Table Of ContentENGINEERING
REFERENCE MANUAL
Third Edition
Edited by
Michael D. Larrañaga, PhD, CIH, CSP, PE
Copyright AIHA® For personal use only. Do not distribute.
Engineering Reference Manual, 3rd Edition
Introduction
Readers who are familiar with previous editions of the manual will recognize a number
of significant changes to the publication. Every chapter has been updated with the goal
of providing current information, expanding where appropriate, and adding new topics
and subjects that have only recently become recognized as a part of the knowledge
base of the industrial hygiene community. In addition to the changes in content, the
manual has been enlarged in size; it won’t fit in your pocket as well, but it will fit your
bookshelf better in this edition.
Among the notable changes to the manual are:
• • Expansion of the conversions tables and a move to embrace the SI System as
the units of choice for the industrial hygiene profession and community.
• • Expanded treatment of the subject of airborne concentration generation and
measurement.
• • Inclusion of subjects new to the manual, such as Illumination.
• • Addition of subjects not traditional in the practice of industrial hygiene, such
as Life Safety Engineering, Fire Safety, and Illumination.
Given the extent of changes, the AIHA® Engineering Reference Manual will require
time for growing pains as the inevitable errors and omissions are discovered and cor-
rected. The AIHA solicits input from readers and users regarding the contents, style,
and presentation of the manual; comments should be addressed to AIHA® at 3141 Fair-
view Park Drive, Suite 777, Falls Church, VA 22042; or via email: [email protected].
AIHA® hopes that readers and users will be pleased with the changes and additions to
the Engineering Reference Manual. It is the hope and wish of the Engineering Com-
mittee that the manual will continue to be a valuable aid to members of the industrial
hygiene community as well as to the broader community of health and safety profes-
sionals.
Copyright AIHA® vii For personal use only. Do not distribute.
Table of Contents
Foreword .........................................................................................................................v
Introduction ..................................................................................................................vii
Chapter 1: Metrology for Industrial Hygiene .............................................................1
Michael D. Larrañaga
Chapter 2: IH Concentration Conversion, Generation, ..........................................19
and Measurement
Angel Plaza and Michael D. Larrañaga
Chapter 3: Ventilation .................................................................................................35
D. Jeff Burton
Chapter 4: Noise ...........................................................................................................59
Angel Plaza
Chapter 5: Human Thermal Stress and Strain .........................................................75
Jiun-Yin Jian and Michael D. Larrañaga
Chapter 6: Ionizing Radiation ....................................................................................99
Ed Maher
Chapter 7: Nonionizing Radiation ...........................................................................115
Ed Maher
Chapter 8: Respiratory Protection ...........................................................................155
Fred N. Bolton
Chapter 9: Ergonomics ..............................................................................................175
Jiun-Yin Jian and Magdy Akladios
Chapter 10: Illumination ...........................................................................................195
Q.S. Wang and Michael D. Larrañaga
Chapter 11: Life Safety Engineering ........................................................................207
Pat Brock and Christopher Foeller
Chapter 12: Process Hazard Analysis ......................................................................219
Q.S. Wang and J.D. Brown
Chapter 13: Indoor Environmental Quality ............................................................239
Eric Althouse and H.W. Holder
Chapter 14: Fire Safety .............................................................................................253
Gary Q. Johnson
Copyright AIHA® For personal use only. Do not distribute.
Engineering Reference Manual, 3rd Edition
Chapter 1:
Metrology for Industrial Hygiene
By Michael D. Larrañaga, PhD, CIH, CSP, PE
This compilation establishes a preferred set of units for AIHA® publications and pro-
vides the practicing industrial hygienist with a comprehensive set of conversion tools
from traditional industrial hygiene units to the preferred units. When special units are
required, they should be defined in terms of the seven dimensionally independent base
units of the Standard International (SI) System. For the first time, major features of the
US Standard Atmosphere are included to allow quick reference for conversions from
standard conditions at sea level, 45EN latitude, 1 atm, and 59 EF to and from station
standard conditions used in weather reports.
