuracy: The capability of an instrument to indicate the true value of a measured quantity.
AHJ: The local governing Authority Having Jurisdiction over the installation.
Air Supply Fixtures: Devices or openings through which air flows into the laboratory room. For the
purpose of this standard all accessories, connecting duct adapters, or other mounting airways shall be
considered part of the supply fixture and reported as a unit or an assembly. Some specific supply
fixtures are defined as follows:
grille: a louvered or perforated face over an opening.
register: a combination grille and damper assembly.
diffuser: an outlet designed to mix supply air and room air and to distribute it in varying directions.
perforated ceiling: a ceiling with perforated panels used to distribute the air uniformly throughout
the ceiling or a portion of the ceiling. Filter pads may be used to achieve a similar result.
Auxiliary Air: Unconditioned or partially conditioned supply or supplemental air delivered to a
laboratory at the laboratory fume hood to reduce room air consumption.
Calibrate: The act of comparing an instrument of unknown accuracy with a standard of known
accuracy to detect, correlate, report, or eliminate by adjustment any variation in the accuracy of the
tested instrument.
Control Level: The average measured concentration of tracer gas, in parts of tracer gas per million
parts of air by volume (ppm), that is not exceeded at the hood face with a 4.0 Lpm release rate.
Deficiency: Any circumstance or operation that affects the measurement results as compared to the
design criteria required by the contract documents.
Design Sash Opening: The position of the sash at which the design team assumes that the fume
hood will be operating.
Face Velocity: The average velocity of air moving perpendicular to the hood face, usually expressed
in feet per minute (fpm) or meters per second (m/s).
1
NEBB FHT PROCEDURAL STANDARDS
SECTION 1
DEFINITIONS
Fume Hood (sometimes referred to as a laboratory hood): A box-like structure enclosing a source
of potential air contamination, normally with one open or partially open side, into which air is moved
for the purpose of containing and exhausting air contaminants. A fume hood is generally used for
bench-scale laboratory operations but does not necessarily involve the use of a bench or table.
Fume Hood System: An arrangement consisting of a fume hood, its adjacent room environment,
and the air exhaust equipment, such as blowers and ductwork, required to make the hood operable.
Function: For the purposes of this NEBB Standard, function refers to the specific type of data
measurement specified in Section 4, Standards for Instrumentation and Calibration.
High Value of Range: The maximum response time divided by the average response time of the
VAV Response Time Test. Value is expressed as a percentage.
Hood Face: The plane of minimum area at the front portion of a laboratory fume hood through which
air enters when the sash(es) is (are) fully opened, usually in the same plane as the sash for a hood
with a vertical sash. For a hood with horizontal sash(es) or a combination sash, the hood face is
usually the plane passing through the midpoint between the inner and outer sashes.
Lazy Airflow: Airflow within the hood is described as lazy when smoke remains on the work surface
without smoothly flowing to the back baffle.
LPM: Liters per minutes.
Low Value of Range: The minimum response time divided by the average response time of the VAV
Response Time Test. Value is expressed as a percentage.
May: Used to indicate a course of action that is permissible as determined by the NEBB Certified
FHT Firm.
Maximum Sash Opening: The position of the sash at which the fume hood has the largest opening.
N/A: Not Available, Not Applicable, or Not Accessible. The simple notation “N/A” without definition is
not allowed.
NEBB Certified FHT Firm: A NEBB Certified FHT Firm is a firm that has met and maintains all the
requirements of the National Environmental Balancing Bureau for firm certification in Fume Hood
Performance Testing and is currently certified by NEBB. A NEBB Certified FHT Firm shall employ at
least one NEBB Certified FHT Professional in a full time management position.
NEBB Certified FHT Report: The data presented in a NEBB Certified FHT Report accurately
represents system measurements obtained in accordance with the current edition of the NEBB
Procedural Standards for Fume Hood Performance Testing. A NEBB Certified FHT Report does not
necessarily guarantee that systems measured conform to the design requirements or stated
guidelines. The report is an accurate representation of the measured results only.
NEBB Certified FHT Professional: A NEBB Certified FHT Professional is a full time employee of
the firm in a management position who has successfully passed the professional level written and
practical qualification examinations and maintains the Certified FHT Professional recertification
requirements of NEBB.
2
NEBB FHT PROCEDURAL STANDARDS
SECTION 1
DEFINITIONS
Operating Sash Opening: The position of the sash at which the fume hood user places the sash
while working at the face of the fume hood. The operating sash opening should take into
consideration all of the procedures to be conducted in the fume hood. There may be more than one
operating sash opening.
Performance Rating: Rating definition of the Static Mode Test portion of the Tracer Gas Tests. It is
comprised of a series of letters and numbers consisting of the letters AM, AI, or AU, and three-digit
number:
AM yyy
AI yyy
AU yyy
Where:
AM indicates the test setup is "As Manufactured,"
AI indicates the test setup is "As Installed,"
AU indicates the test setup is "As Used,"
yyy indicates the control level of tracer gas established by the test in ppm.
As an example: A test rating of AU 0.500 would indicate that the fume hood controls the
leakage into the laboratory to 0.500 ppm at the mannequin's sensing point with a tracer gas
release rate of 4.0 Lpm.
Positional Sash Movement Effect Control Level: The maximum 45-second moving average of the
tracer gas concentration observed during a series of sash movement tests at one ejector and
mannequin position.
Positional Control Level: The average tracer gas concentration at a position during a test.
Precision: The ability of an instrument to produce repeatable readings of the same quantity under
the same conditions. The precision of an instrument refers to its ability to produce a tightly grouped
set of values around the mean value of the measured quantity.
PPM: Parts per million.
Procedure: The approach to and execution of a sequence of work operations to yield a repeatable
and defined result.
Range: The upper and lower limits of an instrument’s ability to measure the value of a quantity for
which the instrument is calibrated.
Relative Range: The range from the Low Value of Range to the High Value of Range. Reported as
percentages.
Release Rate: The rate of release, in actual liters (litres) per minute (Lpm), of tracer gas during a
hood test.
Repeatability: The difference from the Low Value of Range to the High Value of Range. Reported as
a percentage.
Resolution: The smallest change in a measured variable that an instrument can detect.
3
NEBB FHT PROCEDURAL STANDARDS
SECTION 1
DEFINITIONS
Reverse Flow: Airflow within the hood when smoke released in the hood moves forward toward the
front of the hood. This term does not apply to the forward motion of the roll inside the hood that
occurs in the upper cavity of the hood above the hood opening or to the cyclonic motion that occurs
behind a closed horizontal sash.
Roll: The rotation of air, commonly referred to as vortex, in the upper cavity of the hood. The roll is
induced by the momentum of the air entering the hood through the hood opening.
Sash Movement Effect: The maximum of the positional sash movement effects for all the positions
tested on a particular hood.
Sash Movement Effect Performance Rating: Rating definition of the Sash Movement Effect Test
portion of the Tracer Gas Tests. It is comprised of a series of letters and numbers consisting of the
letters SME-AM, SME-AI, or SME-AU, and three-digit number:
SME-AM yyy
SME-A I yyy
SME-AU yyy
Where:
SME means "sash movement effect,"
AM indicates the test setup was "As Manufactured,"
AI indicates the test setup was "As Installed,"
AU indicates the test setup was "As Used,"
yyy equals the sash movement effect, in ppm.
For example: A test rating of SME-AI 10.0, indicates the fume hood was tested in the “AsInstalled” test setup and that the maximum 45-second rolling average concentration of tracer
gas measured during a sash movement test was 10.0 ppm with a tracer gas release rate of
4.0 Lpm .
Shall: The term is used to indicate mandatory requirements that must be followed in order for the
project to become a NEBB certified project. Work must conform to these standards and procedures
and no deviation is permitted. Note: In the event unique circumstances prevent a required action from
being fulfilled, a notation shall be included in the FHT report explaining the reason that the
requirement was not completed. For example, such notation could be one of the following:
Not Available, Not Applicable, or Not Accessible. The simple notation “N/A” without definition is not
allowed.
Should: The term is used to indicate that a certain course of action is preferred but not necessarily
required.
Specified Rating: The hood performance rating as specified, proposed, or guaranteed either in the
purchase of the hood or in the design and construction of the laboratory, or both.
Standard: A required qualification, action, or result for FHT work.
Standard Operating Procedure: An internal policy prepared by the each FHT firm and / or prepared
by the Owner/Buyer. Procedures are written to provide guidance, direction, and step-by-step details
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NEBB FHT PROCEDURAL STANDARDS
SECTION 1
DEFINITIONS
relating to issues such as safety, testing protocols, acceptance criteria, etc. NEBB FHT Firm SOP’s
shall be utilized in an absence of SOP’s prepared by the Owner.
Test Sash Opening: The position or positions of the sash at which the fume hood is tested.
Test Setup (Test Setup Mode): Defines the condition of the fume hood being tested. There are
three distinct conditions that the fume hood may be tested:
As-Manufactured (AM): With this test setup, the fume hood is tested at the manufacturer’s
facility or under conditions that would replicate those conditions. The hood and work surface
shall be void of all process equipment, apparatus and chemicals.
As-Installed (AI): With this test setup, the actual fume hood is tested in its installed, operating
condition. All supply, exhaust and return air systems are installed, operable and under control.
The hood and work surface shall be void of all process equipment, apparatus and chemicals.
As-Used (AU): This test setup is the same as the As-Installed setup except the hood is being
utilized for actual process work. Experiment equipment, chemicals and processes are being
carried out inside the hood while the fume hood performance testing is being performed. This
means that all normal operating equipment within the hood shall be activated and operational
including items such as all heat and vapor producing appliances, physical obstructions, etc.
Testing: The use of specialized and calibrated instruments to measure fluid quantities, temperatures,
pressures, rotational speeds, electrical characteristics, velocities, and sound and vibration levels,
Testing, Adjusting, and Balancing (TAB): A systematic process or service applied to heating,
ventilating and air-conditioning (HVAC) systems and other environmental systems to achieve and
document air and hydronic flow rates. The standards and procedures for providing these services are
addressed in the current edition of the NEBB “PROCEDURAL STANDARDS FOR THE TESTING,
ADJUSTING AND BALANCING OF ENVIRONMENTAL SYSTEMS.”
VAV Speed of Response: The time, measured from the first movement of the sash, for the VAV
system to restore the slot velocity or airflow to 90 percent of the average steady-state value.
VAV Time to Steady State: The time, measured from the first movement of the sash, for the VAV
system to restore and maintain the average slot velocity of airflow between 90 and 110 percent of the
average steady-state value.
Work Surface: The surface that the fume hood sets on.
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NEBB FHT PROCEDURAL STANDARDS
6
SECTION 1
DEFINITIONS
SECTION 2 NEBB PROGRAM,
QUALITY CONTROL AND
COMPLIANCE
2.1 NEBB PROGRAMS
The National Environmental Balancing Bureau (NEBB) is a not-for-profit organization founded in 1971
to:
a) develop standards, procedures and programs for the performance of testing, balancing and
commissioning of building systems,
b) promote advancement of the industry through technical training and development,
c) operate programs to certify firms and qualify individuals who meet and maintain NEBB
standards with integrity.
Additional information on NEBB Programs is available at www.nebb.org.
2.1.1 NEBB DISCIPLINES
NEBB establishes and maintains standards, procedures, and specifications for work in its various
disciplines, which include:
a)
b)
c)
d)
e)
f)
g)
Testing-Adjusting-Balancing (TAB) -- Air and Hydronic Systems
Sound (S) Measurement
Vibration (V) Measurement
Cleanroom Performance Testing (CPT)
Building Systems Commissioning (BSC)
Fume Hood Performance Testing (FHT)
Retro-Commissioning (RCx-EB)
Each discipline is anchored by a NEBB Procedural Standards manual that provides guidelines for
work to be performed. NEBB also has created technical manuals, training materials and programs,
and seminars to enhance and support each discipline.
2.1.2 CERTIFICATION OF FIRMS
NEBB certifies firms that meet certain criteria, ensuring strict conformance to its high standards and
procedures. Among other requirements, NEBB Certified FHT Firms must document a record of
responsible performance, own a complete set of instruments and equipment required for the
sophisticated techniques and procedures necessary to take and report fume hood testing
measurements, and have a NEBB Certified FHT Professional as a full-time employee.
2.1.3 CERTIFICATION OF PROFESSIONALS
NEBB also establishes professional qualifications for the supervision and performance of work in its
various disciplines. NEBB Certified FHT Professionals must have extensive experience, and they
must pass appropriate, college-level written examinations and demonstrate certain practical working
knowledge and proficiency in the use of instruments required for the various disciplines.
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NEBB FHT PROCEDURAL STANDARDS
SECTION 2
NEBB PROGRAM, QUALITY CONTROL
AND COMPLIANCE
2.1.4 RECERTIFICATION REQUIREMENTS
Through the recertification procedures, the firm must verify that its NEBB Certified FHT Professional is
still on staff and that it continues to own a complete set of instruments that are in current calibration.
In addition, the firm's NEBB Certified FHT Professional renews his or her certification annually.
Among other requirements, the Certified Professional must keep abreast of developments in their
discipline by successfully completing continuing education requirements annually.
2.2 QUALITY ASSURANCE PROGRAM - CONFORMANCE CERTIFICATION
The credibility of NEBB is built by maintaining integrity through high standards, quality programs, and
demonstrated capabilities of its certified firms. As further assurance, NEBB offers a Quality
Assurance Program to guarantee that the work will be accomplished in accordance with its standards.
NEBB’s Quality Assurance Program applies to each project. It assures that the NEBB Certified Firm
will perform specified services in conformity with the current applicable NEBB Procedural Standards.
2.2.1 PROGRAM ADVANTAGES
The NEBB Quality Assurance Program affords building owners, architects, engineers and other
agents a reliable basis for specifying work within the various disciplines of NEBB. The program
promotes proper execution of projects by ensuring compliance with NEBB standards and procedures.
2.2.2 NEBB QUALITY ASSURANCE PROGRAM CERTIFICATE
The NEBB Quality Assurance Program Conformance Certificate is not required, but is available for
any project.
2.3 QUALITY CONTROL AND COMPLIANCE
Building owners are entitled to a professional service by every NEBB Certified Firm on every project,
whether the job is NEBB-specified or not. It is the responsibility of the NEBB Certified FHT Firm and
its NEBB Certified FHT Professional to establish and maintain procedures and practices that will
assure a consistent pattern of high quality work on all projects. This point cannot be overemphasized.
2.3.1 FHT WORK COMPLIANCE
Either the design professional or the owner / buyer should adequately define the scope of the fume
hood performance testing services. Many of today’s contract documents do not define the actual
scope of services to be performed on the project. Contract documents may reference desired
procedures and may include statements such as "…the work will be performed in accordance to
NEBB Standards…" or, the contract documents may refer to NEBB and that fume hood performance
testing work “…shall be done in accordance with the reference standard…” or, merely allude to the
NEBB organization, ASHRAE, or ANSI, or owner / buyer defined reference standards and make
reference to fume hood performance testing work.
When contract documents do not clearly identify the exact scope of fume hood performance testing
services, the NEBB Certified FHT Professional shall make every attempt to have the design
professional, or the owner / buyer, dictate the actual scope of work.
Regardless of what is the scope of work, in all cases the process by which the data is acquired shall
conform to the current edition of the NEBB Procedural Standards for Fume Hood Performance
Testing.
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NEBB FHT PROCEDURAL STANDARDS
SECTION 2
NEBB PROGRAM, QUALITY CONTROL
AND COMPLIANCE
References to desired procedures may include statements such as "the work will be performed in
accordance to NEBB Standards." When specifications indicate that the fume hood testing work shall
be performed in accordance with NEBB standards, the FHT procedures will conform to the current
edition of the NEBB Procedural Standards for Fume Hood Performance Testing and must be
performed by a NEBB certified firm.
The scope of work shall be performed as specified in the contract documents or as agreed to between
the owner / buyer and the NEBB Certified FHT Firm. Each relevant or applicable item as identified in
the scope of work shall be performed and recorded in NEBB FHT Final Report. Data presented in the
NEBB FHT Final Report shall provide an accurate record of the system tests, measurements, data
and information.
a. The NEBB Certified FHT Firm and the NEBB Certified FHT Professional are allowed to sign
and stamp a fume hood testing report as a NEBB Certified FHT Report only when the
procedures and requirements as identified in these Procedural Standards have been followed.
b. A NEBB Certified FHT Report should consist of all three primary fume hood tests (Airflow
Velocity Tests, Airflow Visualizations Tests, and Tracer Gas Containment Tests), but may
consist of any single primary test or any combination of primary tests as described in these
Procedural Standards. To qualify as a NEBB Certified Report, the procedures and
requirements for each primary test included in the report SHALL adhere to the requirements of
these Procedural Standards.
c. For some projects, the scope of work of the fume hood testing may require testing
requirements, procedures, reporting requirements, etc. that are different from those required
by this Procedural Standard. The scope of work may require testing to another industry
standard or an owner / buyer defined set of testing requirements. For these projects, the
Certified FHT Final Report MAY be signed and stamped as a NEBB Certified FHT Report only
if the procedural variances are clearly delineated in the project scope of work and identified on
the report Certification Page. See Section 5.2.2.
d. Any project that does not comply with the minimum SHALL requirements of this standard and
does not clearly identify the specific procedural variances required by the fume hood testing
contract on the certification page SHALL NOT be signed and stamped as a NEBB certified
FHT report. All references to NEBB, including NEBB logos, stamps, certifications, etc. SHALL
be removed from the report.
2.4 FHT PROFESSIONAL RESPONSIBILITIES
It is the responsibility of the NEBB Certified FHT Professional to control the quality of the fume hood
performance testing work. This means that the NEBB Certified FHT Firm, through its NEBB Certified
FHT Professional, shall satisfy the contract obligations set forth in the drawings and applicable
specifications.
2.4.1 EXECUTION OF FUME HOOD TESTING PROCEDURES
The NEBB Certified FHT Professional shall have project responsibility, which includes authority to
represent the NEBB Certified FHT Firm. Examples of project responsibility may include labor
decisions, negotiating change orders, committing to contract interpretations and implementing
changes in job schedules.
9
NEBB FHT PROCEDURAL STANDARDS
SECTION 2
NEBB PROGRAM, QUALITY CONTROL
AND COMPLIANCE
The NEBB Certified FHT Professional has the responsibility to assure that the measurements of the
fume hood performance testing have been performed in accordance with these Procedural Standards
and the contract documents to assure the accuracy of all data included in the final report. Factors
such as instrument use, coordination / supervision, work instructions, and project communication play
a critical role in achieving this requirement.
2.4.2 TECHNICIAN TRAINING
The NEBB Certified FHT Professional has a responsibility to assure that technicians performing the
work are properly trained and possess sufficient skills. Areas that should be stressed are fume hood
performance testing procedures, instrument use and maintenance, safety procedures, coordination
and supervision, and project communication.
2.4.3 FHT PROCEDURES TRAINING
NEBB Certified FHT Professionals must be prepared to completely measure and record data in the
manner specified. It is mandatory that NEBB Certified FHT Professionals possess the ability to
perform the specific tasks and procedures required for each project. An understanding of building
system fundamentals and operating characteristics is important, and technicians should possess
rudimentary knowledge of all related systems and procedural considerations. This may require
periodic training to promote knowledge and skill development as well as to facilitate the transfer of
knowledge and basic skills in the use of new technology.
2.4.4 INSTRUMENT USE AND MAINTENANCE
NEBB Certified FHT Professionals shall possess knowledge and skill in the proper use and care of
instruments required to perform the work. This shall include a thorough understanding of the
operating principles and use of fume hood equipment and instruments. Considerations for the
delicate nature of many of the instruments typically used, as well as the adverse effects of dirt, shock,
jarring movements and exceeding rated capacities, shall be addressed along with the proper methods
for storing and transporting the instruments.
2.4.5 COORDINATION / SUPERVISION
The NEBB Certified FHT Professional shall be responsible for directing technicians in performing the
work. Instructions may delineate items such as the scope of work, location, type and quantity of
measurements, etc. so that field personnel may know exactly what to do and what is required of them.
2.4.6 PROJECT COMMUNICATION
The NEBB Certified FHT Professional shall report on progress made toward work completion, when
required, as well as report and address problems if encountered. When a problem exists, the NEBB
Certified FHT Professional should notify the appropriate project personnel.
2.4.7 WORK COMPLETION
The NEBB Certified FHT Professional shall determine when the fume hood performance testing work
has been completed, and when to submit the report. Generally, the specified fume hood performance
testing field work is complete when:
a) All specified fume hood performance testing is completed;
or
b) Reasonable efforts within the extent of testing for fume hoods have been performed in an effort
10
NEBB FHT PROCEDURAL STANDARDS
SECTION 2
NEBB PROGRAM, QUALITY CONTROL
AND COMPLIANCE
to complete all required measurements. The NEBB Certified FHT Professional shall notify the
appropriate project personnel of any significant system deficiencies preventing fume hood
performance testing from being performed before the final report is submitted.
2.4.8 COMPILATION AND SUBMISSION OF FINAL FHT REPORTS
Reports shall include information and data to provide an accurate quantitative and qualitative record
of system measurements and information. Reports also shall include notes and comments, as
appropriate, to provide the reviewer with additional details related to the test procedure, system
operation and results. Reports shall meet the criteria listed in Section 5.
The certification page shall bear the stamp of the NEBB Certified FHT Professional. The stamp on
the certification page shall be signed as evidence that the NEBB Certified FHT Professional has
personally reviewed and accepted the report. Signature stamps are specifically prohibited.
