Legally Binding Document

By the Authority Vested By Part 5 of the United States Code § 552(a) and Part 1 of the Code of Regulations § 51 the attached document has been duly INCORPORATED BY REFERENCE and shall be considered legally binding upon all citizens and residents of the United States of America. HEED THIS NOTICE: Criminal penalties may apply for noncompliance.


Document Name: ACGIH: Industrial Ventilation Manual

CFR Section(s): 42 CFR 52b.12

Standards Body: American Conference of Governmental Industrial


Official Incorporator:


A Manual of Recommended Practice

23rd Edition


American Conference of Governmental Industrial Hygienists 1330 Kemper Meadow Drive Cincinnati, Ohio 45240-1634

Copyright © 1998 by

American Conference of Governmental Industrial Hygienists, Inc.

Previous Editions

Copyright © 1951, 1952, 1954, 1956, 1958, 1960, 1962, 1964, 1966, 1968, 1970, 1972, 1974, 1976, 1978, 1980, 1982, 1984, 1986


Committee on Industrial Ventilation American Conference of Governmental Industrial Hygienists

Ist Edition 1951 2nd Edition 1952 3rd Edition 1954 4th Edition 1956 5th Edition 1958 6th Edition 1960 7th Edition 1962 8th Edition 1964 9th Edition 1966 10th Edition 1968 1 1th Edition 1970 12th Edition 1972

13th Edition 1974 {4th Edition 1976 1 Sth Edition 1978 16th Edition 1980 17th Edition 1982 18th Edition 1984 19th Edition 1986 20th Edition 1988 21st Edition 1992 22nd Edition 1995 23rd Edition Metric —1998

Third Printing

ALL RIGHTS RESERVED. No part of this work covered by the copyright hereon may be reproduced or used in any form or by any means graphic, electronic, or mechanical including photocopying, recording, taping, or information storage and retrieval systems without written permission of the publisher.

Published in the United States of America by American Conference of Governmental Industrial Hygienists, Inc. 1330 Kemper Meadow Drive Cincinnati, Ohio 45240-1634

ISBN: 1-882417-22-4 Printed in the United States


DEDICATION) pA RAS ee 2 oh Phe Oo peaane aie tern BO ak Sl a tehe ds abe cet a meee a Le vil FOREWORD: *. 0 gaa Soh ghee bad Swe we Meth el ee eA Bla Se Se es ten ix ACKNOWLEDGMENTS © 2/6 be4 4-5 d-d0dod Bie Eee NE aes Se i ek SD ee a oo Behe dg xi DEFINITIONS” -bS.w Sh. bw dle ee a eae OE Se oe LEG Gee Ea ae bay PLAS xiii ABBREVIATIONS’: -Srsuech et c's oo bt pean Bond ole ee eae le weg ie Grn aed Baw ee a Re ee XV CHAPTER 1 GENERAL PRINCIPLES OF VENTILATION .......0..0.0202020 0002 eee eee 1-1 Tel. Antroduction:. 2.29 ek ee Be AL Eo ever doe BO ee Soe Sn ge Ae ch ick & 1-2

1.2:4 :Supply:Systems~ 9.2 2\6 @ a. a nee ld Oe an Ga Soe be a ee th be got Bak bux. 1-2

13> SExhaust Systems’ 13 ac2 8 Sata“ te Bn Shwe ofa k Sihurtra te oi ais Pele to toe phe as aoe ans 1-2

4) “Basic Definitions :2 isa sales ek Gem eee Gop hoe Oe Se See eS Be Pe ee PS 1-3

15. -Principles‘of-AinFlOwW® ¢ ..pa4 vo ek ee Ok se ep ea ee ot ee tl he 1-4

1.6 Acceleration of Air and Hood Entry Losses... 2... ee 1-6

7 Duct-Losseés® 2.4 .650 8 doe ee ee A oe es oh an Ree he Gree ge 8 1-7

1.8 | Multiple-Hood Exhaust Systems 2... 2... 2 ee 1-9

1.9 Air Flow Characteristics of Blowing and Exhausting.. 2... 0.0. .2.-000.0.0000004 1-10

References! 2 ods deh Pe 2 le Me Bet £4 ee eb Se Mk es SEE oe Oe 1-10

CHAPTER 2 GENERAL INDUSTRIAL VENTILATION. 2.0.0. 2 2-1 2c TintrOduetion. ia nd ones, aa PR woe arid BOR IE Ses See Nae aS eee 2-2

2.2 Dilution Ventilation Principles . 2... 2... ee 2-2

2.3 Dilution Ventilation for Health 2.2.2... 2. 2-2

2.4 Mixtures—Dilution Ventilation for Health .. 2.0... ee 2-6

2.5 Dilution Ventilation for Fire and Explosion... 2... 2 2. ee 2-7

2.6 Fire Dilution Ventilation for Mixtures... 00 2-8

2.7. ‘Ventilation for Heat Control... 2. 2-8

2.8. Heat Balance and.Exchanige =: & 222s 2 ¥ ad i dai eek ee bee Yaw weed ae wed 2-8

2.9 Adaptive Mechanism of the Body .. 2... 0. ee 2-9

2:10 Acchimatization: »,.. 0-3) 4k Shao ye awn ene! Bae es aad, Peow a a heed tee Gated 2-10

21k * “Acute-Heat Disorders: uence So Melk neh che etek eG Woe ag. lhe 2 ke de 8 2-10

2.12 Assessment of Heat Stress and Heat Strain... 2. ee 2-11

2:13: Worker Protection. 5.4a:.0'6! o.0°S ho Bed ele bra Bara ed oA Mae den end Pe 2-13