Table 1.1 – SI Base Units, Names, and Symbols(1)
Physical Quantity Name Symbol
length meter m
mass kilogram kg
time second s
electric current ampere A
thermodynamic temperature kelvin K
amount of substance mole mol
luminous intensity candela cd
Table 1.2 – SI Prefixes(1)
Factor Prefix Symbol Factor Prefix Symbol
1 none none 1 none none
10-1 deci d 101 deka da
10-2 centi c 102 hecto h
10-3 milli m 103 kilo k
10-6 micro μ 106 mega M
10-9 nano n 109 giga G
10-12 pico p 1012 tera T
10-15 femto f 1015 peta P
10-18 atto a 1018 exa E
10-21 zepto z 1021 zetta Z
10-24 yocto y 1024 yotta Y
Prefix symbols should be printed in Roman (upright) type with no space between the
prefix and the unit symbol.
Copyright AIHA® 1 For personal use only. Do not distribute.
CHAPTER 1: Metrology for Industrial Hygiene
A combined prefix and symbol becomes a new symbol that can be raised to any power
without use of parentheses. Examples: 1 cm3 = (0.01 m)3 = 10-6 m3; 1 μs-1 = (10-6 s)-1 =
106/s.
The multiples and submultiples for mass are constructed by using the appropriate
prefix to the word gram and symbol g. Examples: mg, not μkg; Mg, not kkg. Never use
multiple prefixes with any symbol.
Table 1.3 – SI Derived Units and Other Units with Special Names(1-4)
SI Unit Expression in terms of
Physical Quantity
Symbol Name SI Base Units Other Units
Frequency Hz hertz s-1 cycles/s
Force N newton m kg s-2
Pressure, stress Pa pascal m-1 kg s-2 N/m2
energy, work, heat J joule m2 kg s-2 N m, m3 Pa, VC
power, radiant flux W watt m2 kg s-3 J/s, V A, Pa m3/s, N m/s
electric charge C coulomb s A
electric potential V volt m2 kg s-3 A-1 J/C, W/A
electric resistance Ω ohm m2 kg s-3 A-2 V/A
electric conductance S siemens m-2 kg-1 s3 A2 Ω-1 = A/V
electric capacitance F farad m-2 kg-1 s4 A2 C/V
Magnetic flux density T tesla kg s-2 A-1 Wb/m2
Magnetic flux Wb weber m2 kg s-2 A-1 V s
Magnetic inductance H henry m2 kg s-2 A-2 Wb/A
Temperature interval EC degree Celsius K
Luminous flux lm lumen cd sr
Illuminance lx lux m-2 cd sr lm/m2
Radioactivity Bq becquerel s-1
Absorbed radiation dose Gy gray m2 s-2 J/kg
dose equivalent, injury Sv sievert m2 s-2 J/kg
Time min minute 60 s
Time h hour 3600 s
Time d day 86,400 s
plane angle E degree (π/180) rad
plane angle ' minute (π/10 800) rad
plane angle " second (π/648 000) rad
Length ∆ angstrom 10-10 m
Area b barn 10-28 m2
Volume L liter 10-3 m3 dm3
Mass t tonne 103 kg Mg
Pressure bar bar 105 N m-2 105 Pa
Copyright AIHA® 2 For personal use only. Do not distribute.
Engineering Reference Manual, 3rd Edition
Table 1.3 – SI Derived Units and Other Units with Special Names(1-4) (cont.)