11
NEBB FHT PROCEDURAL STANDARDS
SECTION 2
NEBB PROGRAM, QUALITY CONTROL
AND COMPLIANCE
12
SECTION 3 RESPONSIBILITIES
3.1 INTRODUCTION
Many approaches can be taken to deliver successful performance testing of fume hoods on a project.
In order to maximize value and benefits from fume hood performance testing, it is important to
understand that the design professionals and other construction team members have responsibilities
that will affect the outcome of the fume hood testing process.
The following outline represents recommended practices that may take place on a conventional
design/bid/buy/construct delivery project or on a direct procurement project between the Owner/Buyer
and the NEBB Certified FHT Firm. While other delivery approaches exist, the overall concept of the
delineation of responsibilities remains. The Owner/Buyer must be the responsible party that dictates
the recommended following procedures.
3.2 DESIGN AND CONSTRUCTION TEAM RESPONSIBILITIES
3.2.1 DESIGN PROFESSIONAL’S RESPONSIBILITIES
It is recommended that the contract documents must:
a) Specify the equipment, systems and scope of testing services to be performed for the fume
hoods on the project. NEBB standards and procedures define industry best practices to
perform the measurements.
b) Define who retains the services of the NEBB Certified FHT Firm and require that the NEBB
Certified FHT Firm be retained early in the construction process.
c) Clearly define on the contract documents all fume hood performance testing requirements
including setup mode, design sash opening, acceptance criteria and reporting requirements.
d) Clearly identify on the contract documents all locations where fume hood performance testing
is to be performed.
e) Specify that the building, mechanical, electrical and all associated work is to be completed
prior to performing fume hood performance testing.
f)
Specify that all building, mechanical, electrical, and other systems are completely operational,
under control and performing according to the design intent prior to performing fume hood
performance testing. This would include that all building automation / controls are installed,
operational, calibrated and functioning properly and that the TAB work is completed. Fume
hood performance testing performed prior to completion of these activities should be avoided.
Actual final measurements may differ from measurements taken prior to the completion of the
work.
g) Provide adequate access to all equipment and components required by the fume hood
performance testing process.
13
NEBB FHT PROCEDURAL STANDARDS
SECTION 3
RESPONSIBILITIES
3.2.2 CONSTRUCTION TEAM RESPONSIBILITIES
It is recommended that the construction team must:
a) Provide the NEBB Certified FHT Firm with a conformed set of contract documents (drawings,
specifications, and approved submittals), including all current approved change orders and
contract modifications.
b) Develop a project schedule, with the input of the NEBB Certified FHT Firm that coordinates the
work of other disciplines and provides adequate time in the construction process to allow
successful completion of the fume hood performance testing work.
c) Notify the NEBB Certified FHT Firm of all schedule changes.
d) Ensure that the building enclosure is complete, including but not limited to, all structural
components, windows and doors installed, door hardware complete, floor and ceilings
complete. Ensure that the building enclosure and components are complete and operational
such that the performance of the fume hoods would not be adversely affected.
e) Ensure that all necessary building systems are complete and are operating in a safe manner.
f)
Complete the installation of permanent electrical power systems serving the building systems.
Such electrical systems shall be properly installed in accordance with all applicable codes to
ensure the safety of all construction personnel.
g) Perform start up of all building systems in accordance with manufacturers' recommendations.
h) Complete the installation, programming (including design parameters and graphics),
calibration and startup of all building control systems. Verify that the building control system
provider has commissioned and documented all building control work.
i)
Complete all TAB related work. A copy of the completed TAB Report shall be furnished to the
NEBB FHT Firm. If this is a recertification project, provide the NEBB FHT Firm with a copy of
the most recent TAB Report or the most recent Fume Hood Performance Test Report.
3.2.3 NEBB CERTIFIED FHT FIRM RESPONSIBILITIES
The NEBB Certified FHT Firm SHALL:
a) Follow the current NEBB standards and procedures when performing the fume hood
performance testing.
b) Communicate on a regular basis, through proper channels, items pertaining to design,
installation or function that prevent the NEBB Certified FHT Firm from achieving completion of
the FHT work in accordance with the current edition of the NEBB Procedural Standards for
Fume Hood Performance Testing.
c) Perform the required fume hood performance tests.
d) Publish a NEBB Certified FHT Report of final conditions that accurately reflect the results of
the fume hood performance testing.
14
SECTION 4 STANDARDS FOR
EQUIPMENT,
INSTRUMENTATION AND
CALIBRATION
4.1 MINIMUM INSTRUMENTATION
A NEBB Certified FHT Firm will use a variety of instrumentation to perform the specified fume hood
performance tests on a project. It is the responsibility of the NEBB Certified FHT Firm to provide
appropriate instrumentation that meets the minimum requirements for use on a project.
Instrumentation used on a NEBB project shall be in proper operating condition and shall be applied in
accordance with the manufacturer’s recommendations. Table 4-1 lists the minimum instrumentation
specifications that a NEBB Certified FHT firm shall utilize in all fume hood performance testing. The
NEBB Certified FHT Firm shall own all of the required instrumentation and equipment as identified in
Table 4-1.
4.2 RANGE AND ACCURACY
The accuracy and range as reported by the instrument manufacturer shall be verified by a testing
laboratory traceable to the National Institute of Standards and Technology or equivalent institute in
countries other than the United States. Calibration requirements for each function are specified and
shall be met. Some instruments and accessories may not require calibration. However, if a
"mechanical / electrical" device is substituted or employed in place of these types of instruments, the
indicated calibration requirements noted shall apply. Instrumentation with multiple capabilities shall
be accepted for more than one function when submitting documentation for a firm’s certification,
providing that each separate function meets NEBB requirements.
4.3 Calibration
Annual Calibration – ALL fume hood performance testing instrumentation SHALL be maintained with
a current annual calibration certificate, traceable to the National Institute of Standards and Technology
(NIST), or equivalent organizations in other countries, or manufacturers’ specifications, whichever is
more stringent.
Firms with multiple sets of instrumentation SHALL calibrate all instrumentation used by the firm on
FHT projects in accordance with Table 4-1 as a minimum requirement for NEBB certification.
15
NEBB FHT PROCEDURAL STANDARDS
SECTION 4
STANDARDS FOR EQUIPMENT,
INSTRUMENTATION AND CALIBRATION
TABLE 4-1 NEBB MINIMUM FHT INSTRUMENTATION REQUIREMENTS
Test
Airflow
Velocity Tests
– Average
Face Velocity
(CAV & VAV)
(Sections 9.2 &
9.3)
Instruments &
Equipment
Linear Measuring Device
Description
Equipment Stand
Stationary stand (ring stand) that will allow the
airflow face velocity measuring device to be
secured.
Not Required
Airflow Velocity Instrument
(One of the following Shall
be provided)
A digital manometer and either an array-type
grid or airfoil-type probe. The manometer shall
have the following characteristics:
12 Months
(Meter only)
Minimum 12’ (3.6 m) tape measure capable of
reading 1/16” (1.0 mm) increments
Calibration
Interval
Not Required
Range: 25 to 2500 fpm (0.127 to 12.7 m/s)
Accuracy: ± 5% of reading (5 fpm @100 fpm)
( 0.0254 m/s @ 0.508 m/s)
Resolution: 1 fpm (0.00508 m/s)
Data Interval: Instrument shall be capable of
data logging and data output at a minimum of
one (1) second intervals.
A digital thermal anemometer with the following
characteristics:
12 Months
Range: 0 to 6000 fpm (0 to 30.5 m/s)
Accuracy: ±3 % or ± 3 fpm (0.0152 m/s)
(whichever is greater)
Resolution: 1 fpm (0.00508 m/s)
Data Interval: Instrument shall be capable of
data logging and data output at a minimum of
one (1) second intervals.
Airflow
Velocity Tests
– Response
Time (VAV)
(Section 9.3
Equipment Stand
Stationary stand (ring stand) that will allow the
airflow face velocity measuring device to be
secured.
Not Required
Velocity Measuring
Instrument
(One of the following Shall
be provided)
A digital thermal anemometer with the following
characteristics:
12 Months
Range: 0 to 6000 fpm (0 to 30.5 m/s)
Accuracy: ±3 % or ± 3 fpm (0.0152 m/s)
(whichever is greater)
Resolution: 1 fpm (0.00508 m/s)
Data Interval: Instrument shall be capable of
data logging and data output at a minimum of
one (1) second intervals.
Digital manometer with either a Pitot tube or an
airfoil-type probe. The digital manometer shall
be capable of storing / downloading data to a
computer or printer and shall have the following
characteristics:
Range: -15.0 to +15.0 inches w.c.
(-3.7 to + 3.7 kPa)
Accuracy: ±1 % of reading and ± 0.005 inches
w.c. (1.25 Pa)
Resolution: 0.001 inch w.c. (0.25 Pa)
Data Interval: Instrument shall be capable of
data logging and data output at a minimum of
one (1) second intervals.
16
12 Months
(Meter Only)
NEBB FHT PROCEDURAL STANDARDS
Test
Air Flow
Visualization
Tests – Local
Challenge
(Section 10.2)
Air Flow
Visualization
Tests – Large
Volume
Challenge
(Section 10.3)
Instruments &
Equipment
Small Smoke Source
(One of the following Shall
be provided)
Video Recorder (Optional)
Large Smoke Source
Generator
(one of the following Shall
be provided)
SECTION 4
STANDARDS FOR EQUIPMENT,
INSTRUMENTATION AND CALIBRATION
Description
Puffer – Disposal flexible dispenser containing
powder-based material
Smoke Pen – Smoke emitting wick
Not Required
Smoke Stick/Bottle - A smoke stick/bottle
containing titanium tetrachloride.
Not Required
Other Smoke Source - Any device that can
generate a small relatively neutrally buoyant
smoke source.
Not Required
An aerosol generator that can aerosolize
artificial liquid medium utilizing compressed air
and Laskin nozzle.
Smoke Generator, such as a theatrical smoke
generator with a fluid approved by the owner,
designer or AHJ.
Video Recorder (Optional)
Tracer Gas
Containment
Tests
(Section 11.2)
Calibration
Interval
Not Required
Not Required
Not Required
Not Required
Not Required
Detection Calibrator
A device used to calibrate the detection
instrument in accordance with manufacturer’s
specifications.
When
Required
Ejector System w/critical
orifice
Ejector system with critical orifice Shall conform
to the requirements as indicated in the current
edition of ASHRAE Standard 110. See
Appendix C for instrument specifications.
Not Required
Orifice Calibrator
(One of the following Shall
be provided)
Mechanical device
Range: 0 – 15 L/m
Accuracy: ± 0.1 L/m
Resolution: ± 0.1 L/m
12 months
Flow Meter (measurements shall be adjusted for
specific tracer gas)
Range: 1 – 10 L/m
Accuracy: ± 3%
Resolution: ± 0.5 L/m
Not Required
Sulfur Hexaflouride (SF6) Commercial grade
(Minimum purity of 99%)
Not Required
Other acceptable gas may be used and should
be approximately the same molecular weight,
stability, and grade as SF6. Other acceptable
gas shall be approved by the owner, designer,
or AHJ.
Not Required
Tracer Gas
(One of the following Shall
be provided)
17
NEBB FHT PROCEDURAL STANDARDS
Test
Tracer Gas
Containment
Tests (Cont’d)
(Section 11.2)
Instruments &
Equipment
Mannequin
SECTION 4
STANDARDS FOR EQUIPMENT,
INSTRUMENTATION AND CALIBRATION
Description
A three-dimensional mannequin (torso) shall be
fully clothed that would replicate a normal
operator complete with laboratory coat. The
height must be adjustable to meet the height
requirements of the various hood configurations;
i.e. standard bench hood, ADA height, walk, etc.
Probe shall be placed in the normal breathing
zone based on the various heights.
Video Recorder (Optional)
Tracer Gas Detection
Instrument
(One of the following Shall
be provided)
Calibration
Interval
Not Required
Not Required
Spectrophotometer - A digital, single beam,
infrared spectrophotometer consisting of a
portable gas analyzer and a separate ac/dc
converter. The spectrophotometer must be
capable of measuring sulfur hexaflouride (SF6),
or other approved tracer gas and display in
concentration measurement units (ppm).
The minimum response time shall be 1 second
and capable of interfacing with a data logger /
computer to collect readings.
12 Months
Accuracy: ±15% of reading between five times
minimum detectable concentration and the
upper value range.
Noise: Maximum of 0.004 absorbance units
(AU) with 20.25 m pathlengths at 12.0 μm
wavelength and with AgBr lenses at 75°F (23°
C) operating temperature.
Drift: Maximum of 0.004 AU per 8 hours
The internal diameter of the probe tip shall be
less than 0.5 inches (12mm).
The detection instrument’s calibration shall be
capable of being field-verified.
Electron Capture Detector (Leak Meter) – The
unit shall be configured to measure sulfur
hexaflouride (SF6), or other approved tracer gas
and display in concentration measurement units
(ppm).
The minimum detection range shall be 0.01 ppm
The minimum resolution shall be 0.01 ppm
The minimum response time shall be 1 second
and capable of interfacing with a data logger /
computer to collect readings.
The minimum accuracy shall be ±25% for
readings between 0.05 ppm to 0.1 ppm and ±
10% for readings above 0.1 ppm
The internal diameter of the probe tip shall be
less than 0.5 inches (12mm).
The detection instrument’s calibration shall be
capable of being field-verified.
18
12 Months
SECTION 5 STANDARDS FOR
REPORTS AND FORMS
5.1 REPORTS
The NEBB Procedural Standards for Fume Hood Performance Testing establishes minimum
requirements of a NEBB Certified FHT Report. The standards have been developed and written
using “Shall, Should, and May” language. It is important to note these particular words throughout
this document and how they pertain to NEBB Procedural Standards.
NEBB does not require the use of NEBB produced forms. Customized forms are acceptable
based on the data acquisition requirements of this section. Where contract document data reporting
requirements exceed the minimum requirements of NEBB, the NEBB Certified FHT Firm is
responsible to meet the requirements of the contract documents. NEBB has created sample FHT
reporting forms that are available to be downloaded from the NEBB website at www.nebb.org.
NEBB Fume Hood Performance Testing Reports shall include the following information:
A. REPORT TITLE
B. REPORT CERTIFICATION
C. TABLE OF CONTENTS
D. REPORT SUMMARY / REMARKS
E. APPROPRIATE FORMS
F. INSTRUMENT CALIBRATION
G. ABBREVIATIONS
5.2 REQUIRED DATA
Listed below are the requirements for each NEBB Certified FHT Report in Shall, Should, and May
language.
5.2.1 REPORT TITLE
Shall Data: The heading: “Certified Fume Hood Performance Testing Report”; Project Name,
Address, NEBB Certified FHT Firm Name, Address, Contact Information and Certification Number.
May Data: Architect Name, Address and Contact Information; Engineer Name, Address, and Contact
Information; HVAC Contractor Name, Address and Contact Information.
19
NEBB FHT PROCEDURAL STANDARDS
SECTION 5
STANDARDS FOR REPORTS AND FORMS
5.2.2 REPORT CERTIFICATION
The certification page SHALL bear the stamp of the NEBB Certified FHT Professional. The stamp on
the certification page SHALL be signed as evidence that the NEBB Certified Professional has
reviewed and accepted the report. Signature stamps are specifically prohibited.
Shall Data: Project Name; Certifying NEBB Certified FHT Professional’s Name; Firm Name;
Certification Number; Expiration Date; Certifying NEBB Certified FHT Professional’s NEBB Stamp
(signed & dated); and either of the following exact certification verbiage.
Where fume hood performance testing was performed in complete accordance with the requirements
of this Procedural Standard, the following exact verbiage shall be used on the Report Certification
page:
"THE DATA PRESENTED IN THIS REPORT IS A RECORD OF THE FUME HOOD PERFORMANCE
TESTING OBTAINED IN ACCORDANCE WITH THE REQUIREMENTS OF THE CURRENT
EDITION OF THE NEBB PROCEDURAL STANDARDS FOR FUME HOOD PERFORMANCE
TESTING. ANY VARIANCES FROM DESIGN / OR INDUSTRY STANDARDS WHICH EXCEED THE
LIMITS SET BY THE CONTRACT DOCUMENTS, OR WHICH EXCEED THE LIMITS AGREED TO
BETWEEN THE OWNER AND THE NEBB CERTIFIED FHT FIRM ARE NOTED THROUGHOUT
THIS REPORT AND / OR IN THE REPORT PROJECT SUMMARY."
NEBB recommends that fume hood testing should be performed in accordance with the requirements
of these Procedural Standards and that all three of the primary tests (Airflow Velocity Tests, Airflow
Visualizations Tests, and Tracer Gas Containment Tests) are performed. There may be cases where
the scope of the work requires testing to other industry standards, or requires testing to a scope of
work that is specified or as agreed to between the owner / buyer and the NEBB Certified FHT Firm.
Under these conditions, a NEBB Certified FHT Firm may still issues a NEBB Certified FHT Report, but
the procedural variances SHALL be clearly delineated in the project scope of work and the above
Certification Statement SHALL be modified to reflect the actual scope of work or other industry testing
standards to qualify as a NEBB Certified Report. See Section 2.3.1.
Should Data: Disclaimer statement with the following suggested wording:
“The results shown and information given in this report are certified to be accurate and complete to the
extent possible by equipment and procedures used on this date.
___(Insert Company Name)_____________________________________ warrants that the equipment
or system listed above and/or identified in this report is operating at the specified levels as shown, at and
only at this time, and makes no other warranties, stated or implied, concerning the continued
performance, operation or safety in use of this equipment past this time.”
Note: The Certification Statement and the Disclaimer Statement may be included on the report title
page or on a separate certification page.
5.2.3 TABLE OF CONTENTS
The table of contents shall serve as a guide to the organization of the FHT report.
Shall Data: Page numbers of system and component information in the report.
20
NEBB FHT PROCEDURAL STANDARDS
SECTION 5
STANDARDS FOR REPORTS AND FORMS
5.2.4 REPORT SUMMARY / REMARKS
A NEBB Certified FHT Report includes a narrative description of test methods and system set-up
conditions established prior to testing. The narrative should explain the rational for system
parameters, such as the Test Setup Mode, and the steps taken to achieve the desired set-up.
This section also includes a listing of deficiencies in the summary and identifies the appropriate pages
in the report. Deficiencies or other issues that are critical in nature relative to occupant health or
facility safety shall be “red tagged” and brought to the immediate attention of the AHJ. The NEBB
Certified FHT Firm SHALL NOT wait to identify these issues on a final FHT Report.
Shall Data: Summary of all items that exceed Contract Document tolerances or any other items that
require discussion / explanation.
5.2.5 ALL REPORT PAGES
All tested items included in the NEBB FHT Report shall be clearly identified with its associated fume
hood designation number or other unique descriptor.
The location of each tested item shall also be identified on each report page. The location identifier
should be the room number, the space number or other unique descriptor to clearly identify the tested
item.
The method of identification shall use schematic diagrams, mechanical plans where permissible, or a
narrative description. Each data form supplied in a NEBB FHT Report shall include the name of the
responsible technician / NEBB Certified FHT Professional who reported the information, and the time
period the data was collected.
Shall Data: Project name. All pages shall be numbered consecutively.
May Data: Remarks section to record any information pertinent to the data reported on the data
sheet.
5.2.6 INSTRUMENT CALIBRATION
This is an overall listing of the instruments that will be used to verify the reported data.
Shall Data:
Instrument type
Instrument manufacturer
Instrument model number
Instrument serial number
Date of instrument calibration
Tracer Gas purity certification
5.2.7 ABBREVIATIONS
This is a list of definitions of the relevant abbreviations used in the report.
Shall Data: A listing of all abbreviations and their definition as used in the report.
21
NEBB FHT PROCEDURAL STANDARDS
SECTION 5
STANDARDS FOR REPORTS AND FORMS
5.2.8 AIRFLOW VELOCITY TEST REPORT DATA – CONSTANT AIR VOLUME SYSTEMS
Airflow velocity tests shall be presented in graphical or tabular format for each measurement plane
and location and the data shall be reported on the test reporting form(s).
Shall Data:
Technician Name
Date of Test
Test Setup Mode
Sash Configuration
Design Opening Sash Position (Height and
Width)
Design Airflow Face Velocity (fpm) (m/s)
Average Airflow Face Velocity at each grid
location (fpm) (m/s)
Average Airflow Face Velocity (fpm) (m/s)
Highest Airflow Face Velocity (fpm) (m/s)
Lowest Airflow Face Velocity (fpm) (m/s)
Test Instrumentation
Acceptance Criteria
Should Data:
Sash Openings other than Design Conditions and associated results
Temperature (°F) (°C)
Altitude and Correction Factor
Room Layout Drawing
5.2.9 AIRFLOW VELOCITY TEST REPORT DATA – VAV SYSTEMS
Airflow velocity tests shall be presented in graphical or tabular format for each measurement plane
and location and the data shall be reported on the test reporting form(s).