2.44 Ventilation:Control:.” 3.008 3. ese aca wk od eb eat Pea. Me eS A ee, & Ge ae 2-13

2.13 “Ventilation Systems’ a. .ogo6 gk kb eye de dese Se Gotan la Mh ia Gay abs 2-13

216° Velocity Cooling. cs end ak eke hl tne Boe bad WON sng ww Pe wo eae 2-15

2:47" Radiant Heat:Control: 18% Sse Soe BAe ey ye i RA wa ea ee E eRe ee Soc 2-15

2.18 Protective Suits for Short Exposures 2.2... 0. ee 2-16

2.19 Respiratory Heat Exchangers .. 2... ee 2-16

2:20. Refrigerated Suits): j3,.2:30 4 4p oe heed a eee deg OED ok Seen ok 2-16

ZIV. SENCIOSUTES. 2: a4cis4G: dre Ye Ase hb tee Ale doe a ea a AG eG OR Ea ee te es 2-16

222 1 ANSUVAION ee 5 ered Sein ees an Bete) ea oe Bee Be Mild Sc Ee ad Rae tele 2-16

References: ste ara len Boe BS eno Rae he ar ee et ace CR Ua aed 2-17

CHAPTER 3 LOCAL EXHAUST HOODS.......0... 00.002. 202 cc ee 3-1 Sb Antroductiony: 6. ee Gwe eo es a ek Ra en Bote Pee A A ee ae sb kG 3-2

3.2 Contaminant Characteristics. 2... 2 ee 3-2

33% “IMOGd Types? "2, ates utr Pe ek te Ee Sree Bale RO Ea ens oa ee A pce ie'ek PAO 3-2

3.4 Hood Design Factors... 2.2... ee 3-2

3:5° - Hood. Losses) os. iu bee eee Pee a Pee o4 6 he eee eee oe Fe 3-15







Industrial Ventilation

3.6 Minimum Duct Velocity .. 2... .0.00 000200022 ee 3-18 3.7 Special Hood Requirements .......0...2. 2020-000 0000 eee 3-18 3.8 Push-Pull Ventilation... .......0020 002000000002 eee ee 3-19 3:9". THOUPrOCeSSES? 2.43 4 ee eee eee ee aie dy ea Re tia eden 3-21

RGPEreNCES 54. he thy a eee Ae eotice et We eel hg, ale lena le Oe een hla) a Ye aes 3-23 AIR: CLEANING: DEVICES 3... 2) s-4.00. ah Goh Sh Sie bal a pewea oa Radek doe WS bors, o 4-1 AA HIMtOdUCHON 20%. eG eo eA heels he ts Sa ee os ee a has Se eS Be 4-2 4.2 Selection of Dust Collection Equipment ...........2.2..2.2.. 020220000000. 4-2 4.3-. \Dust-Gollector Lypes:2-0 3 2s SAS ee EOS EES eae eRe RAN ae Se 4-3 4.4 Additional Aids in Dust Collector Selection... 2... .0..0.0022200 002.0000 ee eee 4-22 45 Control of Mist, Gas, and Vapor Contaminants .............0.0..0 2.000000. 4-22 4.6 Gaseous Contaminant Collectors... 2. 2 2. 4-25 4.7, “WnitiCollectors ase. go % hk doce eee ew ac beh ba ce Roe Mien ee eS 4-25 4.8 Dust Collecting Equipment Cost... 0... 0 ee 4-25 4.9 Selection of Air Filtration Equipment .... 0... .002.0.00200 020200000002. eee 4-28 4.10 Radioactive and High Toxicity Operations... 2... ee 4-33 400) Explosion; Venting: 22%. sie Soke 2 het o SLA GP gee en ted eh a Gea Stet a Bw eS 4-33

References: eck ee Oe See Sy he is & DA eats etl wy Sve eas. 2 4-34 EXHAUST SYSTEM DESIGN PROCEDURE... 2... .0.0-020000 20 ee 5-] Sul. Wntroductonis 4-024 gc & oS eee Bi Pe eG See Pew So 6b Ar ep Pe ce 5-2 5.2: “Preliminary: Steps. 4 je. doe we poe Sie RE wae ee Bae ee ee ee Fs 5-2 533°. sDesigni Procedure ‘on-2 5 sets hie gene eh ths abe aS, os ae debe GOS Golan, DE Sew. Pow gt eee ta 5-2 5:4. Duct-Segment:Calculations!::: ¢ ec..¢-5 8 eee ae a a Re a Ee a ee ee 5-3 5.5 Distribution of AirFlow .. 2... 0.0. 5-4 5:6, cAids:-to: Calculation’: oe 33.c dar sab GN eS etew ale he a A ha eee 5-11 §.7 --Plenum:/Exhaust Systems: ..2.5.9 0205. ue ol A Sch e Bhilai le eae we ee 5-1] 5:8: - “Fan-Pressure:Caloulations ioc... 320s ep. Hoa ee ded en Ge een, aE a eo 5-11 5.9 Corrections for Velocity Changes 2.2... ee 5-12 5/10'.: Sample: System: Design 3:1. et. 0d Agee Pe ee eA A Sk ye Sn eel ys dak 5-13 5.11 Different Duct Material Friction Losses 2... 2... 0.02 2 ee 5-13 5.12 Friction Loss for Non-Circular Ducts. 2... ee 5-13 5.13 Corrections for Non-Standard Density... 0... ee 5-15 5.14: Air Cleaning Equipment: @.. (2s 3 oat Seoul Sod oe He eldest Ra 5-32 Slo sEVaSe: Chun etees ters 8 eee he A ls ed tepals eh a od San dl aig eet rete toute Me Sry 5-32 9:16: “ExhaustS tack Outlets: s, 3. ace te ee a aus, Pca ee ee ee ts et Se a ca, le BEA 5-33 S17 Air Bleed2lnss.4.¢0 22404404 b24 0 baie d ethane 6628 44 Pa gee ve dees 5-35 5.18 Optimum Economic Velocity... 2... 02 5-35 5.19 Construction Guidelines for Local Exhaust Systems... 2... 0.00 2 ee ee $-35