SI Unit Expression in terms of
Physical Quantity
Symbol Name SI Base Units Other Units
Energy eV electronvolt .1.602 x 10-19 J
Mass u atomic mass 1.661 x 10-27 kg
unit
Mass Da daltona 1.661 x 10-27 kg
plane angle (arc/radius) radb radian m m-1 [1]
solid angle (area/radius2) srb steradian m2 m-2 [1]
level, field quantity B b, c bel9 (F/Fo)2 = 1Ψ [1B] LF = 2 lg(F/Fo) [B]
level, power quantity (P/Po) = 1Ψ [1B] LP = lg(P/Po) [B]
level, field quantity Np b, c neper2 (F/Fo) = eΨ [1Np] LF = ln(F/Fo) [Np]
level, power quantity (P/P) = e2Ψ [1Np] LP = (2) ln(P/Po) [Np]
o
Dynamic viscosity Pa s m-1 kg s-1 N s m /kg
Kinematic viscosity N s m /kg m2 s-1 Pa s m3/kg
moment of force N m m2 kg s-2
surface tension N/m kg s-2
heat flux density W/m2 kg s-3
Irradiance W/m2 kg s-3
heat capacity J/K m2 kg s-2 K-1
Entropy J/K m2 kg s-2 K-1
specific heat capacity J/(kg K) m2 s-2 K-1
specific entropy J/(kg K) m2 s-2 K-1
specific energy J/kg m2 s-2
thermal conductivity W/(m K) m kg s-3 K-1
energy density J/m3 m-1 kg s-2
electric field strength V/m m kg s-3 A-1
electric charge density C/m3 m-3 s A
electric flux density C/m2 m-2 s A
Permittivity F/m m-3 kg-1 s4 A2
Permeability H/m m kg s-2 A-2
molar energy J/mol m2 kg s-2 mol-1
molar heat capacity J/(mol K) m2 kg s-2 K-1 mol-1
molar entropy J/(mol K) m2 kg s-2 K-1 mol-1
Exposure (x and γ rays) C/kg kg-1 s A
Absorbed dose rate Gy/s m2 s-3
a 1 Dalton equals 1/12 the mass of a carbon 12 atom: Da=(m(12C)/12)
b These dimensionless ratios are supplemental to the SI system and may be used with other SI units or omitted as necessary for
clarity of presentation. More generally, the ratio of two quantities with the same units has an official SI unit of [1] = [unit]/[unit].
c Both bel and neper have two definitions: in terms of power quantities and field quantities. Power ratios are ratios of quantities
expressed in [W] or [J]. Field ratios can be expressed in [A] or [V] in electrical circuits, [A/m] or [V/m] in electromagnetic
fields, [m/s] or [N] in mechanical systems, and [m3/s] or [Pa] in fluid or acoustic systems. In all cases, the square of a field
quantity is proportional to the power quantity.
Copyright AIHA® 3 For personal use only. Do not distribute.
CHAPTER 1: Metrology for Industrial Hygiene
Table 1.4 – Natural Constants(3,5,6)
Quantity Symbol Value Units
speed of light in vacuum c 299 792 458 m s-1
vacuum permeability μ 4π x 10-7 = N A-2
o
12.57 x 10-7 N A-2
vacuum permittivity (1/μoc2) ε 8.854 x 10-12 F m-1, C2 J-1 m-1
o
Gravitational constant G 6.673 x 10-11 m3 kg-1 s-2
Planck constant h 6.626 x 10-34 J s
Elementary charge e 1.602 x 10-19 C, s A
electron mass m 0.5110 kg
e
5.486 x 10-4 u
energy equivalent mc2 9.109 x 10-31 MeV
e
proton mass m 1.673 x 10-27 kg
p
1.007 u
energy equivalent mc2 938.3 MeV
e
neutron mass m 1.675 x 10-27 kg
n
1.009 u
energy equivalent mc2 939.6 MeV
e
Avogadro constant N 6.022 x 1023 mol-1
A
Faraday constant, (N e) F 9.648 x 104 C/mol
A
molar gas constant, (N k) R 8.314 J mol-1 K-1
A
8.314 x 10-2 L bar K-1 mol-1
8.206 x 10-2 L atm K-1 mol-1
8.314 x 103 L Pa K-1 mol-1
Boltzmann constant, (R/N ) k 1.381 x 10-23 J K-1
A
Stefan-Boltzmann constant, ((π/60)k4/h3c2) σ 5.671 x 10-8 W m-2 K-4
atomic mass constant m 1.661 x 10-27 kg
u
electron volt eV 1.602 x 10-19 J
standard atmosphere atm 101 325 Pa
standard acceleration of gravity g 9.807 m s-2
standard molecular mass of dry air M 28.96 g/mol
a
circumference/diameter of circle π 3.141 59 [1]
base of natural logarithms e 2.718 28 [1]
half-life/time-constantd T /τ ln(2)=0.6931 [s/s] or [1]
1/2
d This conversion ensures equality of 2-t / T 1/2=e-t / τ.