Shall Data:
Technician Name
Date of Test
Test Setup Mode
Sash Configuration
Design Opening Sash Position (Height and
Width)
Design Airflow Face Velocity (fpm) (m/s)
Average Airflow Face Velocity at each grid
location (fpm) (m/s)
Average Face Velocity (fpm) (m/s)
Highest Airflow Face Velocity (fpm) (m/s)
Lowest Airflow Face Velocity (fpm) (m/s)
Test Instrumentation
Test results reported at 25%, 50% and
100% of specified conditions
Speed of Response (in seconds) (3 cycles)
Low Value of Range (in percentage)
High Value of Range (in percentage)
Relative Range (in percentage)
Repeatability (in percentage)
Time to Steady State (in seconds) (3 cycles)
Test Method (exhaust airflow velocity
method or fume hood plenum airflow
velocity method)
Acceptance Criteria
Should Data:
Sash Openings other than Design Conditions and associated results
Temperature (°F) (°C)
Altitude and Correction Factor
Room Layout Drawing
22
NEBB FHT PROCEDURAL STANDARDS
SECTION 5
STANDARDS FOR REPORTS AND FORMS
5.2.10 AIRFLOW VISUALIZATION TEST REPORT DATA – LOCAL CHALLENGE
Shall Data:
Technician Name
Date of Test
Test Setup Mode
Sash Configuration
Sash Opening Height and Width
Challenge Medium Used
Narrative description of actual visual test
results including Statement of Pass/Fail
Test Instrumentation
Acceptance Criteria
Should Data:
Room Layout Drawing
May Data:
Video tape of actual test
5.2.11 AIRFLOW VISUALIZATION TEST REPORT DATA – LARGE VOLUME CHALLENGE
Shall Data:
Technician Name
Date of Test
Test Setup Mode
Sash Configuration
Sash Opening Height and Width
Challenge Medium Used
Narrative description of actual visual test
results including Statement of Pass/Fail
Test Instrumentation
Acceptance Criteria
Should Data:
Room Layout Drawing
May Data:
Video tape of actual test
5.2.12 TRACER GAS CONTAINMENT TEST REPORT DATA – STATIC MODE
Shall Data:
Technician Name
Date of test
Time of test
Test Setup Mode
Sash Configuration
Sash Opening Height and Width
Room Layout Drawing
Graphical display of each test
Tracer Gas Release Rate
Test Instrumentation
Report all individual readings, the average
and peak at each sample location
Report the Performance Rating and compare
to the Acceptance Rating. Tests results
that exceed acceptance ratings shall be
noted in the report.
May Data:
Video tape of actual test
23
NEBB FHT PROCEDURAL STANDARDS
SECTION 5
STANDARDS FOR REPORTS AND FORMS
5.2.13 TRACER GAS CONTAINMENT TEST REPORT DATA – SASH MOVEMENT EFFECT
Shall Data:
Technician Name
Date of test
Time of test
Test Setup Mode
Sash Configuration
Sash Opening Height and Width
Room Layout Drawing
Graphical display of each test
Tracer Gas Release Rate
Test Instrumentation
Report all individual readings
Report the maximum 45 second rolling
average associated with each opening of
the sash
Report the Sash Movement Performance
Effect Rating
If Acceptance Rating has been defined,
test results that exceed acceptance
rating shall be noted in the report
May Data:
Video tape of actual test
5.2.14 TRACER GAS CONTAINMENT TEST REPORT DATA – PERIMETER SCAN
Shall Data:
Technician Name
Date of test
Time of test
Test Setup Mode
Sash Configuration
Sash Opening Height and Width
Room Layout Drawing
Fume Hood Face Schematic
Report any measurable leakage
Report the location and magnitude of the
leakage
Tracer Gas Release Rate
Test Instrumentation
If Acceptance Ratings have been defined,
tests results that exceed acceptance
ratings shall be noted in the report
May Data:
Video tape of actual test
5.2.15 OTHER FUME HOOD PERFORMANCE TEST REPORT DATA
Shall Data:
As agreed to between the Owner and the NEBB Certified FHT Firm
24
PART 2 - PROCEDURES
SECTION 6 LABORATORY AND
CLEANROOM SAFETY
6.1 INTRODUCTION
A health and safety program is a definite plan of action designed to prevent accidents and
occupational diseases. A health and safety program should include the elements required by all
current health and safety legislation as a minimum. This document summarizes the general elements
of a health and safety program. This should help NEBB firms to develop programs to deal with their
specific needs. Because many small and medium-sized enterprises lack the resources of larger
organizations, it is even more vital that small and medium-sized enterprises involve all employees in
health and safety activities. The more comprehensive the program is, the more employee
involvement can be expected.
The health and safety program discussed in this section is a guideline. The project specific safety
program shall be as specified in the contract documents or as agreed to between the Owner/Buyer and
the NEBB Certified FHT Firm.
Most often the NEBB Certified FHT firm will be required to follow the client’s project specific safety
program; however in the absence of this project specific safety program, the firm’s Standard
Operating Procedures (SOP) for a health and safety program SHALL be followed. For this reason,
the NEBB Certified FHT Firm SHALL be responsible for creating their own SOP for Safety and
develop it into a Standard Operating Procedure (SOP) for their firm. At a minimum, the NEBB
Certified FHT Firm’s SOP for Laboratory and Cleanroom Safety SHOULD cover design and
implementation, responsibilities and elements of the plan as addressed below.
6.2 DESIGNING A HEALTH AND SAFETY PROGRAM
6.2.1 DESIGNING A PROGRAM POLICY
A NEBB Certified FHT Firm’s health and safety policy is a statement of principles and general rules
that serve as guideslines for action.
6.2.1.1 The policy SHOULD mention:
a.
b.
c.
d.
e.
f.
g.
Management's commitment to protect the safety and health of employees
The objectives of the program
The organization's basic health and safety philosophy
Who is accountable for health and safety programs
The general responsibilities of all employees
That health and safety shall not be sacrificed for expediency
That unacceptable performance of health and safety conduct will not be tolerated
25
NEBB FHT PROCEDURAL STANDARDS
SECTION 6
LABORATORY AND CLEANROOM SAFETY
6.2.1.2 The policy SHOULD be:
a.
b.
c.
d.
e.
Stated in clear, unambiguous, and unequivocal terms
Signed by the incumbent chief executive officer
Kept up-to-date
Communicated to each employee
Adhered to in all work activities
6.2.2 DESIGNING A TRAINING PROGRAM
The objective of training is to make the implementation of health and safety policies into specific job
practices and accepted practice. It also raises awareness and skill levels of a technician to an
acceptable standard.
6.2.2.1 Occasions when employee training SHOULD be required are:
a.
b.
c.
d.
e.
Commencement of employment
Reassignment or transfer to a new job
Introduction of new equipment, processes, or procedures
Inadequate performance
Customer and job site related chemical or biological hazards, equipment, processes, or
procedures.
6.2.2.2 The NEBB Certified FHT Firm SHOULD have the following topics included in the safety
training:
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
Safety and the supervisor
Know your accident problems
Human relations
Maintaining interest in safety
Instructing for safety
Industrial hygiene
Personal protective equipment
Industrial housekeeping
Material handling and storage
Guarding machines and mechanisms
Hand and portable power tools
Fire protection
6.2.3 ESSENTIALS OF THE HEALTH AND SAFETY PROGRAM
While different NEBB Certified FHT Firms will have different needs and requirements in their health
and safety program, the following basic items MAY be considered in each case:
a.
b.
c.
d.
e.
f.
g.
h.
Individual responsibility
Occupational health and / or safety representative
Health and safety rules
Correct work procedures
Employee orientation
Training
Workplace inspections
Reporting and investigating accidents
26
NEBB FHT PROCEDURAL STANDARDS
i.
j.
k.
l.
SECTION 6
LABORATORY AND CLEANROOM SAFETY
Emergency procedures
Medical and first aid
Health and safety incentives
Workplace specific items
6.3 RESPONSIBILITIES
6.3.1 INDIVIDUAL HEALTH & SAFETY RESPONSIBILITIES
Health and safety is the joint responsibility of both management and technicians. All health and safety
activities are based on specific individual responsibilities. Responsibility may be defined as an
individual's obligation to carry out assigned duties. Authority implies the right to make decisions and
the power to direct others. The NEBB Certified FHT Firm MAY elect to have its Safety Officer
manage the responsibilities in lieu of the NEBB Certified FHT Professional.
6.3.1.1 NEBB Certified Professionals / Safety Officer Responsibilities
To fulfill their responsibilities, the NEBB Certified FHT Professional / Safety Officer SHOULD:
a. Instruct workers to follow safe work practices
b. Enforce health and safety regulations
c. Correct unsafe acts and unsafe conditions
d. Ensure that only authorized, adequately trained workers operate equipment
e. Report and investigating all accidents/incidents
f. Inspect own area and taking remedial action to minimize or eliminate hazards
g. Ensure equipment is properly maintained
h. Update and maintain company material safety data sheets (MSDS)
i. Promote safety awareness in workers
j. Provide a safe and healthful workplace
k. Establish and maintaining a health and safety program
l. Ensure workers are trained or certified, as required
m. Report accidents and cases of occupational disease to the appropriate authority
n. Ensure access to medical and first aid facilities are available
o. Ensure personal protective equipment is available
p. Provide workers with health and safety information
q. Evaluate health and safety performance of technicians
r. Advise all employees on health and safety matters
s. Coordinate interdepartmental health and safety activities
t. Provide health and safety training
u. Conduct research on special problems
v. Attend health and safety committee meetings as a resource person
6.3.1.2 Field Technician Responsibilities
To fulfill their responsibilities, the field technicians SHOULD:
a. Use personal protection and safety equipment as required by the client project specific safety
program or the NEBB firm’s SOP
b. Follow safe work procedures
c. Possess company material safety data sheets (MSDS)
d. Know and comply with all regulations
e. Report any injury or illness immediately
f. Report unsafe acts and unsafe conditions
g. Participate in joint health and safety committees
h. Know what their responsibilities are (communication required)
27
NEBB FHT PROCEDURAL STANDARDS
i.
j.
SECTION 6
LABORATORY AND CLEANROOM SAFETY
Have sufficient authority to carry them out (organizational issue)
Have the required ability and competence (training or certification required)
6.4 ELEMENTS OF THE PROGRAM
The NEBB Certified FHT Professional / Safety Officer SHOULD address the following elements of the
firm’s health and safety program:
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
Establish work procedures
Analyze project hazards
Establish guideline rules
Conduct employee safety orientation
Establish emergency procedures
Establish medical and first aid action plan
Perform routine project site safety audits
Complete project accident / injury reports
Investigate project accidents/ injuries
Establish and enforce return-to-work policy
Promote employee involvement in health and safety programs
6.4.1 PROJECT SPECIFIC ITEMS
Examples of project specific items that SHOULD be included in health and safety programs are:
a.
b.
c.
d.
e.
f.
g.
h.
Material Safety Data Sheets (MSDS)
Lock out procedures
Chemical handling rules
Biological material handling rules
Personal hygiene
Vehicle safety rules
Working alone guidelines
Personal protective equipment requirements
6.4.2 HEALTH AND SAFETY PROGRAM IMPLEMENTATION
A good health and safety program provides a clear set of guidelines for activities that, if followed, will
reduce accidents and cases of occupational disease. A NEBB Certified FHT Professional SHOULD
demonstrate commitment and support the program by:
a. Providing resources such as time, money, and personnel
b. Ensuring that employees receive training or certification as required
c. Making all applicable health and safety information available to all employees entitled to
receive it
d. Including health and safety performance as part of employee performances appraisals at all
levels
e. Attending health and safety meetings
f. The program must be communicated to all employees
g. Special emphasis should be given to new workers, newly appointed NEBB Certified
Professionals
h. Revisions to policies and procedures should be publicized
i. The program should be available in a single written document (However, if separate manuals
have been developed for various elements, such as accident investigation procedures, their
use should be referred to in the main document)
28
SECTION 7 LABORATORY AND
CLEANROOM PROTOCOL
7.1 INTRODUCTION
The purpose of this Section is to provide an overview of the protocol procedures that should be
observed in performing the various tests in cleanrooms and laboratories. In general, there are
protocols and procedures for entry, garment control, tool and equipment entry and gowning procedures.
In addition to entry protocols, there are also protocols and behavior requirements while in the laboratory/
cleanroom spaces. The protocols suggested in this section are guidelines and the final procedures
shall be as specified in the contract documents or as agreed to between the Owner/Buyer and the
NEBB Certified FHT firm.
Most often the NEBB Certified FHT firm will be required to follow the client project specific protocol;
however, in the absence of this project specific protocol, the firm’s SOP for laboratory and cleanroom
protocol shall be followed. For this reason, the NEBB Certified FHT Firm shall be responsible for
creating their own SOP for protocol and develop it into a Standard Operating Procedure (SOP) for
their firm. At a minimum, the NEBB Certified FHT Firm’s SOP for Laboratory and Cleanroom Protocol
should cover: gowning procedures, equipment entrance procedures, and guidelines for employee
conduct.
7.2 LABORATORY AND CLEANROOM PROCEDURES
7.2.1 GOWNING PROCEDURES
The processes and operations that occur in laboratory/cleanroom are unique to that particular owner
and facility. Therefore the gowning procedures may vary to some degree between each cleanroom and
each owner. It is imperative that the facility’s/owner’s SOP be reviewed for the specific gowning
procedure. When it exists, this SOP always takes precedence and shall be followed.
In many cleanroom gowning facilities there are two distinct zones in the gowning area. In some
facilities, the two distinct zones may exist in the same room/space defined by some imaginary boundary.
The initial area will have gloves, hair bonnets and shoe covers. Since the outside surface of the
“cleanroom garments” should be kept as clean as possible, care should be used to avoid touching the
outside of the garment with bare hands, hair and street shoes. This is accomplished by donning gloves,
bouffant head covers and shoe covers before entering the second phase of the gowning area.
It is important to note that laboratories/cleanrooms in the electronics industry may be quite different from
laboratories/cleanrooms in the pharmaceutical and bio-technology industries. While gowning remains
important, a high emphasis is placed on sterility. Cleaning/washing procedures can be much more
rigorous. In some instances, usually associated with bio-containment spaces (i.e. BSL3 and BSL4
labs), street clothes will not be allowed into the room and a complete change of clothing is required.
Upon entering the second area it is important to note that different gowning garments will be used in
different facilities. Since gowning materials differ, there is no hard and fast method that can be outlined
for actual gowning, but typically gowning should be done from the head down. Therefore the hood will
be donned first, and then the garment, then the foot covers. Once the garment is obtained, care should
29
NEBB FHT PROCEDURAL STANDARDS
SECTION 7
LABORATORY AND
CLEANROOM PROTOCOL
be taken to avoid contaminating the exterior surface with the interior of the garment. Proper garment
sizing is also required. Once obtained, the garment user should never allow the garment to touch or
drag on the floor.
7.2.2 EQUIPMENT ENTRANCE PROCEDURES
Tools, instrumentation and equipment also require special preparation before they can be brought into a
laboratory/cleanroom. As with gowning, each facility will have their own methods and requirements for
introducing these items into a cleanroom. It is imperative that the facility/owners SOP be reviewed for
material ingress to their cleanroom. When it exists, this SOP always takes precedence and must be
followed.
Typically there will be a wipe down station for anything entering the cleanroom. There will also be a
wipe down procedure. Often the procedure will involve wipe down with non-contaminating wipes
moistened with de-ionized water and isopropyl alcohol (IPA) or other sterile solvents. The ingress for
equipment may be a separate entrance from the gowning entrance.
7.2.3 LABORATORY/CLEANROOM CONDUCT
Examples of personnel rules used by laboratory/cleanroom operators may be:
a. Clean hands and face before entering clean areas
b. Use lotions and soap containing lanolin to reduce skin flaking
c. Avoid skin contacts with solvents
d. Wearing cosmetics and skin medications may not be permitted
e. Jewelry may not be permitted
f. Smoking, eating and drinking is not permitted
g. Required gowning, masks, gloves and shoe covers to be worn at all times
h. Use proper eye protection
i. Equipment, instruments and materials should be cleaned before entry
j. Non-shedding paper and pens should be used. Pencils and erasers are not permitted
k. Work parts are to be handled only with gloved hands, tweezers, or other methods to avoid
transfer of skin particles and oils
l. Use containers to transfer and/or store materials
30
SECTION 8 OVERVIEW OF
TESTING REQUIREMENTS
8.1 INTRODUCTION
The purpose of this section is to provide an overview of the various tests associated with fume hood
performance testing in accordance with the American Society of Heating Refrigerating and Air
Conditioning Engineers (ASHRAE) Standard 110, Method of Testing Performance of Laboratory Fume
Hoods, and the American National Standards Institute (ANSI) Standard Z9.5, Laboratory Ventilation. An
overview CANNOT provide all of the exacting requirements of these standards. For this reason, the
NEBB Certified FHT Firm SHALL possess copies of the current versions of both of these industry
standards in addition to the NEBB Procedural Standard. Another excellent reference material is the
ASHRAE Handbook chapter on laboratory spaces. See Appendix D for additional references.
The methods and procedures to perform these tests and the results of the tests are a function of the hood
types, fume hood sash configuration styles and test setup modes. Thus a brief overview of these
parameters is also included in this section.
8.2 TEST SETUP PROCEDURES
8.2.1 FUME HOOD TYPES
Fume hoods are manufactured in two basic styles: bench type and walk-in. While most fume hoods
are bench type hoods, walk-in hoods are still required where the physical size of the test apparatus
cannot be contained in a bench style enclosure.
Listed below are the most common types of fume hoods and their applications:
Standard: Airflow volume is relatively constant and airflow face velocity varies as a function of sash
opening. May be furnished with all sash configurations. Common hood type found for almost all
containment applications.
Bypass: Airflow volume and airflow face velocity are relatively constant for all sash openings. As
opening size changes due to changes in sash position, openings at the top and the bottom of the
hood allow the balance of the air to be drawn into the hood while the airflow face velocity remains
constant. May be furnished with all sash configurations.
Common hood type found in most
containment applications.
Auxiliary Air: Airflow volume and airflow face velocity are relatively constant. A plenum is located
above the face of the hood and a connection is provided to receive air from a secondary source other
than environmentally controlled room air. This secondary source can be conditioned or unconditioned
air. These hoods are utilized to achieve energy savings.
Variable Air Volume: The airflow volume is a function of sash position. May be furnished with all sash
configurations. Common hood type found for almost all containment applications.
While the above identify the most common fume hood types, fume hoods types also include: process,
31
NEBB FHT PROCEDURAL STANDARDS
SECTION 8
OVERVIEW OF
TESTING REQUIREMENTS
high-performance, radioisotope, perchloric acid, California, and distillation hoods. All of these fume
hood types are simply variations of the four common types previously identified with some
modifications. A process hood is basically a standard hood without a sash. ASHRAE also identifies a
canopy hood as a type of fume hood. This is really a misnomer as a canopy hood is related to a
kitchen style grease hood. Like a kitchen hood, the purpose of a canopy hood is to remove heat not
fumes. Again, consult the ASHRAE Handbooks or various manufacturers’ details and submittals
data.
8.2.2 FUME HOOD SASH CONFIGURATIONS
Fume hood sashes are normally made from safety glass. The purpose of the fume hood sash is twofold: observation and protection. Sash configurations are sometimes identified as sash opening types
or sash styles. The wording sash configuration is the most appropriate. Fume hoods can be
manufactured in three various sash configurations: horizontal, vertical, and combination. The number
of sashes can vary and all sashes may not be operable.
Horizontal Sash: In these fume hoods the sash movement is horizontal. The arrangement can be
where one or more of the sashes can be opened at any one time and the sashes can be located at
any position in the horizontal tracks.
Vertical Sash. In these fume hoods the sash movement is vertical. In a vertical sash configuration,
there may be one or more sashes and they can be moved completely down for full closed to
completely up to full open or any position in between.
Combination Sash. As the name implies, the sashes are a combination of vertical and horizontal
sashes that serve the fume hood.
8.2.3 TEST SETUP (TEST SETUP MODE)
Test Setup is sometimes identified as the Test Setup Mode. Test Setup is defined as the condition
that the fume hood will be during the actual test. There are three test setups: As-Manufactured (AM),
As-Installed (AI), and As-Used (AU). It is important to note the differences between the three test
setups because the various test procedures, reporting and results are unique for each test setup.
As-Manufactured (AM): With this test setup, the fume hood is tested at the manufacturer’s facility or
under conditions that would replicate those conditions. The hood and work surface shall be void of all
process equipment, apparatus and chemicals.
As-Installed (AI): With this test setup, the actual fume hood is tested in its installed, operating
condition. All supply, exhaust and return air systems are installed, operable and under control. The
hood and work surface shall be void of all process equipment, apparatus and chemicals.
As-Used (AU): This test setup is the same as the As-Installed setup except the hood is being utilized
for actual process work. Experiment equipment, chemicals and processes are being carried out
inside the hood while the fume hood performance testing is being performed. This means that all
normal operating equipment within the hood shall be activated and operational including items such
as all heat and vapor producing appliances, physical obstructions, etc.
32
NEBB FHT PROCEDURAL STANDARDS
SECTION 8
OVERVIEW OF
TESTING REQUIREMENTS
When doing fume hood performance testing in accordance with the NEBB Procedural Standards for
Fume Hood Performance Testing, the test setup shall be defined prior to testing. Test setup shall be as
specified in the contract documents or as agreed to between the Owner/Buyer and the NEBB Certified
FHT Firm.
8.3 ASHRAE STANDARD 110
The Forward of the current ASHRAE 110 Standard states that: “…The performance of a laboratory
hood in providing protection for the worker at the face of the hood is strongly influenced by the
aerodynamic design of the hood, the method of operation of the hood, the stability of the exhaust
ventilation system, the supply ventilation of the laboratory room, the work practices of the user, and by
other features of the laboratory in which it is installed. Therefore, there is a need for a performance
test that can be used to evaluate the performance of a laboratory hood in the ideal environment and in
the field to establish an "as used" performance rating, including the influences of the laboratory
arrangement and its ventilation system.
This standard defines a reproducible method of testing laboratory hoods. It does not define safe
procedures. However, laboratory hoods are considered by many to be the primary safety devices in
conducting laboratory operations.
There are many important factors in the safe operation of laboratory hoods that are not described in
this standard.”