References enc: fist Bi ae eth Gk Ate, needing Bike dea Yoo hiadie Bae he Bo 5-38 PAINS} ii 204-2 ict eet dee ee id 1s hts Bec el ae Ale ht od eo ih dtd ie ee ed ae de Se 6-1 Gil. Introductions (ses see se ceais & Ee ea See en ee ce Be Be eRe oe eA 6-2 6:2. .Basic'Définitions 05.4% 3 fF oe Sa Sebo wei ble ow hoes Eee oho tes Fads 6-2 6:3" Fan Selection: sc; 029 ee dye span d Atle tee ebb aos eb Ge aed Cae Wed a eth aS 6-6 6.4 Fan Installation and Maintenance... 2... 2. 2 ee 6-21

References. sor cis Be dene ali i had a es eR EO oe Ew Se ee is ole 6-25 REPLACEMENT AND RECIRCULATED AIR ........0.0...-.......- As Axe an ete 7-1 7A. -InttoductiOn: 20-2 e.2 ce Pee ee a eo ey eH Mahe deb Re ee eae te de 7-2 7.2.- ‘Replacement Am”. «2 9 200 et ecis: faede Epa ee A ee aa, aoe a eS 7-2 7.3. Replacement Air Distribution. ©... 2. ee 7-4 7:4: Replacement Air Flow Rate-. 3.04.4. 5 2 oe be a eG ee ee ee ed 7-5

75) Room’ Pressure..3: g.3)t.ce 63) hod) egw eS oh alan fle dS A oD

7.6 Environmental Control... 2... 0. ee

7.7 Environmental Control Air Flow Rate... 2... 0. ee

PBS CAM CHANGES (fe se We So hl ee eh ats eo BA eM oe es

7.9 Air Supply Temperatures 2... 2... .. 22.2. 20022 0000.

7.10 Air Supply Vs. Plant Heating Costs... ... le ie 1 es Ee gee ae a Bae 8s

7.11 Replacement Air Heating Equipment ...............00-..2000.

7.12 Cost of Heating Replacement Air... 2... 2. 0020.02020.

7.13. ~Air Consérvation=s: 60 1 bd ated oe how hee eae Bea as as

7.14 Evaluation of Employee Exposure Levels... 2... 0.20.20... 0200-00..

References; 23.325 sed ind Sah ohh ik eR Ste de) ee See a Ware eee

CHAPTER 8 VENTILATION ASPECTS OF INDOOR AIR QUALITY ................ S20 Tntroduction. a. a! 3,464 -44¢o05 bk & Ale ee -3 4S oa RG bie ware &

8.2 Dilution Ventilation for Indoor Air Quality... .......0......-.2.00.

8.3. HVAC Components and System Types... 2... 2... 00... 20000-02002

8.4 HVAC Components, Functions and Malfunctions .............--..

8.5 HVAC Component Survey Outline... 2... 0200.20.20... 00220008

References ioe seasoned on tk de ee ON Sr eaten Pe NL et tae

CHAPTER 9 TESTING OF VENTILATION SYSTEMS ..........-..2..0.02.2 0220004 9:1 Introdtiction® 36/5, Bas ea ek ee BA eo Ae AAAS bs eae ER

9.2 Measurements of Volumetric Flow Rate... 2... eee

9.3 Calibration of Air Measuring Instruments... 2... ....0.0.0-.00004

9.4 Pressure Measurement... 2.2... 2. ee

9.5 Pitot Traverse Method .. 2... 2... ee

9.6 Corrections for Non-Standard Conditions... .........0......00..

9.7 Check-out Procedures 2. 22 ee

References: fas. aoe ate he a ae eal dad haleget.a he Bb ts ee

CHAPTER 10 SPECIFIC OPERATIONS ......0.0..0200 000000 cee eee BIBLIOGRAPHY? © 4a. 824 gc$cdcp tagce: waendth het love eect inal tes Moet, oe SOS Pc Rew APPENDICES) ait dipaccis i Gate Boeraty a tik WA Be Math a ot a ges MN ee ad Ae a de gh Bb

A Threshold Limit Values for Chemical Substances in the Work Environment with Intended Changes for 1996-1997 B Physical Constants/Conversion Factors

INDEX oA eb ey oe a oe ls Shh Gas tebe pa aad hed aie ity antes



This Edition is Dedicated in Memory of KNOWLTON J. CAPLAN, PE, CiH, CSP June 23, 1919 - April 11, 1997

Knowlton J. Caplan, while at the Division of Occupational Health, Michigan Department of Health, supervised the preparation of a field manual on industrial ventilation. That manual became the basis of the first edition of /ndustrial Ventilation in 1951. For the next forty-six years, the Ventila- tion Committee has felt Caplan’s presence as we published the “Vent Manual.” This 23" edition is no different. Although “Cap” has not been an active member of the Committee for the past eleven years, his presence was felt at almost every meeting. Frequently we punctuated discussions with a quota- tion from Cap or a reference to one of his published works. Because of his influence, we proudly dedicate this edition to Knowlton J. Caplan.