Copyright AIHA® 4 For personal use only. Do not distribute.
Engineering Reference Manual, 3rd Edition
Table 1.5 – Acoustic References Quantities(4,7-9)
{The use of the term “log” in this table denotes log10 ; the more appropriate term is “lg”.}
Symbol Reference Description Level
p 20 μPa rms acoustic pressure3 in air or
o
gases with ρc = 400 [N s/m3]
sound pressure level L = 20 log(p/p) [dB]
p o
p 1 μPa rms acoustic pressure8 in other
o
gases, liquids, and solids
I 1 pW/m2 acoustic intensity8 sound intensity level L = 10 log(I/I) [dB]
o I o
W 1 pW acoustic power8 sound power level L = 10 log(W/W) [dB]
o W o
e 1 pJ sound energy8 sound energy level L = 10 log(e/e) [dB]
o e o
D 1 pJ/m3 sound energy density9 sound energy
o L = 10 log(D/D) [dB]
density level D o
E 400 μPa2 sound exposure8 sound exposure
o L = 10 log(E/E) [dB]
level E o
d 10 pm rms vibration displacemente structural
o L = 20 log(d/d) [dB]
displacement level d o
v 50 nm/s rms vibration velocity8 rms velocity level L = 20 log(v/v) [dB]
o v o
a 1 μm/s2 rms vibration acceleration8 rms acceleration
o L = 20 log(a/a) [dB]
level a o
F 1 μN rms vibration force8 rms force level L = 10 log(F/F) [dB]
o F o
f 1 Hz frequency4 frequency level L = 20 log(f/f) [dB]
o f o
c 346.2 m/s sea level speed of sound at NTP, dry air, 25 EC, 1 atm
o
<ρc> 400 rayls standard acoustic impedancef
o
c 340.3 m/s 45EN latitude, sea level, 15 EC , U.S. Standard Atmosphere Reference
std atm
Value
ρ 1.225 g/mol density at 1 atm, 15 EC, 0% R.H. , U.S. Standard Atmosphere Reference
std atm
Value
ρc 416.9 rayls acoustic impedance at 1 atm, 15 EC, 0% R.H.
std atm
cair 20.05 ∙[K] [m/s], speed of sound in air depends on absolute temperature
e ISO/TR 7849:1987(E). Appendix F says vo = 50 nm/s provides uniform reference for velocity levels, displacement levels,
and acceleration levels. Specifically, for narrow band measurements centered at frequency fm, Lv = La - 20 log(fm Hz/1 Hz)
+10 [dB].
f Note the importance of acoustic impedance: LI = Lp - 10 log(ρc/ρoco). LI measures the ability to damage hearing. LP is
reported by sound level meters. LI ̣ LP at sea level BTP. At other temperatures or pressures, correct LP to LI and compare LI
with hearing damage risk criteria.
Copyright AIHA® 5 For personal use only. Do not distribute.
CHAPTER 1: Metrology for Industrial Hygiene
Table 1.6 – The U.S. Standard Atmosphere Composition(6)
COMPOSITION OF DRY AIR, below 79 km above mean sea level
Gas M /[g/mol] Volume Fraction ρ /[g/L] { 0EC, 1 atm }
N 28.013 4 0.780 84 1.251
2
O 31.998 8 0.209 476 1.429
2
Ar 39.948 0.009 34 1.783
CO 44.009 95 0.000 314g 1.977
2
Ne 20.183 0.000 018 18 0.900
He 4.002 6 0.000 005 24 0.178 5
Kr 83.80 0.000 001 14 3.736
Xe 131.30 0.000 000 087 5.089
CH 16.043 03 0.000 002 0.716 8
4
H 2.015 94 0.000 000 5 0.089 9
2
air 0%RH 28.964 1.00 1.293
HO 18.015 3 variable in airh
2
g Carbon dioxide is closer to 354 ppm in 1990 data.