There are several things about the ASHRAE standard that should be discussed. ASHRAE 110 DOES
define a reproducible method of testing. It clearly defines the requirements for the three unique tests:
Airflow Velocity Tests, Airflow Visualization Tests, and Tracer Gas Containment Tests. The ASHRAE
standard DOES NOT define Pass/Fail criteria for the Airflow Face Velocity Tests. It DOES provide a
Pass/Fail criteria that may, or may not, be subjective, for the Airflow Visualization Tests. And, while it
DOES provide a quantitative rating of the Tracer Gas Containment Tests, the standard DOES NOT
include an associated Pass/Fail criteria for this these tests.
Another feature of the ASHRAE tests is implied. The tests should be performed in order: Airflow
Velocity Tests, Airflow Visualization Tests and finally the Tracer Gas Containment Tests. It is
somewhat implied that if an unsafe condition exists at any testing level, the subsequent test should
NOT be performed until the condition is remedied.
As previously stated in Sections 2 and 3, the scope of testing services should be defined by the
Design Professional. Where the scope is not defined, the scope shall be as agreed to between the
Owner/Buyer and the NEBB Certified FHT Firm.
The NEBB Fume Hood Performance Testing program and ASHRAE Standard 110 are flexible. A fume
hood may be tested for airflow velocity only and a report could be issued with those test results. Not all
three tests have to be performed. As an example, an owner/buyer may want to have a fume hood
tested for Airflow Face Velocity Tests only and dictate the acceptable criteria for the tests, and / or a
procedure that is not in concert with the requirements of NEBB or ASHRAE. The NEBB Certified FHT
Firm can perform the tests in accordance with NEBB’s requirements and can issue a certified report
documenting the testing performed.
As previously stated in Section 8.1, the NEBB Certified FHT Professional shall be familiar with the
33
NEBB FHT PROCEDURAL STANDARDS
SECTION 8
OVERVIEW OF
TESTING REQUIREMENTS
requirements of ASHRAE Standard 110.
8.4 ANSI STANDARD Z9.5
The Forward of the ANSI Z9.5 Standard states that: “This standard describes required and
recommended practices for the design and operation of laboratory ventilation systems used for control
of exposure to airborne contaminants. It is intended for use by employers, architects, industrial
hygienists, safety engineers, Chemical Hygiene Officers, Environmental Health and Safety
Professionals, ventilation system designers, facilities engineers, maintenance personnel, and testing
and balance personnel. It is compatible with the ACGIH Industrial Ventilation: A Manual of
Recommended Practices, ASHRAE ventilation standards, and other recognized standards of good
practice.”
The ANSI standard is presented in two-column format. The left column states the requirements of the
standard as expressed by the use of “shall.” In the right column is a commentary and/or descriptive
explanation of the requirements and suggested good practices. The right column contains examples
that are expressed by the word “should.”
This is same as the language of the NEBB Procedural Standard.
Where the ASHRAE standard is very task oriented, the ANSI standard is more results oriented. The
ANSI standard has an excellent section on airflow face velocities with suggested criteria. The
Forward of the ANSI standard clearly states that “Requirements should be considered minimum
criteria and can be adapted to the needs of the User establishment. It is the intent of the standard to
allow and encourage innovation provided the main objective of the standard, “control of exposure to
airborne contaminants,” is met. Demonstrably equal or better approaches are acceptable. When
standard provisions are in conflict, the more stringent applies.”
The ANSI standard DOES contain suggested criteria for airflow velocity, but DOES NOT contain any
exacting acceptance requirements for airflow velocity. It also DOES NOT contain any acceptance
criteria related to the Airflow Visualization Tests. It DOES contain acceptance criteria for the Tracer
Gas Containment Tests.
The ANSI standard is another excellent reference source for information regarding fume hoods, biosafety cabinets and laboratory ventilation system design.
8.5 PRELIMINARY TEST PROCEDURES
The NEBB Certified FHT Professional should plan the work by preparing an agenda prior to performing
the various fume hood tests identified in Section 9, 10, 11, and 12. The agenda should include planning
for the testing, identifying the required instrumentation and equipment, safety and health issues, owner
requirements, etc. The preparatory work should also include a thorough review of the engineering
design documents, plans, specifications and submittals. A site visit is advisable to verify that all
construction activities are complete, and all necessary systems and equipment are operational. If
deficiencies are found, a letter should be sent to the owner/designer identifying the conditions that may
preclude proper fume hood testing.
34
SECTION 9 AIRFLOW
VELOCITY TESTS
PROCEDURES
9.1 INTRODUCTION
The purpose of these tests is to validate that the average airflow face velocity meets the specified
requirements at the required sash configuration. The required sash configuration condition may be
dictated by the Owner, the Specifier, local code requirements, or the AHJ. The sash configuration
determined by the Airflow Face Velocity Test will determine the operating sash configuration. Prior to
conducting the Airflow Velocity Tests, all mechanical ventilation systems serving the space shall be
functional and operating in the normal mode. This includes, but is not limited to, the supply, return and
exhaust systems, air terminal boxes, air outlets, air inlets, etc. serving the space. The automatic control
equipment and building automation systems shall be operational, calibrated, and commissioned. The
TAB work shall be completed.
Additionally, the operation of the space shall replicate the normal mode of operation during the tests.
This would include that all SOP’s are followed relating to safety, hood operation, equipment in operation
during the tests, etc.
Finally, the Airflow Velocity Tests should be conducted prior to performing the Airflow Visualization Tests
and the Tracer Gas Containment Tests.
9.2 AIRFLOW FACE VELOCITY TEST – CONSTANT AIR VOLUME (CAV)
FUME HOOD
9.2.1 INSTRUMENTS AND EQUIPMENT
9.2.1.1 Provide airflow velocity measuring instruments that conform to the requirements of Table 4-1.
9.2.1.2 Provide a linear measuring device.
9.2.1.3 Provide an equipment stand.
9.2.2 TEST PROCEDURES (Average Airflow Face Velocity)
9.2.2.1 Set hood to the design opening sash position as specified in the contract documents or as
agreed to between the Owner/Buyer and the NEBB Certified FHT Firm. Measure the area of the
opening. The area shall be determined as follows:
Height: Height shall be based on the dimension from the bottom most part of the sash to the
work surface located in a straight plane directly beneath the sash for vertical sashes,
or the opening between horizontal tracks on horizontal sashes.
Width:
Width shall be based on the interior dimensions of the design sash opening.
35
NEBB FHT PROCEDURAL STANDARDS
SECTION 9
AIRFLOW VELOCITY
TEST PROCEDURES
9.2.2.2 Determine a grid pattern of equal areas by dividing the opening into horizontal and vertical
dimensions. Each equal area grid location shall be a maximum of one (1) square foot (0.093 m²) with
no dimension larger than 13” (330 mm). See Appendix E for an example of the proper method to
determine a grid pattern.
9.2.2.3 Place the instrument on the equipment stand and locate the instrument in the center of each
grid location in the plane of the sash opening and normal to the plane. All personnel should stand
clear of the hood so as not to affect the airflow.
9.2.2.4 Measure and record the airflow face velocities at the center of each grid location. Each grid
location shall have a minimum of 20 samples taken at one second intervals. Average the 20 samples
at each location to determine the airflow face velocity at each grid location. Report the average of each
grid location.
9.2.2.5 The airflow face velocity is determined by averaging the airflow face velocity from each grid
location. Report the average airflow face velocity and the highest and lowest grid location average.
9.2.2.6 If the actual average airflow face velocity as determined above does not meet the acceptance
criteria as identified in Section 9.2.3, remedial work, if required, shall be as specified in the contract
documents or as agreed to between the owner/buyer and the NEBB Certified FHT Firm.
9.2.2.7 For reference and safety purposes, the fume hood airflow face velocity should also be
determined at a full open sash position. The procedure to be followed shall be as previously indicated
above.
9.2.2.8 It should be noted that the total fume hood exhaust volume is NOT equal to the average airflow
face velocity being captured through the sash opening. Additionally, air will enter the hood under the
airfoil and may enter the hood through leakage and other openings.
9.2.3 ACCEPTANCE
The acceptance criteria shall be as specified in the contract documents or as agreed to between the
Owner/Buyer and the NEBB Certified FHT Firm.
9.2.4 REPORTING
See Section 5.2.8 for reporting requirements.
9.3 AIRFLOW FACE VELOCITY TEST – VARIABLE AIR VOLUME (VAV)
FUME HOOD
Variable air volume hoods are tested in a similar manner to constant air volume hoods for determining
airflow face velocity. Additionally, VAV hoods are also tested to determine response time to return to a
near steady-state condition after a change in sash position.
Prior to conducting the Airflow Velocity Test for a VAV fume hood, all controls, sensors and
components shall be verified as to their operation, calibration and proper sequencing.
9.3.1 INSTRUMENTS AND EQUIPMENT
9.3.1.1 Provide airflow velocity measuring instruments that conform to the requirements of Table 4-1.
36
NEBB FHT PROCEDURAL STANDARDS
SECTION 9
AIRFLOW VELOCITY
TEST PROCEDURES
9.3.1.2 Provide a linear measuring device.
9.3.1.3 Provide an equipment stand.
9.3.2 TEST PROCEDURES (Average Airflow Face Velocity)
9.3.2.1 Set hood to the design opening sash position as specified in the contract documents or as
agreed to between the Owner/Buyer and the NEBB Certified FHT Firm. Measure the area of the
opening. The area shall be determined as follows:
Height: Height shall be based on the dimension from the bottom most part of the sash to the
work surface located in a straight plane directly beneath the sash for vertical sashes,
or the opening between horizontal tracks on horizontal sashes.
Width:
Width shall be based on the interior dimensions of the design sash opening.
9.3.2.2 Determine a grid pattern of equal areas by dividing the opening into horizontal and vertical
dimensions. Each equal area grid location shall be a maximum of one (1) square foot (0.093 m²) with
no dimension larger than 13” (330 mm). See Appendix E for an example of the proper method to
determine a grid pattern.
9.3.2.3 Place the instrument on the equipment stand and locate the instrument in the center of each
grid location in the plane of the sash opening and normal to the plane. All personnel should stand
clear of the hood so as not to affect the airflow.
9.3.2.4 Measure and record the airflow face velocities at the center of each grid location. Each grid
location shall have a minimum of 20 samples taken at one second intervals. Average the 20 samples
at each location to determine the airflow face velocity at each grid location.
9.3.2.5 The airflow face velocity is determined by averaging the airflow face velocity from each grid
location. Report the average airflow face velocity and the highest and lowest grid location average.
9.3.2.6 If the actual average airflow face velocity as determined above does not meet the acceptance
criteria as identified in Section 9.3.4, remedial work, if required, shall be as specified in the contract
documents or as agreed to between the owner/buyer and the NEBB Certified FHT Firm.
9.3.2.7 For reference and safety purposes, the fume hood airflow face velocity should also be
determined at a full open sash position. The procedure to be followed shall be as previously indicated
above.
9.3.2.8 Reduce the sash position to 50% of the specified opening and repeat airflow face velocity
measurements/calculations as described above. Record the average airflow face velocity at the 50%
opening position.
9.3.2.9 Reduce the sash position to 25% of the specified opening and repeat airflow face velocity
measurements/calculations as described above. Record the average airflow face velocity at the 25%
opening position.
9.3.2.10 It should be noted that the total fume hood exhaust volume is NOT equal to the average
37
NEBB FHT PROCEDURAL STANDARDS
SECTION 9
AIRFLOW VELOCITY
TEST PROCEDURES
airflow face velocity being captured through the sash opening. Additionally, air will enter the hood
under the airfoil and may enter the hood through leakage and other openings.
9.3.3 TEST PROCEDURES (Response Time)
There are two acceptable methods to perform and measure VAV Speed of Response Tests: exhaust
duct airflow velocity or hood plenum airflow velocity. Determine the baseline and response conditions
by either of the following methods:
a. Exhaust duct airflow velocity method: Place the sensing device in a stable (non-turbulent
airflow) location of the exhaust duct,
or
b. Fume hood plenum airflow velocity method: Place sensing device in the fume hood plenum
behind the baffle panel in a stable (non-turbulent airflow) location. See Appendix B for
proper locations.
9.3.3.1 Measure the velocity at the operating sash opening to establish a baseline condition.
9.3.3.2 The Response Time Test involves 3 cycles of opening and closing the sash position from full
closed to the operating sash opening. When changing the sash position, use a smooth continuous
motion and move the sash at a rate of approximately 1.5 feet per second (0.45 m/s).
9.3.3.3 Close the sash completely, start velocity measurements recording and leave closed for 30
seconds. Open the sash to the operating sash opening for 60 seconds. Close the sash for 30
seconds. Open the sash to the operating opening for 60 seconds. Close the sash for 30 seconds.
Open the sash to the operating sash opening for 60 seconds and then stop velocity measurement
recording.
9.3.3.4 Measure and record velocity readings at one second intervals.
9.3.3.5 Measure, record and report the VAV Speed of Response Time to first obtain a velocity equal
to 90% of baseline condition for each iteration.
9.3.3.6 Measure, record and report the VAV Time to Steady State to maintain the velocity to within
±10% of baseline condition for each iteration.
9.3.3.7 Perform measurements for all 3 cycles. The procedure stated above applies to either vertical
or horizontal sash configurations. For fume hoods with combination sash configurations, the procedure
shall be performed both in the vertical and in the horizontal sash opening positions.
9.3.3.8 The repeatability of the results shall be analyzed for all three cycles by determining the relative
range of the response times for all three cycles. The relative range is the comparison of the lowest
response time and highest response time to the average response time. It shall be calculated as
follows:
9.3.3.8.1
Low Value of Range: Divide the minimum response time by the average response time.
38
NEBB FHT PROCEDURAL STANDARDS
9.3.3.8.2
9.3.3.8.3
9.3.3.8.4
SECTION 9
AIRFLOW VELOCITY
TEST PROCEDURES
High Value of Range: Divide the maximum response time by the average response time.
Relative Range: The range from the Low Value of Range to the High Value of Range.
Repeatability: The difference from the Low Value of Range to the High Value of Range
All of the above values shall be reported as percentages. See Appendix E for an example of the test
reporting.
9.3.4 ACCEPTANCE
The acceptance criteria for the speed of response time, time to steady state, and the repeatability shall
be as specified in the contract documents or as agreed to between the Owner / Buyer and the NEBB
Certified FHT Firm.
9.3.5 REPORTING
See Section 5.2.9 for reporting requirements.
39
NEBB FHT PROCEDURAL STANDARDS
40
SECTION 9
AIRFLOW VELOCITY
TEST PROCEDURES
SECTION 10 AIRFLOW
VISUALIZATION TESTS
PROCEDURES
10.1 INTRODUCTION
The purpose of these tests is to visually verify the fume hood airflow patterns. As with the Airflow Velocity
Tests described in Section 9, all mechanical ventilation systems serving the space shall be functional and
operating in the normal mode. This includes, but is not limited to, the supply, return and exhaust systems,
air terminal boxes, air outlets, air inlets, etc. serving the space. The automatic control equipment and
building automation systems shall be operational, calibrated, and commissioned. The TAB work shall be
completed.
Additionally, the operation of the space shall replicate the normal mode of operation during the tests. This
would include that all SOP’s are followed relating to safety, hood operation, quantity of equipment in
operation during the tests, etc.
Finally, the Airflow Velocity Tests should be completed prior to performing the Airflow Visualization Tests
and the Airflow Visualization Tests should be completed prior to performing the Tracer Gas Containment
Tests.
10.2 AIRFLOW VISUALIZATION TESTS – LOCAL CHALLENGE
The purpose of the test is to provide a visual indication of the fume hood’s capture performance with a
small smoke challenge. Care should be taken to insure that the testing personnel’s presence and
procedures will not influence the results of this test or that the challenge selected does not produce the
flow quantity, volume or momentum such that the visual observations might be affected by the challenge.
The Local Challenge Test should be performed prior to performing the Large Volume Challenge Test.
Coordinate disabling the local fire alarm system when performing this test. Care should be taken to
compensate for smoke discharge velocity and exposure outside of the fume hood.
The smoke source shall be as specified in the contract documents or as agreed to between the Owner
and the NEBB Certified FHT Firm. In all cases, the NEBB FHT Firm shall have written approval from the
Owner, Designer, or AHJ before using a particular smoke source.
10.2.1 INSTRUMENTS AND EQUIPMENT
10.2.1.1 Provide a small smoke source that meet the requirements of Table 4-1.
10.2.1.2 Provide a video recorder that meets the requirements of Table 4-1. (Optional)
10.2.2 TEST PROCEDURES
10.2.2.1 Set the sash position to operating condition as determined by the Airflow Face Velocity Test.
10.2.2.2 Place the smoke source outside the fume hood and under the airfoil. Move along the entire
length of the opening. Verify that the smoke is drawn into the hood, properly exhausted and not
41
NEBB FHT PROCEDURAL STANDARDS
SECTION 10
AIRFLOW VISUALIZATION
TEST PROCEDURES
entrained in a vortex at the top of the hood.
10.2.2.3 Position the smoke source along the sides and bottom of the hood in the sash plane opening.
For combination, or horizontal sash fume hoods, pass smoke source along the inside edge of all
openings. Verify that the smoke is drawn into the hood and exhausted properly.
10.2.2.4 Place the smoke source 6” (152 mm) inside the hood along the bottom of, and parallel to, the
sash. Move along the entire length of the sash bottom. Verify that the smoke is contained within the
hood and properly exhausted.
10.2.2.5 Move the smoke source so that it traverses the entire work surface and around internal
equipment when applicable. Verify that the smoke is contained within the hood and properly exhausted.
10.2.2.6 Place the smoke source outside the fume hood and determine effects of room and HVAC
system conditions by observing the smoke patterns.
10.2.2.7 Place smoke source in cavity above the hood opening and observe the smoke roll inside the
hood.
10.2.2.8 For VAV system fume hoods, close all sashes and traverse the smoke source around the sash
perimeter, under the airfoil and at the bypass intake above the sash. Verify that air is not escaping the
hood around the sash perimeter and all smoke is drawn into the hood under the airfoil and at the bypass
intake.
10.2.3 ACCEPTANCE
Smoke shall be contained within the fume hood under all test procedures. If the smoke escapes the
fume hood under any of the above test procedures, the hood fails and shall be so noted in the report.
The NEBB Certified FHT Firm shall immediately notify the Owner / Buyer in writing that a hood has
failed.
10.2.4 REPORTING
See Section 5.2.10 for reporting requirements.
10.3 AIRFLOW VISUALIZATION TEST – LARGE VOLUME CHALLENGE
The Large Volume Challenge Test SHOULD NOT be performed if the hood failed the Local
Challenge Test. The purpose of the Large Volume Challenge Test is to provide a visual indication of the
fume hood’s capture performance when a large scale challenge is introduced. The test procedures for
the Large Volume Challenge Test are similar to the Local Challenge Test. Coordinate disabling the local
fire alarm system when performing this test. Care should be taken to compensate for smoke
discharge velocity and exposure outside of the fume hood.
The smoke source shall be as specified in the contract documents or as agreed to between the Owner
and the NEBB Certified FHT Firm. In all cases, the NEBB FHT Firm shall have written approval from the
Owner, Designer, or AHJ before using a particular smoke source.
10.3.1 INSTRUMENTS AND EQUIPMENT
10.3.1.1 Provide a large smoke source that meets the requirements of Table 4-1.
42
NEBB FHT PROCEDURAL STANDARDS
SECTION 10
AIRFLOW VISUALIZATION
TEST PROCEDURES
10.3.1.2 Provide a video recorder that meets the requirements of Table 4-1. (Optional)
10.3.2 TEST PROCEDURES
10.3.2.1 Set the sash position to operating condition as determined by the Airflow Face Velocity Test.
10.3.2.2 Place the smoke source outside the fume hood and under the airfoil. Move along the entire
length of the opening. Verify that the smoke is drawn into the hood, properly exhausted and not
entrained in a vortex at the top of the hood.
10.3.2.3 Discharge the smoke source as close to the sash plane as practical for containment and
maximum observation time. Position the smoke source along the sides and bottom of the hood. For
combination, or horizontal sash fume hoods, pass smoke source along the inside edge of all openings.
Verify that the smoke is drawn into the hood and exhausted properly.
10.3.2.4 Discharge the smoke source as close to the sash plane as practical for containment and
maximum observation time. Place the smoke source inside the hood along the bottom of, and parallel
to, the sash. Verify that the smoke is contained within the hood and properly exhausted.
10.3.2.5 Move the smoke source so that it traverses the entire work surface and around internal
equipment when applicable. Verify that the smoke is contained within the hood and properly exhausted.
10.3.2.6 Place the smoke source outside the fume hood and determine effects of room and HVAC
system conditions by observing the smoke patterns.
10.3.2.7 Place smoke source in cavity above the hood opening and observe the smoke roll inside the
hood.
10.3.2.8 For VAV system fume hoods, place the smoke source within the fume hood and close all
sashes. Flood the interior of the fume hood with the smoke source and verify that the smoke is
contained within the hood and exhausted properly.
10.3.2.8 Observe the smoke patterns for containment tests from the side of the hood face.
10.3.3 ACCEPTANCE
Smoke shall be contained within the fume hood under all test procedures. If the smoke escapes the
fume hood under any of the above test procedures, the hood fails and shall be so noted in the report.
The NEBB Certified FHT Firm shall immediately notify the Owner / Buyer in writing that a hood has
failed.
10.3.4 REPORTING
See Section 5.2.11 for reporting requirements.