During his 50-year career, Cap was a pioneer in the fields of industrial hygiene, industrial ventilation, and air pollution control. He conducted basic research on cyclone and fabric filter dust collectors and holds several patents for these de- vices. As an associate professor in the public health depart- ment of the University of Minnesota, Cap advised numerous Master’s degree students in industrial hygiene, occupational health and air pollution control. He has been an instructor at the industrial ventilation conferences at Michigan State Uni- versity (thirty years) and the University of Washington (ten years). As an author of more than 70 technical papers, he was a frequent presenter at the American Industrial Hygiene Con- ference and the American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) meeting. In ad- dition he wrote chapters in Air Pollution by Stern, Industrial Hygiene and Toxicology by Patty, Uranium Production Tech- nology by Harrington and Rueble, and was the Associate Editor of Industrial Hygiene Aspects of Plant Operations: Volume 3 - Engineering Considerations in Equipment Selec-


tion, Layout and Building Design by Crawley and Crawley.

Besides his innovative ventilation design, Cap developed a method for testing laboratory fume hoods which won the Best Paper of the Year award of the Michigan Industrial Hygiene Society in 1982, which later became the basis for the ASHRAE Standard 110-1995, “Method of Testing Labora- tory Fume Hood Performance.” Cap was a significant partici- pant in the development of the ANSI Standard Z9.5-1992, “American National Standard for Laboratory Ventilation.” He was the first to employ “clean air islands” to supplement local exhaust ventilation where necessary.

Cap has been active in several societies: ACGIH (Commit- tee on Industrial Ventilation), Air Pollution Control Associa- tion (Committee on Dust, Fume, and Mist Control), American Industrial Hygiene Association (Board of Directors, Air Pol- lution Control Committee), ASHRAE ( Industrial Ventila- tion, Industrial Process Air Cleaning), American National Standards Committee (Air Pollution Committee, Health and Safety Committee), American Board of Industrial Hygiene.

Cap was born in St. Louis, Missouri. He earned his bache- lor’s and master’s degree in chemical engineering from Wash- ington University in the 1940s. He served in the Commissioned Corps of the U.S. Public Health Services. He worked as a chemical engineer and ventilation engineer at Ralston Purina Company and Mallinckrodt Chemical, Ura- nium Division. He also worked for the St. Louis County Health Department and the Michigan Department of Health as an industrial hygienist. In addition, Cap did consulting work, primarily as a ventilation engineer for Industrial Health Engineering Associates (co-founder), Pace Incorporated, and Rust Environment and Infrastructure.


Industrial Ventilation: A Manual of Recommended Practice is the outgrowth of years of experience by members of the ACGIH Industrial Ventilation Committee members and a com- pilation of research data and information on design, mainte- nance, and evaluation of industrial exhaust ventilation systems. The Manual attempts to present a logical method of designing and testing these systems. It has found wide acceptance as a guide for official agencies, as a standard for industrial ventilation designers, and as a textbook for industrial hygiene courses.

The Manual is not intended to be used as law, but rather as a guide. Because of new information on industrial ventilation becoming available through research projects, reports from en- gineers, and articles in various periodicals and journals, review and revision of each section of the Manual is an ongoing Com- mittee project. The Manual is available as a hardbound book and on CD-ROM. In a constant effort to present the latest techniques and data, the Committee desires, welcomes, and actively seeks comments and suggestions on the accuracy and adequacy of the information presented herein.

In this 23rd edition, the Committee has made a number of minor revisions. Chapter 5 includes updated duct calculation sheets designed to aid in calculations. The “3 eye” duct friction charts have been replaced with tables to permit easier determi- nation of the duct friction factor. The metric supplement has been

deleted and the Committee has developed a separate metric manual.

This publication is designed to present accurate and authoritative information with regard to the subject matter covered. It is distributed with the understanding that nei- ther the Committee nor its members collectively or indi- vidually assume any responsibility for any inadvertent misinformation, omissions, or for the results in the use of this publication.


R.T. Hughes, NIOSH, Ohio, Chair

A.G. Apol, FEOH, Washington

W.M. Cleary, Retired, Michigan

M.T. Davidson, The New York Blower Co., Indiana T.N. Do, NFESC, California

Mrs. Norma Donovan, Editorial Consultant

S.E. Guffey, U. of Washington, Washington

G.S. Knutson, Knutson Ventilation Consultants, Minnesota G. Lanham, KBD/Technic, Ohio

kK. Mead, NIOSH, Ohio

K.M. Paulson, NFESC, California

O.P. Petrey, Phoenix Process Equipment Co., Kentucky A.L. Twombly, Pfeiffer Engineering Co. Inc., Kentucky


Industrial Ventilation is a true Committee effort. It brings into focus in one source useful, practical ventilation data from all parts of the country. The Committee membership of indus- trial ventilation and industrial hygiene engineers represents a diversity of experience and interest that ensures a well- rounded, cooperative effort.

From the First Edition in 1951, this effort has been success- ful as witnessed by the acceptance of the "Ventilation Man- ual" throughout industry, by governmental agencies, and as a worldwide reference and text.

The present Committee is grateful for the faith and firm foundation provided by past Committees and members listed below. Special acknowledgment is made to the Division of

Occupational Health, Michigan Department of Health, for contributing their original field manual which was the basis of the First Edition, and to Mr. Knowlton J. Caplan who supervised the preparation of that manual.