h Observed surface humidity extremes range from a dew point of 34 EC {93 EF} in Sharjah, Saudi Arabia, 1972, to a dew
point of -88 EC {-126 EF} in Vostok, Antarctica, 1970.5 Atmospheric mole fractions of water vapor range between 0.03 <
XH2O [μmolwater/molair] < 35 000.(3)
Table 1.7 – Sea Level Values of Atmospheric Properties, 45EN latitude(6)
Symbol Quantity Description
M 28.96 [g/mol] mean molecular mass
0
N 2.547 x 1025 [ m-3] number density
0
P 101 325 [N/m2] barometric pressure
0
T 288.15 [K] = 15 [EC] average annual temperature
0
V 23.64 [m3/kmol] molar volume
m, 0
H 0 [m] mean sea level altitude
0
L 6.633 x 10-8 [m] mean free path
0
V 4.589 x 102 [m/s] mean particle speed
0
η 1.461 x 10-5 [m2/s] mean kinematic viscosity
0
μ 1.789 x 10-5 [kg/m?s] mean dynamic viscosity
0
v 6.919 x 109 [s-1] mean collision frequency
0
ρ 1.225 [kg/m3] density
0
γ 1.4 [1] C/C = molar heat capacity ratio
P V
k 2.533 x 10-3 [J/sXmXK] thermal conductivity
t,0
Copyright AIHA® 6 For personal use only. Do not distribute.
Table 1.8 – Key Parameters of the U.S. Standard Atmosphere(3,6)
Altitude Gravitational Number Density Temperature Pressure Density Sound Speed Thermal Conductivity Acceleration
Z /[m] g /[m s-2] n /[1024 m-3] T /[K] P /[bar] ρ /[kg m-3] C /[m s-1] λa /[μJ/(m s K)]
-2000 9.8128 31.017 301.154 1.2778 1.4782 347.89 26.380
-1500 9.8113 29.346 297.902 1.2069 1.4114 346.00 26.129
-1000 9.8097 28.007 294.651 1.1393 1.3470 344.11 25.872
-500 9.8082 26.715 291.400 1.0747 1.2849 342.21 25.618
0 9.8066 25.470 288.150 1.0132 1.2250 340.29 25.326
500 9.8051 24.269 284.900 0.95461 1.1673 338.37 25.106
1000 9.8036 23.113 281.651 0.89876 1.1117 336.43 24.849
1500 9.8020 22.000 278.402 0.84559 1.0581 334.49 24.591
2000 9.8005 20.928 275.154 0.79501 1.0066 332.53 24.333
7
2500 9.7989 19.897 271.906 0.74691 0.95695 330.56 24.073
3000 9.7974 18.905 268.659 0.70121 0.90925 328.58 23.813
3500 9.7959 17.952 265.413 0.65780 0.86340 326.59 23.552
E
4000 9.7943 17.036 262.166 0.61660 0.81935 324.59 23.290 n
g
in
4500 9.7928 16.156 258.921 0.57752 0.77704 322.57 23.028 e
e
r
5000 9.7912 15.312 255.676 0.54048 0.73643 320.55 22.765 in
g
R
5500 9.7897 14.502 252.431 0.50539 0.69747 318.50 22.500 e
fe
6000 9.7882 13.725 249.187 0.47217 0.66011 316.45 22.236 ren
c
e
7000 9.7851 12.267 242.700 0.41105 0.59002 312.31 21.703 M
a
8000 9.7820 10.932 236.215 0.35651 0.52579 308.11 21.168 nu
a
9000 9.7789 9.7110 229.733 0.30800 0.46706 303.85 20.630 l, 3
rd
10000 9.7759 8.5976 223.252 0.26499 0.41351 299.53 20.088 E
d
itio
n
Copyright AIHA® For personal use only. Do not distribute.