43
NEBB FHT PROCEDURAL STANDARDS
SECTION 10
AIRFLOW VISUALIZATION
TEST PROCEDURES
44
SECTION 11 TRACER GAS
CONTAINMENT TESTS
PROCEDURES
11.1 INTRODUCTION
The purpose of these tests is to verify the fume hood’s containment performance. As with the Airflow
Velocity Tests described in Section 9 and the Airflow Visualization Tests described in Section 10, all
mechanical ventilation systems serving the space shall be functional and operating in the normal mode.
This includes, but is not limited to, the supply, return and exhaust systems, air terminal boxes, air outlets,
air inlets, etc. serving the space. The automatic control equipment and building automation systems shall
be operational, calibrated, and commissioned. The TAB work shall be completed.
Additionally, the operation of the space shall replicate the normal mode of operation during the tests. This
would include that all SOP’s are followed relating to safety, hood operation, quantity of equipment in
operation during the tests, etc.
A Room Layout Drawing shall be prepared for each tested item. The drawing shall identify, but not limited
to, the following:
a.
b.
c.
d.
Walls
Doors
Fume hood(s),
Other environmental enclosures such as bio-safety cabinets, laminar flow hoods,
canopy hoods, etc.
e. Location and airflow pattern of all air supply, return and exhaust grilles, registers and diffusers.
Finally, Tracer Gas Containment Tests should only be performed after the Airflow Velocity Tests and the
Airflow Visualization Tests are successfully completed.
11.2 TRACER GAS CONTAINMENT TESTS
When performing the Tracer Gas Containment Tests, the NEBB Certified FHT Firm must establish the
test setup (AM, AI, AU). See Section 8 for descriptions. Fume hood size and sash configuration will also
affect the number of sample locations for these tests.
The most widely utilized tracer gas is sulfur hexaflouride (SF6). Other gases may be utilized as the tracer
gas, but they should be of the same approximate molecular weight and stability as that of sulfur
hexaflouride
The tracer gas shall be as specified in the contract documents or as agreed to between the Owner and
the NEBB Certified FHT Firm. In all cases, the NEBB FHT Firm shall have written approval from the
Owner, Designer, or AHJ before using a particular tracer gas.
45
NEBB FHT PROCEDURAL STANDARDS
SECTION 11
TRACER GAS CONTAINMENT
TEST PROCEDURES
Perform a field calibration of the detection instrument and the ejector system in accordance with
manufacturer’s recommendations prior to performing each tracer gas test session. Perform a field
verification of the detection instrument calibration at the end of the test session using a known
concentration of tracer gas. It is recommended that the detection instrument be periodically subjected to
a low level concentration of tracer gas as the test session progresses to verify instrument functionality. If
the verification test fails, re-calibrate the detection instrument and perform the tracer gas test session
again. A test session shall be defined as any time the detection instrument is powered up and down.
While the test procedures identified below are based on using SF6, there may be some slight variances
based on the use of another tracer gas.
11.2.1 INSTRUMENTS AND EQUIPMENT
11.2.1.1 Provide a detection instrument w/calibrator that meets the requirements of Table 4-1.
11.2.1.2 Provide an ejector system w/calibrator or bubble gauge that meets the requirements of Table 41.
11.2.1.3 Provide a tracer gas that meets the requirements of Table 4-1 and Section 11.2
11.2.1.4 Provide a mannequin that meets the requirements of Table 4-1.
11.2.1.5 Provide a data logger that meets the requirements of Table 4-1.
11.2.1.6 Provide a video recorder that meets the requirements of Table 4-1. (Optional)
11.2.2 TEST PROCEDURES (Static Mode)
11.2.2.1 Set the sash position to operating condition as determined by the Airflow Face Velocity Test. If
the test is performed at conditions other than full open, it is suggested that this test should also be
performed at full open sash position to determine the effect of misuse or conditions during equipment
setup or loading.
11.2.2.2 Perform a background measurement test of the room concentration levels at a representative
location. If during the test a steady increase in the sample readings is noted, perform background
measurements to assist in determining the source.
11.2.2.3 All dimensions identified below in locating the ejector system are meant to indicate the near
edge of the ejector base. The ejector system shall be located 6” (152 mm) behind the sash for all test
locations. This places the detection sensor / sensing tube 9” (229 mm) from the ejector. If this location
cannot be accomplished due to equipment placement or other obstructions, move the ejector system and
move the detection sensor / sensing tube to a suitable location that will maintain the 9” (229 mm) spacing,
or as close as possible to the 9” (229 mm) spacing. Use the following method to identify the ejector
system locations:
a. Vertical Sash: Three (3) locations are required for fume hood 8’ (2.4 m) or less: 12” (304 mm)
from the left wall, 12” (304 mm) from the right wall and in the center. Four (4) locations are
required for fume hoods greater than 8’ (2.4 m): 12” (304 mm) from the left wall, 12” (304 mm)
left of center line, 12” (304 mm) right of center line and 12” (304 mm) from the right wall.
46
NEBB FHT PROCEDURAL STANDARDS
SECTION 11
TRACER GAS CONTAINMENT
TEST PROCEDURES
b. Horizontal Sash: Centerline of each design and/or maximum opening space as previously
determined in the Airflow Velocity Tests.
c. Combination Sash: Locations shall be determined by both the vertical and horizontal sash
configurations described above.
11.2.2.4 Place the ejector system inside the fume hood at the first location.
11.2.2.5 The mannequin shall be directly in front of the ejector system at each test location. The
detection sensor/sensing tube shall be located in the breathing zone of the mannequin at a distance of 9”
(229 mm) from the near edge of the ejector system typically 3” (76 mm) from the face of the sash and 22”
(559 mm) above the work surface.
11.2.2.6 Release the tracer gas at the rate as specified in the contract documents or as agreed to
between the Owner and the NEBB Certified FHT Firm. If a release rate has not been specified, then the
release rate shall be 4 l/m. Wait 30 seconds before taking samples.
11.2.2.7 Record samples every second for a duration of 5 minutes.
11.2.2.8 Proceed to the next test location and repeat procedure.
11.2.2.9 Report all of the individual readings, the average and the peak concentration for each test
location.
11.2.2.10 The performance rating is the highest average of the test locations.
Performance Rating shall be reported as follows:
The Static Mode
AM yyy
AI yyy
AU yyy
Where yyy is the highest average concentration of the test locations in ppm. See Appendix E for an
example of the test reporting.
11.2.3 ACCEPTANCE (Static Mode)
Acceptance ratings for the Static Mode Tests shall be as specified in the contract documents or as agreed
to between the Owner / Buyer and the NEBB Certified FHT Firm. Where acceptance ratings have not
been defined, the average concentration shall be no greater than those specified in ANSI Z9.5 and shall
be as follows:
0.050 ppm for AM at a release rate of 4 l/m
0.100 ppm for AI at a release rate of 4 l/m
0.100 ppm for AU at a release rate of 4 l/m
Results should also be evaluated by Owner’s / Buyer’s properly trained personnel for acceptable rating.
11.2.4 REPORTING (Static Mode)
See Section 5.2.12 for reporting requirements.
47
NEBB FHT PROCEDURAL STANDARDS
SECTION 11
TRACER GAS CONTAINMENT
TEST PROCEDURES
11.2.5 TEST PROCEDURES (Sash Movement Effect)
11.2.5.1 All dimensions identified below in locating the ejector system are meant to indicate the near
edge of the ejector base. The ejector system shall be located 6” (152 mm) behind the sash and shall be
located in the center of the fume hood. This places the detection sensor / sensing tube 9” (229 mm) from
the ejector. If this location cannot be accomplished due to equipment placement or other obstructions,
move the ejector system and the detection sensor / sensing tube to a suitable location that will maintain
the 9” (228 mm) spacing.
11.2.5.2 The mannequin shall be directly in front of the ejector system at each test location. The
detection sensor/sensing tube shall be located in the breathing zone of the mannequin at a distance of 9”
(229 mm) from the near edge of the ejector system typically 3” (76 mm) from the face of the sash and 22”
(559 mm) above the work surface.
11.2.5.3 Release the tracer gas at the rate as specified in the contract documents or as agreed to
between the Owner and the NEBB Certified FHT Firm. If a release rate has not been specified, then the
release rate shall be 4 l/m.
11.2.5.4 The Sash Movement Effect Test involves 3 cycles of opening and closing the sash position from
full closed to operating position. When changing the sash position, use a smooth continuous motion and
move the sash at a rate of approximately 1.0 to 1.5 feet per second (0.30 to 0.45 m/s).
11.2.5.5 Close the sash completely, start recording and leave closed for 60 seconds. Open the sash to
the operating position for 60 seconds. Close the sash for 60 seconds. Open the sash to the operating
position for 60 seconds. Close the sash for 60 seconds. Open the sash to the operating position for 60
seconds and then stop recording.
11.2.5.6 For combination hoods, testing shall be performed in both the vertical and in the horizontal
positions.
11.2.5.7 Record samples every second continuously for all three cycles.
11.2.5.8 Calculate the 45 second rolling average for each cycle. Record the maximum rolling average
associated with each opening of the sash. The Sash Movement Effect Performance Rating shall be
reported as follows:
SME – AM yyy
SME – AI yyy
SME – AU yyy
Where yyy is the maximum rolling average tracer gas concentration in ppm. See Appendix E for an
example of the calculations and the reporting.
11.2.6 ACCEPTANCE
Acceptance ratings for the Sash Movement Effect (SME) may be as specified in the contract documents
or as agreed to between the owner / buyer and the NEBB Certified FHT Firm. Report the performance
rating as indicated above.
Results should also be evaluated by Owner’s/Buyer’s properly trained personnel for acceptable ratings.
48
NEBB FHT PROCEDURAL STANDARDS
SECTION 11
TRACER GAS CONTAINMENT
TEST PROCEDURES
11.2.7 REPORTING
See Section 5.2.12 for reporting requirements.
11.2.8 TEST PROCEDURES (Perimeter Scan)
11.2.8.1 Open the sash to the same operating position utilized when performing the Static Mode Test as
described above.
11.2.8.2 Place the ejector system in the center of the of the work surface (center from left to right and
center from the sash plane to the baffle).
11.2.8.3 Remove the mannequin from the front of the fume hood. Remove the detection sensor/sensing
tube from the mannequin.
11.2.8.4 Release the gas at the rate as specified in the contract documents or as agreed to between the
Owner and the NEBB Certified FHT Firm. If a release rate has not been specified, then the release rate
shall be 4 l/m. Release the gas for 30 seconds prior to scanning.
11.2.8.5 While holding the detection sensor/sensing tube in your hand, scan the perimeter of the sash
opening and below the airfoil at a rate of not more than 3”/sec (76 mm/sec). Detection sensor/sensing
tube shall be passed 1” (25 mm) from the outside surface of the fume hood.
11.2.8.6 Record any measurable leakage and report the location and magnitude. See Appendix E for an
example of the test reporting.
11.2.9 ACCEPTANCE
Acceptance ratings for the Perimeter Scan may be as specified in the contract documents or as agreed to
between the Owner/Buyer and the NEBB Certified FHT Firm. Report the results as indicated above.
Results should also be evaluated by Owner’s/Buyer’s properly trained personnel for acceptable results.
11.2.10 REPORTING
See Section 5.2.12 for reporting requirements.
49
NEBB FHT PROCEDURAL STANDARDS
SECTION 11
TRACER GAS CONTAINMENT
TEST PROCEDURES
50
SECTION 12 OPTIONAL TESTS
AND PROCEDURES
12.1 INTRODUCTION
As previously stated in Section 8.3, the NEBB Fume Hood Performance Testing program is flexible. The
required scope of work shall be as specified in the contract documents or as agreed to between the
Owner/Buyer and the NEBB Certified FHT Firm and may differ from the testing requirements of this NEBB
Procedural Standard and / or ASHRAE Standard 110.
The NEBB Certified FHT Firm shall be capable of performing any of the fume hood performance tests
identified in the NEBB Procedural Standards for Fume Hood Performance Testing. The NEBB Certified
FHT Firm shall also be capable of performing a variation of these tests. This may include, but is not
limited to, portions of these tests, or tests that may stipulate different procedures and/or reporting
requirements.
The NEBB Certified FHT Firm is capable of providing a certified report that identifies the measured data
and the results of the tests.
12.2 OTHER TESTS AND PROCEDURES
When reporting the results of non-standard tests, the NEBB Certified FHT Firm shall clearly indicate in
the report the unique procedures followed for the test.
12.3 SUPPLEMENTARY TESTS AND PROCEDURES
In addition to variations of standard tests, a stated scope of work may also require the NEBB Certified
FHT Firm to perform other supplementary tests such as:
a)
b)
c)
d)
e)
Room Airflow Velocity Tests
Temperature/Humidity Uniformity Tests
Sound and Vibration Level Tests
Cross Draft Condition Tests
Other Tests
If any other tests are required, the test instrumentation, test procedures, acceptance criteria and reporting
shall be specified in the contract documents or as agreed to between the Owner/Buyer and the NEBB
Certified FHT Firm.
12.3.1 ROOM AIRFLOW VELOCITY TESTS
Room airflow velocity tests may be performed to determine the velocity pattern(s) of the air being supplied
to a space, or the air being returned or exhausted from a space. This test may be utilized as a diagnostic
tool when trouble shooting a project where containment enclosures such as fume hoods are not
performing adequately due to poor air distribution layout.
51
NEBB FHT PROCEDURAL STANDARDS
SECTION 12
OPTIONAL TESTS
AND PROCEDURES
When performing this test, the NEBB Certified FHT Firm should follow the procedures and requirements
as identified in the current edition of the NEBB Procedural Standards for Certified Testing of Cleanrooms.
12.3.2 TEMPERATURE/HUMIDITY UNIFORMITY TESTS
Temperature and/or humidity uniformity tests may be performed to determine the temperature and/or
humidity gradient that may exist in a space. This test may be utilized as a diagnostic tool when trouble
shooting a project where excessive temperature and/or humidity differentials may exist and could effect
the results of the process being conducted in a containment enclosure.
When performing this test, the NEBB Certified FHT Firm should follow the procedures and requirements
as identified in the current edition of the NEBB Procedural Standards for Certified Testing of Cleanrooms.
12.3.3 SOUND AND VIBRATION LEVEL TESTS
Sound level tests may be performed to determine the overall sound pressure levels in an operating
space. Vibration level tests may be performed to determine vibration magnitude levels of rotating
equipment that may be in, or adjacent to an operating space. These tests may be performed as an
adjunct test to normal fume hood performance testing or may be used as a diagnostic tool when trouble
shooting a project where sound and/or vibration levels may be excessive.
When performing these tests, the NEBB Certified FHT Firm should follow the procedures and
requirements as identified in the current edition of the NEBB Procedural Standards for Measurement of
Sound and Vibration.
12.3.4 CROSS DRAFT CONDITION TESTS
Cross draft condition tests may be performed to document the performance of the fume hood’s
containment ability when external draft conditions are present. Laboratory/Cleanroom designers and the
installing contractors should be aware of the impact of the items such as:
a.
b.
c.
d.
The location of the fume hood in the space
Location of doors whose opening and closing may cause a draft condition
The location of overhead supply, return and exhaust air devices may affect the draft conditions
The relative adjacency of other containment devices
The NEBB Certified FHT Firm is required to prepare a layout drawing of the space prior to testing the
fume hood tracer gas tests (See Section 11.1) that identifies these components. The fume hood
performance may be acceptable to the somewhat static conditions described in Sections 9, 10 and 11
while these standard tests are performed and yet may not provide adequate containment when subjected
to unusual, or artificially, created conditions. These draft tests may include testing the performance in
concert with a cross-draft, down-draft, or back-draft condition. Additionally, a test designed to simulate
the action of personnel walking across the face of the hood during its operation may also display an
unsafe condition. The purpose of all of these draft tests is to make the owner/ operators aware of these
influences on a fume hood’s performance.
The scope of work, the acceptance criteria and the reporting shall be in accordance with the requirements
of the contract documents or as agreed to between the Owner/Buyer and the NEBB Certified FHT Firm.
52
NEBB FHT PROCEDURAL STANDARDS
SECTION 12
OPTIONAL TESTS
AND PROCEDURES
12.3.5 OTHER TESTS
Other tests may also be performed and reported by the NEBB Certified FHT Firm based on the
requirements of the contract documents or as agreed to between the Owner/Buyer and the NEBB
Certified FHT Firm.
53
NEBB FHT PROCEDURAL STANDARDS
SECTION 12
OPTIONAL TESTS
AND PROCEDURES
54
APPENDIX A SAMPLE FHT
SPECIFICATION
(This recommended FHT specification is available from www.nebb.org)
NEBB recommends that these FHT Specifications be referenced as related documents in other
appropriate sections of the project specifications.
SECTION 15990 – FUME HOOD PERFORMANCE TESTING
PART 1 - GENERAL
1.1 RELATED DOCUMENTS
Drawings and general provisions of the Contract, including General and Supplementary Conditions
and Division 1 Specification Sections, apply to this Section.
This Section includes the performance testing of fume hoods.
1.2 DEFINITIONS
Acceptance Criteria: The measured value(s) or range(s) which determine if the results of the test pass
or fail.
Accuracy: The capability of an instrument to indicate the true value of a measured quantity.
AHJ: The local governing Authority Having Jurisdiction over the installation.
Air Supply Fixtures: Devices or openings through which air flows into the laboratory room. For the
purpose of this standard all accessories, connecting duct adapters, or other mounting airways shall be
considered part of the supply fixture and reported as a unit or an assembly. Some specific supply
fixtures are defined as follows:
grille: a louvered or perforated face over an opening
register: a combination grille and damper assembly
diffuser: an outlet designed to mix supply air and room air and to distribute it in varying directions
perforated ceiling: a ceiling with perforated panels used to distribute the air uniformly throughout
the ceiling or a portion of the ceiling. Filter pads may be used to achieve a similar result.
Auxiliary Air: Unconditioned or partially conditioned supply or supplemental air delivered to a
laboratory at the laboratory fume hood to reduce room air consumption.
Calibrate: The act of comparing an instrument of unknown accuracy with a standard of known
accuracy to detect, correlate, report, or eliminate by adjustment any variation in the accuracy of the
tested instrument.
Control Level: The average measured concentration of tracer gas, in parts of tracer gas per million
parts of air by volume (ppm), that is not exceeded at the hood face with a 4.0 Lpm release rate.
I
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
Deficiency: Any circumstance or operation that affects the measurement results as compared to the
design criteria required by the contract documents.
Design Sash Opening: The position of the sash at which the design team assumes that the fume
hood will be operating.
Face Velocity: The average velocity of air moving perpendicular to the hood face, usually expressed
in feet per minute (fpm) or meters per second (m/s).
Fume Hood (sometimes referred to as a laboratory hood): A box-like structure enclosing a source
of potential air contamination, normally with one open or partially open side, into which air is moved
for the purpose of containing and exhausting air contaminants. A fume hood is generally used for
bench-scale laboratory operations but does not necessarily involve the use of a bench or table.
Fume Hood System: An arrangement consisting of a fume hood, its adjacent room environment,
and the air exhaust equipment, such as blowers and ductwork, required to make the hood operable.
Function: For the purposes of this NEBB Standard, function refers to the specific type of data
measurement specified in Section 4, Standards for Instrumentation and Calibration.
High Value of Range: The maximum response time divided by the average response time of the
VAV Response Time Test. Value is expressed as a percentage.
Hood Face: The plane of minimum area at the front portion of a laboratory fume hood through which
air enters when the sash(es) is (are) fully opened, usually in the same plane as the sash for a hood
with a vertical sash. For a hood with horizontal sash(es) or a combination sash, the hood face is
usually the plane passing through the midpoint between the inner and outer sashes.
Lazy Airflow: Airflow within the hood is described as lazy when smoke remains on the work surface
without smoothly flowing to the back baffle.
LPM: Liters per minutes.
Low Value of Range: The minimum response time divided by the average response time of the VAV
Response Time Test. Value is expressed as a percentage.
May: Used to indicate a course of action that is permissible as determined by the NEBB Certified
FHT Firm.
Maximum Sash Opening: The position of the sash at which the fume hood has the largest opening.
N/A: Not Available, Not Applicable, or Not Accessible. The simple notation “N/A” without definition is
not allowed.
NEBB Certified FHT Firm: A NEBB Certified FHT Firm is a firm that has met and maintains all the
requirements of the National Environmental Balancing Bureau for firm certification in Fume Hood
Performance Testing and is currently certified by NEBB. A NEBB Certified FHT Firm shall employ at
least one NEBB Certified FHT Professional in a full time management position.
II
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
NEBB Certified FHT Report: The data presented in a NEBB Certified FHT Report accurately
represents system measurements obtained in accordance with the current edition of the NEBB
Procedural Standards for Fume Hood Performance Testing. A NEBB Certified FHT Report does not
necessarily guarantee that systems measured conform to the design requirements or stated
guidelines. The report is an accurate representation of the measured results only.
NEBB Certified FHT Professional: A NEBB Certified FHT Professional is a full time employee of
the firm in a management position who has successfully passed the professional level written and
practical qualification examinations and maintains the Ceretified Professional re-certification
requirements of NEBB.
Operating Sash Opening: The position of the sash at which the fume hood user places the sash
while working at the face of the fume hood. The operating sash opening should take into
consideration all of the procedures to be conducted in the fume hood. There may be more than one
operating sash opening.
Performance Rating: Rating definition of the Static Mode Test portion of the Tracer Gas Tests. It is
comprised of a series of letters and numbers consisting of the letters AM, AI, or AU, and three-digit
number:
AM yyy
AI yyy
AU yyy
Where:
AM indicates the test setup is "As Manufactured,"
AI indicates the test setup is "As Installed,"
AU indicates the test setup is "As Used,"
yyy indicates the control level of tracer gas established by the test in ppm.