The Committee is grateful also to those consultants who have contributed so greatly to the preparation of this and previous editions of /ndustrial Ventilation and to Mrs. Norma Donovan, Secretary to the Committee, for her untiring zeal in our efforts.

To many other individuals and agencies who have made specific contributions and have provided support, sugges- tions, and constructive criticism, our special thanks.


Previous Members

A.G. Apol, 1984—present

H. Ayer, 1962-1966

R.E. Bales, 1954-1960

J. Baliff, 1950-1956; Chair, 1954-1956

J.T. Barnhart, Consultant, 1986-1990

J.C. Barrett, 1956-1976; Chair, 1960-1968

J.L. Beltran, 1964-1966

D. Bonn, Consultant, 1958-1968

D.J. Burton, 1988-1970

K.J. Caplan, 1974-1978; Consultant, 1980-1986 W.M. Cleary. 1978-1993; Consultant, 1993-present; Chair, 1978-1984

L. Dickie, 1984-1994; Consultant 1968-1984 B. Feiner, 1956-1968

M. Franklin, 1991-1994

S.E. Guffey, 1984-present

G.M. Hama, 1950-1984; Chair, 1956-1960

R.P, Hibbard, 1968-1994

R.T. Hughes, 1976-present; Chair, 1989-present H.S. Jordan, 1960-1962

J. Kane, Consultant, 1950-1952


J. Kayse, Consultant, 1956-1958

J.F. Keppler, 1950-1954, 1958-1960

G.W. Knutson, Consultant, 1986-present J.J. Loeffler, 1980-1995; Chair, 1984-1989 J. Lumsden, 1962-1968

J.R. Lynch, 1966-1976

G. Michaelson, 1958-1960

K.M. Morse, 1950-1951; Chair, 1950-1951 R.T. Page, 1954-1956

K.M. Paulson, 1991-present

O.P. Petrey, Consultant, 1978-present

G.S. Rajhans, 1978-1995

K.E. Robinson, 1950-1954; Chair, 1952-1954 A. Salazar, 1952-1954

E.L. Schall, 1956-1958

M.M. Schuman, 1962-1994; Chair, 1968-1978 J.C. Soet, 1950-1960

A.L. Twombly, Consultant, 1986-present J. Willis, Consultant, 1952-1956

R. Wolle, 1966-1974

J.A. Wunderle, 1960-1964


Aerosol: An assemblage of small particles, solid or liquid, suspended in air. The diameter of the particles may vary from 100 microns down to 0.01 micron or less, e.g., dust, fog, smoke.

Air Cleaner: A device designed for the purpose of remov- ing atmospheric airborne impurities such as dusts, gases, vapors, fumes, and smoke. (Air cleaners include air washers, air filters, eletrostatic precipitators, and charcoal filters.)

Air Filter: An air cleaning device to remove light particu- late loadings from normal atmospheric air before intro- duction into the building. Usual range: loadings up to 3 grains per thousand cubic feet (0.003 grains per cubic foot). Note: Atmospheric air in heavy industrial areas and in-plant air in many industries have higher loadings than this, and dust collectors are then indicated for proper air cleaning.

Air Horsepower: The theoretical horsepower required to drive a fan if there were no loses in the fan, that is, if its efficiency were 100 percent.

Air, Standard: Dry air at 70 F and 29.92 in (Hg) barometer. This is substantially equivalent to 0.075 Ib/ft3. Specific heat of dry air = 0.24 btu/Ib/F.

Aspect Ratio: The ratio of the width to the length; AR = WIL.

Aspect Ratio of an Elbow: The width (W) along the axis of the bend divided by depth (D) in plane of bend; AR =W/D.

Blast Gate: Sliding damper.

Blow (throw): In air distribution, the distance an air stream travels from an outlet to a position at which air motion along the axis reduces to a velocity of 50 fpm. For unit heaters, the distance an air stream travels from a heater without a perceptible rise due to temperature difference and loss of velocity.

Brake Horsepower. The horsepower actually required to drive a fan. This includes the energy losses in the fan and can be determined only by actual test of the fan. (This does not include the drive losses between motor and fan.)

Capture Velocity: The air velocity at any point in front of the hood or at the hood opening necessary to overcome opposing air currents and to capture the contaminated air at that point by causing it to flow into the hood.


Coefficient of Entry: The actual rate of flow caused by a given hood static pressure compared to the theoretical flow which would result if the static pressure could be converted to velocity pressure with 100 percent effi- ciency. It is the ratio of actual to theoretical flow.

Comfort Zone (Average): The range of effective tempera- tures over which the majority (50% or more) of adults feel comfortable.

Convection: The motion resulting in a fluid from the differences in density and the action of gravity. In heat transmission, this meaning has been extended to in- clude both forced and natural motion or circulation.

Density: The ratio of the mass of a specimen of a substance to the volume of the specimen. The mass of a unit volume of a substance. When weight can be used with- out confusion, as synonymous with mass, density is the weight of a unit volume of a substance.

Density Factor: The ratio of actual air density to density of standard air. The product of the density factor and the density of standard air (0.075 lb/ft3) will give the actual air density in pounds per cubic foot; d x 0.075 = actual density of air, Ibs/ft3.

Dust: Small solid particles created by the breaking up of larger particles by processes crushing, grinding, drill- ing, explosions, etc. Dust particles already in existence in amixture of materials may escape into the air through such operations as shoveling, conveying, screening, sweeping, etc.