As an example: A test rating of AU 0.500 would indicate that the fume hood controls the
leakage into the laboratory to 0.500 ppm at the mannequin's sensing point with a tracer gas
release rate of 4.0 Lpm.
Positional Sash Movement Effect Control Level: The maximum 45-second moving average of the
tracer gas concentration observed during a series of sash movement tests at one ejector and
mannequin position.
Positional Control Level: The average tracer gas concentration at a position during a test.
Precision: The ability of an instrument to produce repeatable readings of the same quantity under
the same conditions. The precision of an instrument refers to its ability to produce a tightly grouped
set of values around the mean value of the measured quantity.
PPM: Parts per million.
Procedure: The approach to and execution of a sequence of work operations to yield a repeatable
and defined result.
Range: The upper and lower limits of an instrument’s ability to measure the value of a quantity for
which the instrument is calibrated.
III
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
Relative Range: The range from the Low Value of Range to the High Value of Range. Reported as
percentages.
Release Rate: The rate of release, in actual liters (litres) per minute (Lpm), of tracer gas during a
hood test.
Repeatability: The difference from the Low Value of Range to the High Value of Range. Reported as
a percentage.
Resolution: The smallest change in a measured variable that an instrument can detect.
Reverse Flow: Airflow within the hood when smoke released in the hood moves forward toward the
front of the hood. This term does not apply to the forward motion of the roll inside the hood that
occurs in the upper cavity of the hood above the hood opening or to the cyclonic motion that occurs
behind a closed horizontal sash.
Roll: The rotation of air, commonly referred to as vortex, in the upper cavity of the hood. The roll is
induced by the momentum of the air entering the hood through the hood opening.
Sash Movement Effect: The maximum of the positional sash movement effects for all the positions
tested on a particular hood.
Sash Movement Effect Performance Rating: Rating definition of the Sash Movement Effect Test
portion of the Tracer Gas Tests. It is comprised of a series of letters and numbers consisting of the
letters SME-AM, SME-AI, or SME-AU, and three-digit number:
SME-AM yyy
SME-AI yyy
SME-AU yyy
Where:
SME means "sash movement effect,"
AM indicates the test setup was "As Manufactured,"
AI indicates the test setup was "As Installed,"
AU indicates the test setup was "As Used,"
yyy equals the sash movement effect, in ppm.
For example: A test rating of SME-AI 10.0, indicates the fume hood was tested in the “AsInstalled” test setup and that the maximum 45-second rolling average concentration of tracer
gas measured during a sash movement test was 10.0 ppm with a tracer gas release rate of
4.0 Lpm .
Shall: The term is used to indicate mandatory requirements that must be followed in order for the
project to become a NEBB certified project. Work must conform to these standards and procedures
and no deviation is permitted. Note: In the event unique circumstances prevent a required action from
being fulfilled, a notation shall be included in the FHT report explaining the reason that the
requirement was not completed. For example, such notation could be one of the following:
Not Available, Not Applicable, or Not Accessible. The simple notation “N/A” without definition is not
allowed.
IV
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
Should: The term is used to indicate that a certain course of action is preferred but not necessarily
required.
Specified Rating: The hood performance rating as specified, proposed, or guaranteed either in the
purchase of the hood or in the design and construction of the laboratory, or both.
Standard: A required qualification, action, or result for FHT work.
Standard Operating Procedure: An internal policy prepared by the each FHT firm and / or prepared
by the Owner/Buyer. Procedures are written to provide guidance, direction, and step-by-step details
relating to issues such as safety, testing protocols, acceptance criteria, etc. NEBB FHT Firm SOP’s
shall be utilized in an absence of SOP’s prepared by the Owner.
Test Sash Opening: The position or positions of the sash at which the fume hood is tested.
Test Setup (Test Setup Mode): Defines the condition of the fume hood being tested. There are
three distinct conditions that the fume hood may be tested:
As-Manufactured (AM): With this test setup, the fume hood is tested at the manufacturer’s
facility or under conditions that would replicate those conditions. The hood and work surface
shall be void of all process equipment, apparatus and chemicals.
As-Installed (AI): With this test setup, the actual fume hood is tested in its installed, operating
condition. All supply, exhaust and return air systems are installed, operable and under control.
The hood and work surface shall be void of all process equipment, apparatus and chemicals.
As-Used (AU): This test setup is the same as the As-Installed setup except the hood is being
utilized for actual process work. Experiment equipment, chemicals and processes are being
carried out inside the hood while the fume hood performance testing is being performed. This
means that all normal operating equipment within the hood shall be activated and operational
including items such as all heat and vapor producing appliances, physical obstructions, etc.
Testing: The use of specialized and calibrated instruments to measure fluid quantities, temperatures,
pressures, rotational speeds, electrical characteristics, velocities, and sound and vibration levels,
Testing, Adjusting, and Balancing (TAB): A systematic process or service applied to heating,
ventilating and air-conditioning (HVAC) systems and other environmental systems to achieve and
document air and hydronic flow rates. The standards and procedures for providing these services are
addressed in the current edition of the NEBB “PROCEDURAL STANDARDS FOR THE TESTING,
ADJUSTING AND BALANCING OF ENVIRONMENTAL SYSTEMS.”
VAV Speed of Response: The time, measured from the first movement of the sash, for the VAV
system to restore the slot velocity or airflow to 90 percent of the average steady-state value.
VAV Time to Steady State: The time, measured from the first movement of the sash, for the VAV
system restore and maintain the average slot velocity of airflow between 90 and 110 percent of the
average steady-state value.
Work Surface: The surface that the fume hood sets on.
V
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
1.3 FHT FIRM QUALIFICATIONS
The FHT Firm shall be NEBB Certified in Fume Hood Performance Testing. The individual
conducting the fume performance testing shall be a NEBB Certified FHT Professional.
1.4 FHT FIRM SUBMITTALS
1.4.1 Qualification Data: When requested, submit 2 copies of evidence that the FHT firm and
this
Project's FHT team members meet the qualifications specified in Sub-section 1.3
FHT Firm Qualifications.
1.4.2 FHT Agenda: When requested, submit 2 copies of the FHT Agenda. Include a complete
set of report forms intended for use on this Project.
1.4.3 Certified FHT Reports: Submit a final FHT report in accordance with the current edition of
the NEBB Procedural Standards for Fume Hood Performance Testing.
1.5 QUALITY ASSURANCE
1.5.1 The NEBB Certified FHT Firm shall submit 2 copies of the firm's NEBB FHT Certification.
1.5.2 When requested, the NEBB Certified FHT Firm shall provide the NEBB Certificate of
Conformance Certification.
1.5.3 FHT Report Forms: Prepare report forms in accordance with the requirements from the
current edition of the NEBB Procedural Standards for Fume Hood Performance Testing.
1.5.4 Instrumentation Calibration: Calibration of instruments shall be in accordance with the
current edition of the NEBB Procedural Standards for Fume Hood Performance Testing.
1.6 CONSTRUCTION TEAM RESPONSIBILITY TO FHT AGENCY
1.6.1 Provide the NEBB Certified FHT Firm with a conformed set of contract documents
(drawings, specifications, and approved submittals), including all current approved change
orders/contract modifications.
1.6.2 Develop a project schedule with the input of the NEBB Certified FHT Firm that
coordinates the work of other disciplines and provides adequate time in the construction
process to allow successful completion of the FHT work.
1.6.3 Notify the NEBB Certified FHT Firm of schedule changes.
1.6.4 Ensure that the building enclosure is complete, including but not limited to, all structural
components, windows and doors installed, door hardware complete, ceilings complete, stair,
elevator and mechanical shafts complete, roof systems complete, all plenums sealed, etc.
1.6.5 Complete the installation of permanent electrical power systems serving the HVAC
equipment and systems. Such systems shall be properly installed in accordance with all
applicable codes to ensure the safety of all construction personnel.
1.6.6 Complete the installation of all HVAC equipment and systems to ensure safe operation.
VI
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
1.6.7 Perform the startup of all HVAC equipment and systems in accordance with the
manufacturer’s recommendations.
1.6.8 Complete installation, programming (including design parameters and graphics),
calibration, and startup of all building control systems.
1.6.9 Verify that the building control system provider has commissioned and documented their
work before the FHT work begins.
1.6.10 Require that the building control system firm provide access to hardware and software,
or onsite technical support required to assist the FHT effort. The hardware and software or the
onsite technical support shall be provided at no cost to the NEBB Certified FHT Firm.
1.6.11 Furnish and install all drive changes as required.
1.6.12 Complete all TAB work prior to performing FHT work.
1.7 FHT INSTRUMENTATION AND EQUIPMENT
The FHT Firm shall provide all necessary instrumentation, equipment and appurtenances required to
perform the fume hood performance testing. All instrumentation, equipment and appurtenances shall
be as indicated in the current edition of the NEBB Procedural Standards for Fume Hood Performance
Testing.
PART 2 - PRODUCTS (Not Applicable)
PART 3 – EXECUTION
3.1 EXAMINATION
Examine the Contract Documents to become familiar with Project requirements and to discover
conditions in systems' designs that may preclude proper FHT of systems and equipment. Contract
Documents are defined in the General and Supplementary Conditions of the Contract. Report
deficiencies discovered.
The NEBB Certified FHT Firm shall verify that the TAB work is complete and shall review the
completed TAB Report prior to performing any fume hood tests.
3.2 GENERAL PROCEDURES FOR FUME HOOD PERFORMANCE TESTING
Perform hood testing on each fume hood indicated to be tested according to the procedures
contained in the current edition of the NEBB Procedural Fume Hood Performance Testing and this
section.
3.3 TEST SETUP MODE
All fume hoods shall be tested in the select one (As-Manufactured, As-Installed or As-Used) test setup
mode.
3.4 DESIGN SASH OPENING
(The design professional must select the appropriate design sash opening for each hood and each
type of hood i.e. horizontal sash, vertical sash, or combination sash. The following may be used as a
guide in selecting the design sash opening:
VII
NEBB FHT PROCEDURAL STANDARDS
Vertical Sash
Horizontal Sash
Combination Sash
APPENDIX A
SAMPLE FHT SPECIFICATION
18” above the work surface
One sash fully open, all other sashes closed(3 sash), or two sashes fully
open and two sashes fully closed( 4 sash)
One sash fully open to 18” above the work surface and all other sashes
closed.
If the design professional is unsure about selecting the appropriate sash design sash opening, the
owner should be consulted. It is imperative to specify the design sash opening, as the fume hood
performance tests are based on this sash position.)
The design sash opening shall be _(insert height)____” above the work surface for vertical sash fume
hoods, or
The design sash opening shall be _(insert number of sashes)_____sashes open for horizontal sash
fume hoods, or
The design sash opening shall be __(insert height)____” above the work surface and ___(insert
number of sashes)_____ open for combination sash fume hoods.
3.5
AIRFLOW VELOCITY TESTS: Constant Air Volume (CAV) Fume Hood
3.5.1
Test Procedures: Airflow Face Velocity Tests
3.5.1.1 Set hood to the design opening sash position or as agreed to by the Owner / Buyer.
Measure the area of the opening. The area shall be determined as follows:
Height shall be based on the dimension from the bottom most part of the sash to the
work surface located in a straight plane directly beneath the sash for vertical sashes, or
the opening between horizontal tracks on horizontal sashes.
Width: Width shall be based on the interior dimensions of the design sash opening.
3.5.1.2 Determine a grid pattern of equal areas by dividing the opening into horizontal and
vertical dimensions. Each equal area grid location shall be a maximum of one (1) square
foot (0.093 m²) with no dimension larger than 13” (330 mm).
3.5.1.3 Place the instrument on the equipment stand and locate the instrument in the center
of each grid location in the plane of the sash opening and normal to the plane. All personnel
should stand clear of the hood so as not to affect the airflow.
3.5.1.4 Measure and record the airflow face velocities at the center of each grid location.
Each grid location shall have a minimum of 20 samples taken at one second intervals.
Average the 20 samples at each location to determine the airflow face velocity at each grid
location.
3.5.1.5 The hood airflow face velocity is determined by averaging the airflow face velocity
from each grid location. Report the hood average airflow face velocity and the highest and
lowest grid location average.
3.5.1.6 If the actual average airflow face velocity as determined above does not meet the
acceptance criteria as Section 3.5.2, remedial work, if required, is NOT part of the fume hood
testing scope of work. If authorized, the remedial work could be performed by the NEBB
Certified FHT Firm as an additional service.
VIII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
3.5.1.7 For reference and safety purposes, the fume hood airflow face velocity should also
be determined at a full open sash position. The procedure to be followed shall be as
previously indicated above.
3.5.1.8 It should be noted that the total fume hood exhaust volume is NOT equal to the
average airflow face velocity being captured through the sash opening. Additionally, air may
enter the hood through leakage and other openings.
3.5.2 Acceptance Criteria:
The acceptance criteria for CAV airflow face velocity shall be select one:
100 fpm ±10 fpm
As directed by the Owner / Buyer
Define acceptance criteria if other than 100 fpm
3.5.3 Reporting Requirements
The following shall be included in the final report:
a.
b.
c.
d.
e.
f.
g.
h.
3.6
Technician Name
Date of test
Sash Configuration
Design Opening Sash Position (Height and Width)
Average Airflow Velocity at each grid location (fpm) (m/s)
Hood average Airflow Face Velocity (fpm) (m/s)
Test instrumentation
Acceptance Criteria
AIRFLOW VELOCITY TESTS: Variable Air Volume (VAV) Fume Hood
3.6.1 Test Procedures: Airflow Face Velocity Tests
3.6.1.1 Set hood to the design opening sash position or as agreed to by the Owner / Buyer.
Measure the area of the opening. The area shall be determined as follows:
Height shall be based on the dimension from the bottom most part of the sash to the
work surface located in a straight plane directly beneath the sash for vertical sashes,
or the opening between horizontal tracks on horizontal sashes.
Width: Width shall be based on the interior dimensions of the design sash opening.
3.6.1.2 Determine a grid pattern of equal areas by dividing the opening into horizontal and
vertical dimensions. Each equal area grid location shall be a maximum of one (1) square
foot (0.093 m²) with no dimension larger than 13” (330 mm).
3.6.1.3 Place the instrument on the equipment stand and locate the instrument in the center
of each grid location in the plane of the sash opening and normal to the plane. All personnel
should stand clear of the hood so as not to affect the airflow.
3.6.1.4 Measure and record the airflow face velocities at the center of each grid location.
Each grid location shall have a minimum of 20 samples taken at one second intervals.
Average the 20 samples at each location to determine the airflow face velocity at each grid
location.
IX
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
3.6.1.5 The hood airflow face velocity is determined by averaging the airflow face velocity
from each grid location. Report the hood average airflow face velocity and the highest and
lowest grid location average.
3.6.1.6 If the actual average airflow face velocity as determined above does not meet the
acceptance criteria as Section 3.4.2, remedial work, if required, is NOT part of the fume hood
testing scope of work. If authorized, the remedial work could be performed by the NEBB
Certified FHT Firm as an additional service.
3.6.1.7 For reference and safety purposes, the fume hood airflow face velocity should also
be determined at a full open sash position. The procedure to be followed shall be as
previously indicated above.
3.6.1.8 Reduce the sash position to 50% of the specified opening and repeat airflow face
velocity measurements / calculations as described above. Record the average airflow face
velocity at the 50% opening position.
3.6.1.9 Reduce the sash position to 25% of the specified opening and repeat airflow face
velocity measurements / calculations as described above. Record the average airflow face
velocity at the 25% opening position.
3.6.1.10 It should be noted that the total fume hood exhaust volume is NOT equal to the
average airflow face velocity being captured through the sash opening. Additionally, air may
enter the hood through leakage and other openings.
3.6.2
Test Procedures: Response Test
3.6.2.1 There are two acceptable methods to perform and measure response time:
exhaust duct airflow velocity or hood plenum airflow velocity. Determine the baseline and
response conditions by either of the following methods:
a. Exhaust duct airflow velocity method: Place the sensing device in a stable (nonturbulent airflow) location of the exhaust duct, or
b. Fume hood plenum airflow velocity method: Place sensing device in the fume hood
plenum behind the baffle panel.
3.6.2.2 Measure the velocity at the full sash opening to establish a baseline condition.
3.6.2.3 The Response Time Test involves 3 cycles of opening and closing the sash position
from full closed to full open. When changing the sash position, use a smooth continuous
motion and move the sash at a rate of approximately 1.5 feet per second (0.45 m/s).
3.6.2.4 Close the sash completely, start velocity measurements recording and leave closed
for 30 seconds. Open the sash to full opening for 60 seconds. Close the sash for 30
seconds. Open the sash to full opening for 60 seconds. Close the sash for 30 seconds.
Open the sash to full opening for 60 seconds. Close the sash for 30 seconds and stop
velocity measurements recording.
3.6.2.5 Measure and record velocity readings at one second intervals.
X
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
3.6.2.6 Measure, record and report the speed of response to first obtain a velocity equal to
90% of baseline condition for each iteration.
3.6.2.7 Measure, record and report the time to maintain the velocity to within ±10% of
baseline condition for each iteration.
3.6.2.8 Perform measurements for all 3 cycles. The procedure stated above applies to
either vertical or horizontal sash configurations. For fume hoods with combination sash
configurations, the procedure shall be performed both in the vertical and in the horizontal
sash opening positions.
3.6.2.9 The repeatability of the results should be analyzed for all three cycles by
determining the relative range of the response times for all three cycles. The relative range
is the comparison of the lowest response time and highest response time to the average
response time. It may be calculated as follows:
3.2.6.9.1
3.2.6.9.2
3.2.6.9.3
3.2.6.9.4
Low Value of Range: Divide the minimum response time by the average
response time.
High Value of Range: Divide the maximum response time by the average
response time.
Relative Range: The range from the Low Value of Range to the High Value
of Range.
Repeatability: The difference from the Low Value of Range to the High Value
of Range
All of the above values shall be reported as percentages.
3.6.3
Acceptance Criteria:
3.6.3.1
The acceptance criteria for VAV airflow face velocity shall be select one:
100 fpm ±10 fpm
As directed by the Owner / Buyer
Define acceptance criteria if other than 100 fpm
3.6.3.2
The acceptance criteria for average speed of response, individual speed of
responses, individual times to maintain, Low Value of Range, High Value of
Range, Relative Range and Repeatability shall be select one:
As directed by the Owner / Buyer
Define criteria for all of the reporting criteria
3.6.4 Reporting Requirements
The following shall be included in the final report:
a.
b.
c.
d.
e.
f.
g.
Technician Name
Date of test
Sash Configuration
Design Opening Sash Position (Height and Width)
Average Airflow Velocity at each grid location (fpm) (m/s)
Hood average Airflow Face Velocity (fpm) (m/s)
Test results reported at 25%, 50% and 100% of specified conditions
XI
NEBB FHT PROCEDURAL STANDARDS
h.
i.
j.
k.
l.
m.
n.
o.
p.
APPENDIX A
SAMPLE FHT SPECIFICATION
Speed of Response (in seconds) (3 cycles)
Low Value of Range (in percentage)
High Value of Range (in percentage)
Relative Range (in percentage)
Repeatability (in percentage)
Time to Maintain (in seconds) (3 cycles)
Test Method (exhaust airflow velocity method or fume hood plenum airflow
velocity method)
Test instrumentation
Acceptance Criteria
3.7 AIRFLOW VISUALIZATION TESTS: Local Challenge
The purpose of the Local Challenge Test is to provide a visual indication of the fume hood’s capture
performance when a small scale challenge is introduced. Coordinate disabling the local fire alarm
system when performing this test. Care should be taken to compensate for smoke discharge
velocity and exposure outside of the fume hood.
3.7.1 Test Procedures
3.7.1.1 Set the sash position to operating condition as determined by the Airflow Face
Velocity Test.
3.7.1.2 Place the smoke source outside the fume hood and under the airfoil. Move along
the entire length of the opening. Verify that the smoke is drawn into the hood, properly
exhausted and not entrained in a vortex at the top of the hood.
3.7.1.3 Position the smoke source along the sides and bottom of the hood in the sash plane
opening. For combination, or horizontal sash fume hoods, pass smoke source along the
inside edge of all openings. Verify that the smoke is drawn into the hood and exhausted
properly.
3.7.1.4 Place the smoke source 6” (152 mm) inside the hood along the bottom of, and
parallel to, the sash. Move along the entire length of the sash bottom. Verify that the smoke
is contained within the hood and properly exhausted.
3.7.1.5 Move the smoke source so that it traverses the entire work surface and around
internal equipment when applicable. Verify that the smoke is contained within the hood and
properly exhausted.
3.7.1.6 Place the smoke source outside the fume hood and determine effects of room and
HVAC system conditions by observing the smoke patterns.
3.7.1.7 Place smoke source in cavity above the hood opening and observe the smoke roll
inside the hood.
3.7.2 Acceptance Criteria
Smoke shall be contained within the fume hood under all test procedures. If the smoke escapes
the fume hood under any of the above test procedures, the hood fails and shall be so noted in
the report. The NEBB Certified FHT Firm shall immediately notify the Owner / Buyer in writing
that the fume hood has failed.
3.7.3
Reporting Requirements
XII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
The following shall be included in the final report:
a.
Technician Name
b.
Date of test
c.
Test State
d.
Sash Configuration
e.
Sash Opening Height and Width
f.
Challenge Medium Used
g.
Narrative description of actual visual test results including Statement of
Pass/Fail
h.
Test instrumentation
i.