Dust Collector: An air cleaning device to remove heavy particulate loadings from exhaust systems before dis- charge to outdoors. Usual range: loadings 0.003 grains per cubic foot and higher.

Entry Loss: Loss in pressure caused by air flowing into a duct or hood (inches H,O).

Fumes: Small, solid particles formed by the condensation of vapors of solid materials.

Gases: Formless fluids which tend to occupy an entire space uniformly at ordinary temperatures and pres- sures.

Gravity, Specific: The ratio of the mass of a unit volume of a substance to the mass of the same volume of a standard substance at a standard temperature. Water at 39.2 F is the standard substance usually referred to. For gases, dry air, at the same temperature and pressure as the gas, is often taken as the standard substance.

xiv Industrial Ventilation

Hood: A shaped inlet designed to capture contaminated air and conduct it into the exhaust duct system.

Humidity, Absolute. The weight of water vapor per unit volume, pounds per cubic foot or grams per cubic centimeter.

Humidity, Relative: The ratio of the actual partial pressure of the water vapor in a space to the saturation pressure of pure water at the same temperature.

Inch of Water: A unit of pressure equal to the pressure exerted by a column of liquid water one inch high at a standard temperature.

Lower Explosive Limit: The lower limit of flammability or explosibility of a gas or vapor at ordinary ambient temperatures expressed in percent of the gas or vapor in air by volume. This limit is assumed constant for tem- peratures up to 250 F. Above these temperatures, it should be decreased by a factor of 0.7 since explosibility increases with higher temperatures.

Manometer: An instrument for measuring pressure; essen- tially a U-tube partially filled with a liquid, usually water, mercury or a light oil, so constructed that the amount of displacement of the liquid indicates the pres- sure being exerted on the instrument.

Micron: A unit of length, the thousandth part of 1 mm or the millionth of a meter (approximately 1/25,000 of an inch).

Minimum Design Duct Velocity: Minimum air velocity required to move the particulates in the air stream, fpm.

Mists: Small droplets of materials that are ordinarily liquid at normal temperature and pressure.

Plenum: Pressure equalizing chamber.

Pressure, Static: The potential pressure exerted in all di- rections by a fluid at rest. For a fluid in motion, it is measured in a direction normal to the direction of flow. Usually expressed in inches water gauge when dealing with air. (The tendency to either burst or collapse the

pipe.) Pressure, Total: The algebraic sum of the velocity pressure and the static pressure (with due regard to sign).

Pressure, Vapor: The pressure exerted by a vapor. If a vapor is kept in confinement over its liquid so that the vapor can accumulate above the liquid, the temperature being held constant, the vapor pressure approaches a fixed limit called the maximum or saturated vapor pres-

sure, dependent only on the temperature and the liquid. The term vapor pressure is sometimes used as synony- mous with saturated vapor pressure.

Pressure, Velocity: The kinetic pressure in the direction of flow necessary to cause a fluid at rest to flow at a given velocity. Usually expressed in inches water gauge.

Radiation, Thermal (Heat) Radiation: The transmission of energy by means of electromagnetic waves of very long wave length. Radiant energy of any wave length may, when absorbed, become thermal energy and result in an increase in the temperature of the absorbing body.

Replacement Air: A ventilation term used to indicate the volume of controlled outdoor air supplied to a building to replace air being exhausted.

Slot Velocity: Linear flow rate of contaminated air through slot, fpm.

Smoke: Anair suspension (aerosol) of particles, usually but not necessarily solid, often originating in a solid nu- cleus, formed from combustion or sublimation.

Temperature, Effective: An arbitrary index which com- bines into a single value the effect of temperature, humidity, and air movement on the sensation of warmth or cold felt by the human body. The numerical value is that of the temperature of still, saturated air which would induce an identical sensation.

Temperature, Wet-Bulb: Thermodynamic wet-bulb tem- perature is the temperature at which liquid or solid water, by evaporating into air, can bring the air to saturation adiabatically at the same temperature. Wet- bulb temperature (without qualification) is the tempera- ture indicated by a wet-bulb psychrometer constructed and used according to specifications.

Threshold Limit Values (TLVs): The values for airborne toxic materials which are to be used as guides in the control of health hazards and represent time-weighted concentrations to which nearly all workers may be exposed 8 hours per day over extended periods of time without adverse effects (see Appendix).

Transport (Conveying) Velocity: See Minimum Design Duct Velocity.

Vapor: The gaseous form of substances which are nor- mally in the solid or liquid state and which can be changed to these states either by increasing the pressure or decreasing the temperature.