Acceptance Criteria
3.8 AIRFLOW VISUALIZATION TESTS: Large Volume Generation
The Large Volume Challenge Test SHOULD NOT be performed if the hood failed the Local
Challenge Test. The purpose of the Large Volume Challenge Test is to provide a visual indication of the
fume hood’s capture performance when a large scale challenge is introduced. The test procedures for
the Large Volume Challenge Test are similar to the Local Challenge Test. Coordinate disabling the local
fire alarm system when performing this test.
Care should be taken to compensate for smoke discharge velocity and exposure outside of the
fume hood.
3.8.1 Test Procedures
3.8.1.1 Set the sash position to operating condition as determined by the Airflow Face Velocity
Test.
3.8.1.2 Place the smoke source outside the fume hood and under the airfoil. Move along the
entire length of the opening. Verify that the smoke is drawn into the hood, properly exhausted
and not entrained in a vortex at the top of the hood.
3.8.1.3 Discharge the smoke source as close to the sash plane as practical for containment
and maximum observation time. Position the smoke source along the sides and bottom of the
hood. For combination, or horizontal sash fume hoods, pass smoke source along the inside
edge of all openings. Verify that the smoke is drawn into the hood and exhausted properly.
3.8.1.4 Discharge the smoke source as close to the sash plane as practical for containment
and maximum observation time. Place the smoke source inside the hood along the bottom of,
and parallel to, the sash. Verify that the smoke is contained within the hood and properly
exhausted.
3.8.1.5 Move the smoke source so that it traverses the entire work surface and around
internal equipment when applicable. Verify that the smoke is contained within the hood and
properly exhausted.
3.8.1.6 Place the smoke source outside the fume hood and determine effects of room and
HVAC system conditions by observing the smoke patterns.
3.8.1.7 Place smoke source in cavity above the hood opening and observe the smoke roll
inside the hood.
3.8.1.8 Try to observe smoke patterns for containment tests from the side of the hood face.
XIII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
3.8.2 Acceptance Criteria
Smoke shall be contained within the fume hood under all test procedures. If the smoke escapes
the fume hood under any of the above test procedures, the hood fails and shall be so noted in
the report. The NEBB Certified FHT Firm shall immediately notify the Owner / Buyer in writing
that the fume hood has failed.
3.8.3 Reporting Requirements
The following shall be included in the final report:
a.
b.
c.
d.
e.
f.
g.
h.
i.
3.9
Technician Name
Date of test
Test State
Sash Configuration
Sash Opening Height and Width
Challenge Medium Used
Narrative description of actual visual test results including Statement of
Pass/Fail
Test instrumentation
Acceptance Criteria
TRACER GAS CONTAINMENT TESTS: Static Mode
3.9.1 Test Procedures
3.9.1.1 Set the sash position to operating condition as determined by the Airflow Face
Velocity Test. If the test is performed at conditions other than full open, it is suggested that this
test should also be performed at full open sash position to determine the effect of misuse or
condition during equipment setup or loading.
3.9.1.2 Perform a background measurement test of the room concentration levels at a
representative location. If during the test a steady increase in the sample readings is noted,
perform background measurements to assist in determining the source.
3.9.1.3 All dimensions identified below in locating the ejector system are meant to indicate
the near edge of the ejector base. The ejector system shall be located 6” (152 mm) behind
the sash for all test locations. This places the detection sensor / sensing tube 9” (229 mm) from
the ejector. If this location cannot be accomplished due to equipment placement or other
obstructions, move the ejector system and move the detection sensor / sensing tube to a
suitable location that will maintain the 9” (229 mm) spacing, or as close as possible to the 9”
(229 mm) spacing. Use the following method to identify the ejector system locations:
a. Vertical Sash: Three (3) locations are required for fume hood 8’ (2.4 m) or less:
12” (304 mm) from the left wall, 12” (304 mm) from the right wall and in the center.
Four (4) locations are required for fume hoods greater than 8’ (2.4 m): 12” (304 mm)
from the left wall, 12” (304 mm) left of center line, 12” (304 mm) right of center line and
12” (304 mm) from the right wall.
b. Horizontal Sash: Centerline of each maximum opening space as previously
determined in the Airflow Velocity Tests.
c. Combination Sash: Locations shall be determined by both the vertical and
horizontal sash configurations described above.
3.9.1.4
Place the ejector system inside the fume hood at the first location.
XIV
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
3.9.1.5
The mannequin shall be directly in front of the ejector system at each test location.
The detection sensor / sensing tube shall be located in the breathing zone of the mannequin at
a distance of 9” (229 mm) from the near edge of the ejector system typically 3” (76 mm) from
the face of the sash and 22” (558 mm) above the work surface.
3.9.1.6
Release the tracer gas at the rate as specified in the contract documents or as
agreed to between the Owner and the NEBB Certified FHT Firm. If a release rate has not
been specified, then the release rate shall be 4 l/m. Wait 30 seconds before taking samples.
3.9.1.7
Record samples every second for a duration of 5 minutes.
3.9.1.8
Proceed to the next test location and repeat procedure.
3.9.1.9
Report all of the individual readings, the average and the peak concentration for
each test location.
3.9.1.10 The performance rating is the highest average of the test locations. The Static
Mode Performance Rating shall be reported as follows:
AM yyy
AI yyy
AU yyy
Where yyy is the highest average concentration of the test locations in ppm.
3.9.2 Acceptance Criteria
Acceptance ratings for the Static Mode Tests shall be as directed by the Owner / Buyer. Where
acceptance ratings have not been defined, the average concentration shall be no greater than
those specified in ANSI Z9.5 and shall be as follows:
0.05 ppm for AM at a release rate of 4 l/m
0.10 ppm for AI at a release rate of 4 l/m
0.10 ppm for AU at a release rate of 4 l/m
Results will be evaluated by Owner’s / Buyer’s properly trained personnel for acceptable rating.
3.9.3 Reporting Requirements
The following shall be included in the final report:
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
Technician Name
Date of test
Test State
Sash Configuration
Sash Opening Height and Width
Room Layout Drawing
Graphical display of each test
Tracer Gas Release Rate
Test Instrumentation
Report individual readings, the average and peak at each sample location
Report the Performance Rating and compare to the Acceptance Rating. Tests
results that exceed acceptance ratings shall be noted in the report.
XV
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
3.10 TRACER GAS CONTAINMENT TESTS: Sash Movement Effect
3.10.1 Test Procedures
3.10.1.1 All dimensions identified below in locating the ejector system are meant to indicate
the near edge of the ejector base. The ejector system shall be located 6” (152 mm) behind
the sash and shall be located in the center of the fume hood. This places the detection
sensor / sensing tube 9” (228 mm) from the ejector. If this location cannot be accomplished
due to equipment placement or other obstructions, move the ejector system and the detection
sensor / sensing tube to a suitable location that will maintain the 9” (228 mm) spacing.
3.10.1.2 The mannequin shall be directly in front of the ejector system at each test location.
The detection sensor / sensing tube shall be located in the breathing zone of the mannequin
at a distance of 9” (228 mm) from the near edge of the ejector system typically 3” (76 mm)
from the face of the sash and 22” (558 mm) above the work surface.
3.10.1.3 Release the tracer gas at the rate as specified in the contract documents or as
agreed to between the Owner and the NEBB Certified FHT Firm. If a release rate has not
been specified, then the release rate shall be 4 l/m.
3.10.1.4 Start with the sash in the closed position for 60 seconds. Open the sash to the same
operating position utilized when performing the Static Test as described above. The sash
shall remain open for 60 seconds. Close the sash for 60 seconds. Repeat the process for
two additional cycles.
3.10.1.5 The sash should be opened and closed with a smooth motion at a rate of 1.0 to 1.5
feet per second (0.30 to 0.45 m/s).
3.10.1.6 For combination hoods, testing shall be performed in both the vertical and in the
horizontal positions.
3.10.1.7 Record samples every second continuously for all three cycles.
3.10.1.8 Calculate the 45 second rolling average for each cycle. Record the maximum rolling
average associated with each opening of the sash. The Sash Movement Effect Performance
Rating shall be reported as follows:
SME – AM yyy
SME – AI yyy
SME – AU yyy
Where yyy is the maximum rolling average tracer gas concentration in ppm.
3.10.2 Acceptance Criteria
Acceptance ratings for the Sash Movement Effect (SME) shall be as directed by the owner /
buyer. Report the performance rating as indicated above.
Results will be evaluated by Owner’s/Buyer’s properly trained personnel for acceptable ratings
3.10.3 Reporting Requirements
The following shall be included in the final report:
XVI
NEBB FHT PROCEDURAL STANDARDS
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
k.
l.
m.
APPENDIX A
SAMPLE FHT SPECIFICATION
Technician Name
Date of test
Time of test
Test State
Sash Configuration
Sash Opening Height and Width
Room Layout Drawing
Graphical display of each test
Tracer Gas Release Rate
Test Instrumentation
Record the maximum 45 second rolling average associated with each opening of
the sash.
Report the Sash Movement Performance Rating.
If Acceptance Rating has been defined, test results that exceed acceptance
rating shall be noted in the report.
3.11 TRACER GAS CONTAINMENT TESTS: Perimeter Scan
3.11.1 Test Procedures
3.11.1.1 Open the sash to the same operating position utilized when performing the Static
Test as described above.
3.11.1.2 Place the ejector system in the center of the fume hood.
3.11.1.3 Remove the mannequin from the front of the fume hood. Remove the detection
sensor / sensing tube from the mannequin.
3.11.1.4 Release the gas at the rate as specified in the contract documents or as agreed to
between the Owner and the NEBB Certified FHT Firm. If a release rate has not been
specified, then the release rate shall be 4 l/m. Release the gas for 30 seconds prior to
scanning.
3.11.1.5 While holding the detection sensor / sensing tube in your hand, scan the perimeter of
the sash opening and below the airfoil at a rate of not more than 3”/sec (76 mm/sec).
Detection sensor / sensing tube shall be passed 1” (25 mm) from the outside surface of the
fume hood.
3.11.1.6 Record any measurable leakage and report the location and magnitude.
3.11.2 Acceptance Criteria
Acceptance ratings for the Perimeter Scan shall be as directed by the Owner / Buyer. Report the
results as indicated above.
Results will be evaluated by Owner’s / Buyer’s properly trained personnel for acceptable results.
3.11.3 Reporting Requirements
The following shall be included in the final report:
a.
b.
c.
d.
Technician Name
Date of test
Time of test
Test State
XVII
NEBB FHT PROCEDURAL STANDARDS
e.
f.
g.
h.
i.
j.
k.
l.
m.
APPENDIX A
SAMPLE FHT SPECIFICATION
Sash Configuration
Sash Opening Height and Width
Room Layout Drawing
Graphical display of each test
Tracer Gas Release Rate
Test Instrumentation
Record any measurable leakage
Report the location and magnitude of the leakage
If Acceptance Rating has been defined, test results that exceed acceptance
rating shall be noted in the report.
3.12 OTHER TESTS
Edit or delete as applicable to project requirements:
In addition to variations of standard tests, a stated scope of work may also require the NEBB Certified
FHT Firm to perform other supplementary tests such as:
a)
b)
c)
d)
e)
Room Airflow Velocity Tests
Temperature/Humidity Uniformity Tests
Sound and Vibration Level Tests
Cross Draft Condition Tests
Other Tests
If these other tests are required, the test instrumentation, test procedures, acceptance criteria and
reporting shall be specified below or as directed by the Owner/Buyer. All costs associated with these
tests are to be included with the scope of work. The tests shall be specified in a similar format as utilized
above.
3.12.1 Test Procedures
3.12.2 Acceptance Criteria
3.12.3 Reporting Requirements
The following is provided in guidance in specifying these other tests:
3.12.2 ROOM AIRFLOW VELOCITY TESTS
Room airflow velocity tests may be performed to determine the velocity pattern(s) of the air being
supplied to a space, or the air being returned or exhausted from a space. This test may be
utilized as a diagnostic tool when trouble shooting a project where containment enclosures such
as fume hoods are not performing adequately due to poor air distribution layout.
When performing this test, the NEBB Certified FHT Firm should follow the procedures and
requirements as identified the current edition of the NEBB Procedural Standards for Certified
Testing of Cleanrooms.
3.12.3 TEMPERATURE/HUMIDITY UNIFORMITY TESTS
Temperature and/or humidity uniformity tests may be performed to determine the temperature
and /or humidity gradient that may exist in a space. This test may be utilized as a diagnostic tool
when trouble shooting a project where excessive temperature and/or humidity differentials may
exist and could effect the results of the process being conducted in a containment enclosure.
XVIII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
When performing this test, the NEBB Certified FHT Firm should follow the procedures and
requirements as identified the current edition of the NEBB Procedural Standards for Certified
Testing of Cleanrooms.
3.12.4 SOUND AND VIBRATION LEVEL TESTS
Sound level tests may be performed to determine the overall sound pressure levels in an
operating space. Vibration level tests may be performed to determine vibration magnitude levels
of rotating equipment that may be in or adjacent to an operating space. These tests may be
performed as an adjunct test to normal fume hood performance testing or may be used as a
diagnostic tool when trouble shooting a project where sound and/or vibration levels may be
excessive.
When performing these tests, the NEBB Certified FHT Firm should follow the procedures and
requirements as identified the current edition of the NEBB Procedural Standards for
Measurement of Sound and Vibration.
3.12.5 CROSS DRAFT CONDITION TESTS
Cross draft condition tests may be performed to document the performance of the fume hood’s
containment ability when external draft conditions are present. Laboratory / Cleanroom designers
and the installing contractors should be aware of the impact of the items such as:
a.
The location of the fume hood in the space.
b.
Location of doors whose opening and closing may cause a draft condition.
c.
The location of overhead supply, return and exhaust air devices may affect the draft
conditions
d.
The relative adjacency of other containment devices.
The NEBB Certified FHT Firm is required to prepare a layout drawing of the space prior to testing
the fume hood tracer gas tests (See Section 11.1) that identifies these components. The fume
hood performance may be acceptable to the somewhat static conditions described in Sections 9,
10 and 11 while these standard tests are performed and yet may not provide adequate
containment when subjected to unusual, or artificially, created conditions. These draft tests may
include testing the performance in concert with a cross-draft, down-draft, or back-draft condition.
Additionally, a test designed to simulate the action of personnel walking across the face of the
hood during its operation may also display an unsafe condition. The purpose of all of these draft
tests is to make the owner / operators aware of these influences on a fume hood’s performance.
The scope of work, the acceptance criteria and the reporting shall be in accordance with the
requirements of the contract documents or as agreed to between the Owner/Buyer and the NEBB
Certified FHT Firm.
3.12.6 OTHER TESTS
Other tests may also be performed and reported by the NEBB Certified FHT Firm based on the
requirements of the contract documents or as agreed to between the Owner/Buyer and the NEBB
Certified FHT Firm.
3.13 FINAL REPORT
The final report shall be in accordance with the requirements of the current edition of the NEBB
Procedural Standards for the Fume Hood Performance Testing.
XIX
NEBB FHT PROCEDURAL STANDARDS
APPENDIX A
SAMPLE FHT SPECIFICATION
XX
APPENDIX B EXAMPLE TEST
ILLUSTRATIONS
The examples and illustrations presented in this appendix are meant to provide guidance in
performing the various Fume Hood Performance Tests.
B.1
FUME HOOD AIRLFOW VELOCITY TESTS – VAV RESPONSE TEST
The purpose of the VAV Response Test is to quantify the time required for the mechanical exhaust
system serving the fume hood to return to its design control point after the sash position has been
changed from a steady state condition. The VAV Response Test involves 3 complete cycles of opening
and closing the sash position from full closed to full open and concurrently measuring the associated
changes in airflow velocity. The sash should be moved using a smooth continuous motion.
There are two components associated with this test:
VAV Speed of Response Time
VAV Time to Steady State
Section 9.3.3 identifies the testing procedure requirements. There are two acceptable methods to
perform and measure response times. Both methods involve the measurement of airflow velocity. The
airflow velocity can be measured either in the exhaust duct or in the fume hood plenum. Figure B-1
illustrates the acceptable sensing device locations which are as follows:
a. Exhaust duct airflow velocity method: Place the sensing device in a stable (non-turbulent
airflow) location of the exhaust duct, or
b. Fume hood plenum airflow velocity method: Place sensing device in the fume hood plenum
behind the baffle panel.
When utilizing the exhaust duct location, the sensing device should be located in a long, straight run of
hard duct approximately 4 to 5 diameters downstream of any offsets, elbows or other obstructions.
Additionally, the sensing device should be located at least 1 to 2 diameters upstream of any offsets,
elbows or other obstructions.
When utilizing the fume hood plenum location, the sensing device should be located in the rear exhaust
plenum through an opening in the interior exhaust baffles. The sensor should be positioned so as to
read flow being exhausted through the top of the hood if directional probe is utilized with a consistent
velocity reading during initial setup procedure.
XXI
NEBB FHT PROCEDURAL STANDARDS
APPENDIX B
EXAMPLE TEST ILLUSTRATIONS
Figure B – 1: VAV Response Test Setups
XXII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX B
EXAMPLE TEST ILLUSTRATIONS
B.2
TRACER GAS CONTAINMENT TESTS
The purpose of the Tracer Gas Containment Tests is to verify the fume hood’s containment
performance. Figure B-2 illustrates the correct spatial arrangement of the mannequin and the ejector
system for the Static Mode Test and the Sash Movement Effect Test.
3”
75mm
HORIZ. SASH
6”
150mm
Figure B – 2: Mannequin and Ejector Position
XXIII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX B
EXAMPLE TEST ILLUSTRATIONS
XXIV
APPENDIX C EJECTOR
SYSTEM SPECIFICATIONS
Figure C – 1: Ejector System (US Units)
Figure C – 2: Ejector System (SI Units)
Figure C – 3: Ejector – General Arrangement (US Units)
Figure C – 4: Ejector – General Arrangement (SI Units)
Figure C – 5: Critical Orifice (US Units)
Figure C – 6: Critical Orifice (SI Units)
XXV
APPENDIX C
EJECTOR SYSTEM SPECIFICATIONS
Figure C – 1: Ejector System (US Units)
NEBB FHT PROCEDURAL STANDARDS
XXVI
APPENDIX C
EJECTOR SYSTEM SPECIFICATIONS
Figure C – 2: Ejector System (SI Units)
NEBB FHT PROCEDURAL STANDARDS
XXVII
APPENDIX C
EJECTOR SYSTEM SPECIFICATIONS
Figure C – 3: Ejector – General Arrangement (US Units)
NEBB FHT PROCEDURAL STANDARDS
XXVIII
APPENDIX C
EJECTOR SYSTEM SPECIFICATIONS
Figure C – 4: Ejector – General Arrangement (SI Units)
NEBB FHT PROCEDURAL STANDARDS
XXIX
APPENDIX C
EJECTOR SYSTEM SPECIFICATIONS
Figure C – 5: Critical Orifice (US Units)
NEBB FHT PROCEDURAL STANDARDS
XXX
APPENDIX C
EJECTOR SYSTEM SPECIFICATIONS
Figure C – 6: Critical Orifice (SI Units)
NEBB FHT PROCEDURAL STANDARDS
XXXI
NEBB FHT PROCEDURAL STANDARDS
APPENDIX C
EJECTOR SYSTEM SPECIFICATIONS
XXXII
APPENDIX D REFERENCES
AND REFERENCED
PUBLICATIONS
A.
Air Movement Control Association International, Inc. (AMCA)
30 West University Drive, Arlington Heights, IL 60004
AMCA Publication 201-2002 , Fan Application Manual
AMCA Publication 203-1990, Field Performance Measurement of Fan Systems
Both publications contain engineering fundamentals of fan application, design and
performance ratings and field measurements.
B.
American Industrial Hygiene Association (AIHA)
2700 Prosperity Avenue, Suite 250, Fairfax, VA 22031
ANSI/AIHA Standard Z9.5-2003, Laboratory Ventilation
Contains information on the recommendations, design, installation, and maintenance of
laboratory ventilation systems.
C.
American Conference of Governmental industrial Hygienists (ACGIH)
Kemper Meadow Drive, Cincinnati, Ohio 45240
ACGIH Publication: Industrial Ventilation, A Manual of Recommended Practice
Contains information on the design and installation of industrial ventilation systems and
exhaust systems and hoods.
D.
American Society of Heating, Air Conditioning and Refrigerating Engineers (ASHRAE)
1791 Tullie Circle Northeast, Atlanta, Georgia 30329
ASHRAE Handbook—HVAC Applications (2007)
Chapter 7—Health Care Facilities
Chapter 14—Laboratory Systems
Chapter 16—Clean Spaces
ANSI/ASHRAE Standard 110, Method of Testing Performance of Laboratory Fume
Hoods
E.
National Environmental Balancing Bureau (NEBB)
8575 Grovemont Circle, Gaithersburg, Maryland 20877-4121
E.1 Environmental Systems Technology
Contains information on HVAC system history and fundamentals, engineering principles,
system design, equipment components and installation, testing and balancing, controls,
acoustics, and an extensive glossary and set of engineering tables and charts.
E.2 Procedural Standards for Testing, Adjusting, and Balancing of Environmental
Systems—2005
A "how-to" set of procedural standards that provide systematic methods for testing,
adjusting, and balancing (TAB) of HVAC systems includes sections on TAB instruments
and calibration, report forms, and sample specification.
E.3 Testing, Adjusting, Balancing Manual for Technicians—1997
A practical field-use manual for balancing technicians designed to be used for reference
and job site application as well as for training balancing crews. This edition includes a
section on mathematics and equations for field use.