Ef 2 A dui ABE Au oe inh fee tee Pe OO Ret de Se SS area BCH seed eee ee oe flow rate at actual condition APS * Sig eed a3 le adhere 8 ae os air horsepower ARS ct be ss Beanies Bk aspect ratio Pooky gee inane! bh ak ae eg ee oas A phe ead Slot area Bick asa PS BS oo ook ee oe barometric pressure GHP: Mecoree Beta hoe: ee ASS brake horsepower DADs sede 8 Seah hae brake horsepower, actual bhpe. ve ee WOE A brake horsepower, standard air Dt.” te te degregeenr delay na hree ie Gree British thermal unit btthcc sc. eo eee OS SE ees btu/hr Cer ok een Dd i Soba Bae Gos coefficient of entry CIM. -jatechs Wis a eee o cubic feet per minute CLR eo Sand LBA hey centerline radius Doe id Se Reet Apa th A ae aes diameter is Sh Ahk Ge he ees oe ade ae get density factor EET. sceesin taba oy ong Amar as aes es effective temperature PAs seh talk RA eas degree, Fahrenheit Bijele foe eae eS duct entry loss coefficient Pajcaperdteves d.6: Mt apie ee eta te elbow loss coefficient Fa eect bo ate te ke Hewes Go dah entry loss coefficient PDI <b 5 RE tee hs ee Pea feos Ge 2 feet per minute EPSPs gee hin @ te Ae EAS Ee ars feet per second Fey tahoe he Ee es slot loss coefficient TET partectuearbete Miwa tes seh ath soc hee choad square foot fk. ea AS EE SS laa e eh ws cubic foot Be yh cae Bah ou & hie Re gravitational force, ft/sec/sec SPM G dol any Pei at eh ee gallons per minute OT 5 dense Se! of Se ON Toes Wale, een hace Sy ess ele oe grains lige Bie! eb R LES RASS ee duct entry loss Wiis ema cote Le elt cao Ml ei overall hood entry loss Wad tise ee SAG BAe ate eae ES elbow loss Pigg ca eh ral og ie Bee Sey A A oh pe a ie a entry loss HEPA ....... high-efficiency particulate air filters Apidae hate tl Be esta BS loss in straight duct run He eee ty 2S Bk ee duct loss coefficient Ap? sScee yas Bk eet ou ee elk Nb A horsepower HE ee ok eS ei aie Be She io auieal @ oa hour Ne ee etd elt Ge aha td slot or opening entry loss VAS Aegis 2. coed te Wine Ad RE a Se at AB A ES eee inch


1 8.8, Ske Br oe od ADS ages om square inch TWEE rs che opted nes i. A me es ae Beats inches water gauge IBes 9 glare due debe meted Oh Genes & pound WOT 2 o8h ge. cach ech a dak eee ee AA SE ah ag! pound mass LEL* s&s afeu 8s piece hele se lower explosive limit MEF $ fog aren ek Ge BARRY mechanical efficiency MG as Fed a tubal Bada s et eee anges milligram MING Agsioe tee ie ate, Aang Bl ses minute TANS 0%, 4 4 atate a Sia iP Sa, poh es millimeter MRT a can Rod ee ee mean radiant temperature MW. org: ds Ae a ae ahs ok molecular weight Dh ale Saeed coi ae Ae 42 4 density of air in Ib/ft? DPM) 3.6) win Poh SAE SB hae parts per million PSE: 205.4 a aco dye lo BL ae WAP ee pounds per square inch PWReiid te Go Se ee Ae ead le id power ite FecaQreck be Sms Sic ds OE Be aoe flow rate in cfm Onn fog ata e ey corrected flow rate at a junction Re 2 ys Sera toe atte te A ¥ pie S Sod degree, Rankin RES 2 5 eek at ek ale fate oe relative humidity PPM 2. 5h Rak ds ok Ee revolutions per minute SCHM: sf ewido a 0k flow rate at standard condition SEPM ace setae hee a surface feet per minute SP Blt ioe any he tas don pare co specific gravity SP ses! ee sertene Gabe ea es & Searcy static pressure OP pie Sok higher static pressure at junction of 2 ducts SPke: tite ee al Gl ee GO ew BA hood static pressure Det wate le Se ROA Sp, system handling standard air SDP 8.5 teeta standard temperature and pressure GN? o> ite dei k ee ar etn the Threshold Limit Value TP aires ict A a Be oe BRR Gh on A total pressure Mi 2 Sidh Tints A ee ne Ak th Wate, Boag velocity, fpm Vay Bead i tech ey oe Se Spee, dikateoe De duct velocity VPS 2 Soke dc deen Byte aye Selec eed velocity pressure WP av eriraye dk fd) ee ate duct velocity pressure MP oe sg Reels See ee ee resultant velocity power MiP Bch ts Fas ti bya Ble aly Wit slot velocity pressure Vid daskvg pik chet, de dod oe Re es Slot velocity Vi as Ue ATAU wg Ae Wisede eS duct transport velocity We so ska feos Bie Gap TE ay SP ead Gi cin de eae ce aha watt


12) SUPPLY SYSTEMS*..2 i ohare eee ee eat 4 1-2 1.7.1 FrictionLosses......0.-2....-20-. 1-7 1.3 EXHAUSTSYSTEMS ................. 1-2 1.7.2 FittingLosses ................. 1-9 14 BASIC DEFINITIONS ................. 1-3 1.8 MULTIPLE-HOOD EXHAUST SYSTEMS ..... 1-9 1.5 PRINCIPLES OF AIRFLOW. ............. 1-4 19 AIRFLOW CHARACTERISTICS OF BLOWING 1.6 ACCELERATION OF AIR AND HOOD ENTRY AND EXHAUSTING ... 0.2... 06500006. 1-10 LOSSES 6. 6s ee ie bee Sse ae ade oe 8 1-6 REFERENCES icine se ede dee at gage @ aoe ak Ac alt Bs 1-10 Figure 1-1 SP, VP, and TPataPoint............. 1-4 Figure 1-5 Variation of SP, VP, and TP Through a Ventilation Figure 1-2 Measurement of SP, VP, and TP in a Pressurized SYStEM & 6-8 oN Aldi ea Ge ee aS Se ER Tan Ge 1-6 DUG Ey 8 5098 5s oy toe, eck so, ee agit 1-4 Figure 1-6 Moody Diagram... 2... ..0.-.0.0004. 1-8 Figure 1-3 SP, VP, and TP at Points in a Ventilation System 1-5 Figure 1-7 Blowing Vs. Exhausting ............ 1-10

Figure 1-4

Volumetric Flow Rates in Various Situations .. 1-5

1-2 Industrial Ventilation


The importance of clean uncontaminated air in the indus- trial work environment is well known. Modern industry with its complexity of operations and processes uses an increasing number of chemical compounds and substances, many of which are highly toxic. The use of such materials may result in particulates, gases, vapors, and/or mists in the workroom air in concentrations that exceed safe levels. Heat stress can also result in unsafe or uncomfortable work environments. Effective, well-designed ventilation offers a solution to these problems where worker protection is needed. Ventilation can also serve to control odor, moisture, and other undesirable environmental conditions.

The health hazard potential of an airborne substance is characterized by the Threshold Limit Value (TLV®). The TLV refers to the airborne concentration of a substance and repre- sents conditions under which it is believed that nearly all workers may be exposed day after day without adverse health effects. The time-weighted average (TWA) is defined as the time-weighted average concentration for a conventional 8- hour workday and a 40-hour workweek which will produce no adverse health effects for nearly all workers. The TLV-—TWA is usually used to determine a safe exposure level. TLVs are published annually by the American Conference of Governmental Industrial Hygienists (ACGIH); revisions and additions are made regularly as information becomes avail- able. Appendix A of this Manual provides the current TLV list for chemical substances as of the date of publication.

Ventilation systems used in industrial plants are of two generic types. The SUPPLY system is used to supply air, usually tempered, to a work space. The EXHAUST system is used to remove the contaminants generated by an operation in order to maintain a healthful work environment.

A complete ventilation program must consider both the supply and the exhaust systems. If the overall quantity of air exhausted from a work space is greater than the quantity of outdoor air supplied to the space, the plant interior will experience a lower pressure than the local atmospheric pres- sure. This may be desirable when using a dilution ventilation system to control or isolate contaminants in a specific area of the overall plant. Often, this condition occurs simply because local exhaust systems are installed and consideration is not given to the corresponding replacement air systems. Air will then enter the plant in an uncontrolled manner through cracks, walls, windows, and doorways. This typically results in: 1) employee discomfort in winter months for those working near the plant perimeter, 2) exhaust system performance degrada- tion, possibly leading to loss of contaminant control and a potential health hazard, and 3) higher heating and cooling costs. Chapter 7 of this Manual discusses these points in more detail.


Supply systems are used for two purposes: 1) to create a

comfortable environment in the plant (the HVAC system); and 2) to replace air exhausted from the plant (the REPLACE- MENT system). Many times, supply and exhaust systems are coupled, as in dilution control systems (see Section 1.3 and Chapter 2.)

A well-designed supply system will consist of an air inlet section, filters, heating and/or cooling equipment, a fan, ducts, and register/grilles for distributing the air within the work space. The filters, heating and/or cooling equipment and fan are often combined into a complete unit called an airhouse or air supply unit. If part of the air supplied by a system is recirculated, a RETURN system is used to bring the air back to the airhouse.


Exhaust ventilation systems are classified in two generic groups: 1) the GENERAL exhaust system and 2) the LOCAL exhaust system.

The general exhaust system can be used for heat control and/or removal of contaminants generated in a space by flushing out a given space with large quantities of air. When used for heat control, the air may be tempered and recycled. When used for contaminant control (the dilution system), enough outdoor air must be mixed with the contaminant so that the average concentration is reduced to a safe level. The contaminated air is then typically discharged to the atmos- phere. A supply system is usually used in conjunction with a general exhaust system to replace the air exhausted.

Dilution ventilation systems are normally used for con- taminant control only when local exhaust is impractical, as the large quantities of tempered replacement air required to offset the air exhausted can lead to high operating costs. Chapter 2 describes the basic features of general ventilation systems and their application to contaminant and fire hazard control.

Local exhaust ventilation systems operate on the principle of capturing a contaminant at or near its source. It is the preferred method of control because it is more effective and the smaller exhaust flow rate results in lower heating costs compared to high flow rate general exhaust requirements. The present emphasis on air pollution control stresses the need for efficient air cleaning devices on industrial ventilation sys- tems, and the smaller flow rates of the local exhaust system result in lower costs for air cleaning devices.

Local exhaust systems are comprised of up to four basic elements: the hood(s), the duct system (including the exhaust stack and/or recirculation duct), the air cleaning device, and the fan. The purpose of the hood is to collect the contaminant generated in an air stream directed toward the hood. A duct system must then transport the contaminated air to the air cleaning device, if present, or to the fan. In the air cleaner, the contaminant is removed from the air stream. The fan must overcome all the losses due to friction, hood entry, and fittings

in the system while producing the intended flow rate. The duct on the fan outlet usually discharges the air to the atmosphere in such a way that it will not be re-entrained by the replace- ment and/or HVAC systems. In some situations, the cleaned air is returned to the plant. Chapter 7 discusses whether this is possible and how it may be accomplished.

This Manual deals with the design aspects of exhaust ventilation systems, but the principles described also apply to supply systems.


The following basic definitions are used to describe air flow and will be used extensively in the remainder of the Manual.

The density (p) of the air is defined as its mass per unit volume and is normally expressed in pounds mass per cubic foot (bm/ft*). At standard atmospheric pressure (14.7 psia), room temperature (70 F) and zero water content, its value is normally taken to be 0.075 Ibm/ft?, as calculated from the perfect gas equation of state relating pressure, density, and temperature:

p=pRT [1.1]

where: p= the absolute pressure in pounds per square foot absolute (psfa) p = the density,