XXXIII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX D
REFERENCES AND
REFERENCED PUBLICATIONS
E.4 Procedural Standards for Certified Testing of Cleanrooms—2006
This manual provides an extensive array of information on cleanroom testing, technology
and test procedures. It includes: cleanroom design; cleanroom systems; laboratory and
health facilities; test instruments and test procedures; HEPA filter leak testing; and
particle counts.
E.5 Study Course for Certified Testing of Cleanrooms
A self-study course in cleanrooms and systems including cleanroom testing equipment,
control systems, cleanroom test procedures, system and unit test procedures, and
cleanroom equipment and accessories.
E.6 Procedural Standards for the Measurement of Sound and Vibration—2006
This publication provides background information and step-by-step comprehensive
guidance for obtaining and recording sound and vibration data on HVAC systems. Topics
include: instrumentation, inspection of building construction and conditions, interior and
exterior sound measurement, and vibration measurement procedures. Also covered are
sample specifications and report forms.
E.7 Sound and Vibration Design and Analysis—1994
A concise coverage of sound and vibration as it relates to HVAC systems. Basic
concepts of the science of sound and vibration are covered, plus the most current
information on equipment sound levels, duct element regenerated and sound power and
attenuation, duct breakout and breakin, sound transmission in indoor and outdoor
spaces, and vibration analysis. Includes references and glossary.
E.8 Study Course for Measuring Sound and Vibration—1995
A home study course on measuring sound and vibration, it guides the student in an
orderly sequence, with diagrams, charts and problems to recognize principles and
procedures.
E.9 Procedural Standards for Building Systems Commissioning—1999
A manual providing comprehensive guidance for commissioning building HVAC systems.
The text describes organization, planning, procedures and methods for verifying and
documenting the performance of building systems. Included are a sample specification,
model reporting forms, check sheets and functional test checklists, as well as a
schematic depicting the commissioning process.
G.
National Sanitation Foundation (NSF)
789 N. Dixboro Road, Ann Arbor, Michigan 48106
NSF 49-2005, Class II (Laminar Flow) Biohazard Cabinetry
This document applies to cabinetry designed to minimize hazards inherent in work with
low and moderate risk biological agents and defines tests which must be passed.
H.
National Fire Prevention Association (NFPA)
1 Batterymarch Park, Quincy, Massachusetts 02169
I.
Scientific Equipment and Furniture Association (SEFA)
1205 Franklin Ave., Ste. 320, Garden City, NY 11530
J.
United States of America, Agencies and Departments
US Department of Labor - Occupational Safety & Health Administration
200 Constitution Avenue, NW, Washington, DC 20210
XXXIV
APPENDIX E ENGINEERING
FORMULAS AND EXAMPLES
E.1 HVAC ENGINEERING FORMULA (SI UNITS)
E.1.1 AIR EQUATIONS
A.
V = 1.414 ● (VP/d)½
where
V = Velocity
d=
density, “d” = 3.48 (Pb/T)
B.
V = (1.66 ● VP)½ for Std. air (d = 1.204 kg/m3)
C.
TP = VP + SP
D.
V = VM (d / 1.204)
E.
Airflow Volume (L/s) = 1000 ● Area ● Volume
E.2 HVAC ENGINEERING FORMULA (IP UNITS)
E.2.1 AIR EQUATIONS
A.
V = 1096 • (VP/d)½
where
V = Velocity
d=
density, “d” = 1.325 (Pb/T)
B.
V = 4005 • (VP)½ for Std. air (d = .075 lbs/ft3)
C.
TP = VP + SP
D.
V = VM (d / 0.075)
E.
Airflow Volume (cfm) = Area ● Volume
XXXV
NEBB FHT PROCEDURAL STANDARDS
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
E.3 METRIC EQUIVALENTS
QUANTITY
acceleration
airflow
volumetric flow
rate
area
atmospheric
pressure
distance,
length, or
displacement
lighting
intensity
lighting power
pressure
temperature
velocity
volume
SYMBOL
m/s²
m³/s
L/s
m³/hr
m²
mm²
kPa
Bar
M
M
mm
Lx
lm/m²
Lm
kPa
Pa
°C
m/s
m³
UNIT
meters per second squared
cubic meters per second
liters per second
cubic meters per hour
square meter
square millimeters
kiloPascals
Barometers
meter
meter
millimeter
Lux
Lumens/square meter
Lumen
kiloPascals =1000 Pascals
Pascals
degrees Celsius
meters per second
cubic meters
XXXVI
IP RELATIONSHIP
1 m/s² = 3.281 ft/sec²
1 m³/s = 2118.88 cfm
1 L/s = 2.12 cfm
1 m³/hr = 0.589 cfm
1 m² = 10.76 ft²
1 mm² = 0.0016 in²
101.325 kPa = 29.92 in. Hg = 14.696 psi
1 Bar = 29.92 in. Hg = 14.696 psi
1 m = 3.281 ft.
1 m = 39.37 inches
1 mm = 0.039 inches
1 lx = 0.0929 fc
1 lm/m² = 0.0931 fc
1 Lm = 0.001496 watts
1 kPa = 0.296 in. Hg = 0.145 psi
1 Pa = 0.004015 in.w.g.
°C = (°F – 32)/1.8
1 m/s = 196.9 fpm
1 m³ = 35.31 ft³
NEBB FHT PROCEDURAL STANDARDS
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
E.4 AIR DENSITY CORRECTION FACTORS (SI UNITS)
Altitude (m)
Sea
Level
250
500
750
1000
1250
1500
1750
2000
2500
3000
Barometer (kPa)
101.3
98.3
96.3
93.2
90.2
88.2
85.1
83.1
80.0
76.0
71.9
Air Temp ºC
1.08
1.00
0.91
0.85
0.79
0.74
0.70
0.66
0.62
0.59
0.56
0.54
0.51
0.49
0.47
0.46
0.44
1.22
1.11
1.02
0.96
0.92
0.84
0.77
0.72
0.67
0.62
0.60
0.56
0.53
0.51
0.48
0.44
0.40
1.17
1.07
0.99
0.93
0.88
0.81
0.74
0.70
0.65
0.60
0.57
0.54
0.51
0.49
0.46
0.43
0.39
1.13
1.03
0.95
0.89
0.85
0.78
0.71
0.67
0.62
0.58
0.55
0.52
0.49
0.47
0.45
0.41
0.37
1.09
0.99
0.92
0.86
0.81
0.75
0.69
0.64
0.60
0.56
0.53
0.50
0.47
0.45
0.43
0.39
0.36
1.05
0.95
0.88
0.83
0.78
0.72
0.66
0.62
0.58
0.54
0.51
0.48
0.45
0.44
0.41
0.38
0.35
1.01
0.91
0.85
0.80
0.75
0.69
0.64
0.60
0.56
0.52
0.49
0.46
0.44
0.42
0.40
0.37
0.33
0.97
0.89
0.82
.077
0.73
0.67
0.62
0.58
0.54
0.51
0.48
0.45
0.43
0.41
0.39
0.35
0.32
0.93
0.85
0.79
0.74
0.70
0.65
.060
0.56
0.52
0.49
0.46
0.43
0.41
0.39
0.37
0.34
0.31
0.90
0.82
0.76
0.71
0.68
0.62
0.57
0.54
0.50
.047
0.44
0.42
0.39
0.38
0.35
0.33
0.30
0.87
0.79
0.73
0.69
0.65
0.60
0.55
0.51
0.48
0.45
0.42
0.40
0.38
0.36
0.34
0.32
0.29
0º
20º
50º
75º
100º
125º
150º
175º
200º
225º
250º
275º
300º
325º
350º
375º
400º
Table E-1: Air Density Correction Factors (SI Units) Standard Air Density (Sea Level and 20ºC) = 1.204 kg/m3 at 101.325 kPa
XXXVII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
E.4 AIR DENSITY CORRECTION FACTORS (IP UNITS)
Altitude (ft)
Sea
Level
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Barometer (in. of Hg.)
(in. w.g.)
29.92
407.50
28.86
392.80
27.82
378.60
26.82
365.00
25.84
351.7
24.90
333.90
23.98
326.40
23.09
314.80
22.22
302.10
21.39
291.10
20.58
280.10
1.26
1.15
1.06
1.00
0.95
0.87
0.80
0.75
0.70
0.65
0.62
0.55
0.58
0.53
0.50
0.46
0.42
1.22
1.11
1.02
0.96
0.92
0.84
0.77
0.72
0.67
0.62
0.60
0.56
0.53
0.51
0.48
0.44
0.40
1.17
1.07
0.99
0.93
0.88
0.81
0.74
0.70
0.65
0.60
0.57
0.54
0.51
0.49
0.46
0.43
0.39
1.13
1.03
0.95
0.89
0.85
0.78
0.71
0.67
0.62
0.58
0.55
0.52
0.49
0.47
0.45
0.41
0.37
1.09
0.99
0.92
0.86
0.81
0.75
0.69
0.64
0.60
0.56
0.53
0.50
0.47
0.45
0.43
0.39
0.36
1.05
0.95
0.88
0.83
0.78
0.72
0.66
0.62
0.58
0.54
0.51
0.48
0.45
0.44
0.41
0.38
0.35
1.01
0.91
0.85
0.80
0.75
0.69
0.64
0.60
0.56
0.52
0.49
0.46
0.44
0.42
0.40
0.37
0.33
0.97
0.89
0.82
.077
0.73
0.67
0.62
0.58
0.54
0.51
0.48
0.45
0.43
0.41
0.39
0.35
0.32
0.93
0.85
0.79
0.74
0.70
0.65
.060
0.56
0.52
0.49
0.46
0.43
0.41
0.39
0.37
0.34
0.31
0.90
0.82
0.76
0.71
0.68
0.62
0.57
0.54
0.50
.047
0.44
0.42
0.39
0.38
0.35
0.33
0.30
0.87
0.79
0.73
0.69
0.65
0.60
0.55
0.51
0.48
0.45
0.42
0.40
0.38
0.36
0.34
0.32
0.29
Air Temp ºF
-40º
0º
40º
70º
100º
150º
200º
250º
300º
350º
400º
450º
500º
550º
600º
700º
800º
Table E-2: Air Density Correction Factors (U.S. Units) Standard Air Density (Sea Level and 70ºF) = 0.075 lb/ft3 at 29.92 in. Hg.
XXXVIII
NEBB FHT PROCEDURAL STANDARDS
E.5
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
FHT AIRFLOW FACE VELOCITY
E.5.1 DETERMINING A GRID PATTERN
The purpose of this section is to determine a sample grid pattern for a fume hood airflow face velocity
test. The procedure is identical for both CAV and VAV fume hoods. Sections 9.2.2 and 9.3.2 discuss
the requirements for determining a grid pattern. Both sections state the following requirements:
“Measure the area of the opening. The area shall be determined as follows:
Height: Height shall be based on the dimension from the bottom most part of the sash to the
work surface.
Width: Width shall be based on the interior dimensions of the design sash opening.
Determine a grid pattern of equal areas by dividing the opening into horizontal and vertical dimensions.
Each equal area grid location shall be a maximum of one (1) square foot (0.093 m²) with no dimension
larger than 13” (330 mm).”
A grid pattern is determined in the exact same manner as a duct traverse layout and has the same
purpose: To determine the average airflow velocity. While duct traverse measurements are performed
in order to calculate the airflow volume (m³/s or cfm) flowing inside of a duct, the focus with fume
hoods is strictly to determine the average airflow face velocity.
E.5.2 SAMPLE GRID PATTERN DETERMINATION
The grid pattern layout and calculations presented in this example are intended to serve as a working
illustration of the correct procedures and methods involved in determining the proper grid pattern for all
face velocity measurements for all types of fume hoods.
For this example we have a 6 ft. (1.8 m) fume hood that has a vertical sash configuration. The width of
the interior of the vertical sash is 63” (1.60 m). The design sash opening is 18” (457 mm). You are
required to determine the proper grid pattern. According to NEBB requirements, determine a grid
pattern of equal areas both vertically and horizontally where the maximum area does not exceed one (1)
square foot (0.093 m²) and no dimension exceeds 13” (330 mm).
First determine the number of rows of vertical grids. This can be done by taking the vertical dimension
and dividing by 13”.
# of Vertical Grid Rows = 18” / 13” = 1.38
Consequently, we must have a minimum of 2 vertical grid rows. With two vertical grid rows, the height
of each vertical grid will be equal to:
Vertical Spacing = 18” / 2 = 9”
Since the grids will be 9” apart, the distance from the bottom of the sash to the center of the top grid will
be 4.5 and the distance from the work surface to the center of the bottom grid will also be:
18” = 4.5” + 9” + 4.5”
XXXIX
NEBB FHT PROCEDURAL STANDARDS
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
Second, determine the horizontal grids. Again, no distance can exceed 13” and each grid shall have a
maximum of 1 ft². Based on this criterion, the horizontal spacing can be determined by dividing the
overall width of the sash opening by 13”
Horizontal Columns = 63” / 13” = 4.8
Based on this calculation we must have a minimum of 5 horizontal grids columns. With 5 horizontal grid
columns, the width of each horizontal grid will be equal to:
Horizontal Spacing = 63” / 5 = 12.6”
Since the grids will be 12.6” apart, the distance from the left side of the sash to the center of the first grid
will be 6.3” and the distance to the center of each of the next grids will be on 12.6” centers. Thus, the
overall grid horizontal grid spacing will be:
63” = (6.3” + 12.6” + 12.6” + 12.6” + 12.6” + 6.3”)
Finally, verify that each grid does not exceed 1 ft². Our example resulted with a grid pattern that had 2
vertical rows and 5 columns. Each grid would have an area of 113.4 square inches (9”x12.6” = 113.4
in²), or 0.79 ft² (113.4 /144 = 0.79 ft²). Each grid area does not exceed the 1.00 ft² criteria.
The grid pattern shown below in Figure E.5.2.1. as determined from above shows 2 vertical rows and 5
horizontal columns. Each grid in this example is 9” x 12.6”.
FIGURE E 5.2.1
XL
NEBB FHT PROCEDURAL STANDARDS
E.6
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
FHT MEASURMENT AND REPORTING EXAMPLES
E.6.1 AIRFLOW FACE VELOCITY TEST – VARIABLE AIR VOLUME (VAV) FUME HOOD
As stated in Section 9.3.3 for the Response Test: “The repeatability of the results should be analyzed
for all three cycles by determining the relative range of the response times for all three cycles. The
relative range is the comparison of the lowest response time and highest response time to the average
response time.” For the Response Test, the following information is to be calculated and reported:
•
•
•
•
Low Value of Range
High Value of Range
Relative Range
Repeatability
These values may be calculated as follows:
Average Response Time: Add the response times from each of three cycles and divide by three.
Low Value of Range: Divide the minimum response time by the average response time.
High Value of Range: Divide the maximum response time by the average response time.
Relative Range: State the range from the Low Value of Range to the High Value of Range.
Repeatability: The difference from the Low Value of Range to the High Value of Range
All of the above values shall be reported as percentages.
As an example, the response times for the three cycles are: 4 seconds, 5 seconds and 5 seconds.
The Average Response Time is:
The Low Value of Range is:
The High Value of Range is:
The Relative Range is:
The Repeatability is:
(4 + 5 + 5)/3 = 4.67 seconds.
4 seconds/4.67 seconds = 86%.
5 seconds/4.67 seconds = 107%.
86% - 107%.
21%.
Note: It is appropriate to report the average time to two decimal places and the various ranges and
repeatability values should be rounded off and reported in full percentage points only.
E.6.2 TRACER GAS CONTAINMENT (STATIC MODE)
As stated in Section 11.2.2 for the Static Mode Test, “The performance rating is the highest average of
the test locations. The Static Mode Performance Rating shall be reported as follows:
AM yyy
AI yyy
AU yyy
Where yyy is the highest average concentration of the test locations in ppm.”
The static mode performance rating contains two components; the test setup and the highest average
leak concentration of all the test locations in ppm.
As an example, the static mode test is performed on a 6’ vertical sash fume hood. The fume hood Test
Setup is As-Installed. Since the fume hood is less than 8’, the static mode test must be performed in
XLI
NEBB FHT PROCEDURAL STANDARDS
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
three locations; 12” from the left wall, 12” from the right wall and in the center. Each set of
measurements is averaged and the highest average of the three locations is reported. You have
performed the test for each of the required locations and have calculated the following averages:
Location:
12” from the left wall
12” from the right wall
Center of the fume hood
Average Concentration
0.032 ppm
0.025 ppm
0.081 ppm
The highest average concentration is the center location. Consequently, the static mode test reporting
would be as follows:
AI 0.081
Note that it is appropriate to report results to three decimal places. Additionally, decimal values should
be stated with a zero located in front of the decimal point. This is the manner that metric values are
reported and fume hood test results should also be reported in this manner.
E.6.3 TRACER GAS CONTAINMENT (SASH MOVEMENT EFFECT)
Section 11.2.5 defines the procedures for performing the Sash Movement Effect Test. It states to
“Calculate the 45 second rolling average for each cycle. Record the maximum rolling average
associated with each opening of the sash. The Sash Movement Effect Performance Rating shall be
reported as follows:
SME – AM yyy
SME – AI yyy
SME – AU yyy
Where yyy is the maximum rolling average tracer gas concentration in ppm
The reporting of the Sash Movement Effect Performance Rating is similar to the Static Mode
Performance Rating except that it contains three components; the acronym SME (for Sash Movement
Effect), the test setup and the highest average leak concentration in ppm.
Additionally, the Sash Movement Effect requires a calculation not a simple reporting of averages. The
45-second rolling average must be calculated for each of the three sash movement cycles from fully
closed to fully open. For each cycle, there are 16 individual data sets must be averaged and then “rolled”
into a single value. The procedure is as follows:
As the sash is moved from closed to open, the time must be noted at the beginning of the sash opening.
The 16 individual data sets are as follows:
Data Set Number
1
2
3
15
16
Time Span
1 through 45 Seconds
2 through 46 Seconds
3 through 47 Seconds
15 through 59 Seconds
16 through 60 Seconds
XLII
NEBB FHT PROCEDURAL STANDARDS
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
The first time span would include all of the concentration values for seconds 1 through 45. The second
time span would include all of the concentration values for seconds 2 through 46. The process continues
through the 16th data set which would include the concentration values from second 16 through 60.
The average leak concentration for each of the three opening cycles is calculated and the highest
average is reported as the Sash Movement Effect Performance Rating.
An example will help to illustrate the required calculations and reporting. You are performing the Sash
Movement Effect Test you are ready to begin the test. The test procedures require you release the tracer
gas and close the sash. You should begin data logging the measurements at this time. The sash is to
remain closed for 60 seconds. After 60 seconds, you open the sash to the operating position for 60
seconds. Then, you closed the sash for 60 seconds. You repeated this procedure for 3 complete cycles
from fully closed to the operational sash position. The measurements were continuously data logged for
the entire test. The data measurements are as shown in Table E.6.3.1. and the 45-Second Rolling
Averages have been calculated in Tabled E.6.3.2 below.
Table E.6.3.1 Data Measurements:
Project
Lab Room Number
Fume Hood Number
Test date
Atomic Laboratories
Tested by
101
Joe Smith
101-1
Tracer Gas Concentration (ppm)
1-Jan-09
seconds
closed 1
open 1
close 2
open 2
close 3
open 3
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
start at close
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.651
9.972
8.334
9.924
1.991
0.019
0.017
0.017
0.017
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.812
1.004
8.421
9.682
3.691
2.015
0.062
0.019
0.017
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.812
1.004
8.421
9.682
3.691
2.015
0.062
0.019
0.017
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
XLIIII
NEBB FHT PROCEDURAL STANDARDS
seconds
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
closed 1
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
open 1
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
close 2
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
open 2
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
close 3
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
The 45-Second Rolling Averages have been calculated in Tabled E.6.3.2 below.
XLIV
open 3
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
0.016
NEBB FHT PROCEDURAL STANDARDS
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
Table E.6.3.2 45-Second Rolling Average Values
Time Span
0 – 45 sec
1 – 46
2 – 47
3 – 48
4 – 49
5 – 50
6 – 51
7 – 52
8 – 53
9 – 54
10 – 55
11 – 56
12 – 57
13 – 58
14 – 59
15 – 60
Data Set
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Total
Average
Cycle 1
Open
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.700
0.686
0.465
0.280
0.060
0.016
0.016
0.016
7.839
0.490
Cycle 2
Open
0.584
0.584
0.584
0.584
0.584
0.584
0.584
0.584
Cycle 3
Open
0.584
0.584
0.584
0.584
0.584
0.584
0.584
0.584
0.567
0.545
0.358
0.143
0.062
0.017
0.016
0.016
6.396
0.400
0.567
0.545
0.358
0.143
0.062
0.017
0.016
0.016
6.396
0.400
Again, The Sash Movement Effect (SME) Performance Rating is the open cycle that has the highest 45
second rolling average. From data in Table E.6.3.2, Cycle 1 has an average of 0.490 ppm of the tracer
gas concentration. Based on this data and calculations the Sash Movement Effect Performance Rating
for this fume hood will be: SME-AI 0.490
XLV
NEBB FHT PROCEDURAL STANDARDS
APPENDIX E
ENGINEERING FORMULAS
AND EXAMPLES
E.6.4 TRACER GAS CONTAINMENT (PERIMETER SCAN)
The Perimeter Scan portion of the Tracer Gas Containment Tests also has some unique reporting
requirements. Section 11.2.8 requires that any measurable leakage should be identified in the report
and that the location and magnitude should be identified. Figure E.6.4.1 shows a sample report.
Top of sash, 12” from upper left corner (0.45 ppm)
Bottom of sash 39” from lower right corner (0.39 ppm)
Figure E.6.4.1: Sample Perimeter Scan Report Drawing
XLVI