ANSI—American National Standards Institute

API—American Petroleum Institute

ASTM—American Society for Testing and Materials

BHP—Brake horsepower

BSCO—Brake specific carbon monoxide

BSHC—Brake specific hydrocarbons

BSNOX—Brake specific oxides of nitrogen

°C—Celsius

cfh—cubic feet per hour

cfm—cubic feet per minute

CFV—Critical flow venturi

CL—Chemiluminescence

CO—Carbon monoxide

CO2—Carbon dioxide

cu in—cubic inch(es)

CVS—Constant volume sampler

EP—End point

EPA—Environmental Protection Agency

°F—Fahrenheit

FEL—Family emission limit

FID—Flame ionization detector

ft—foot or feet

g—gram(s)

gal—U.S. gallon

GC—Gas Chromatograph

h—hour(s)

H2O—water

HC—hydrocarbon

HFID—Heated flame ionization detector

Hg—Mercury

hp—horsepower

IBP—Initial boiling point

in—inch(es)

K—Kelvin

kg—kilogram(s)

km—kilometer(s)

kPa—kilopascal(s)

lb—pound(s)

LPG—Liquified Petroleum Gas

m—meter(s)

max—maximum

mg—milligram(s)

mi—mile(s)

min—minute

ml—milliliter(s)

mm—millimeter

mph—miles per hour

mv—millivolt(s)

N2—nitrogen

NDIR—Nondispersive infrared

NMHC—Non-methane hydrocarbons

NO—nitric oxide

NO2—nitrogen dioxide

NOX—oxides of nitrogen

No.—number

O2—oxygen

pct—percent

PM—particulate matter

ppm—parts per million by volume

ppmC—parts per million, carbon

psi—pounds per square inch

psig—pounds per square inch gauge

°R—Rankin

rpm—revolutions per minute

s—second(s)

SAE—Society of Automotive Engineers

SI—International system of units (i.e., metric)

THCE—Total hydrocarbon equivalent

U.S.—United States

V—volt(s)

vs—versus

W—watt(s)

wt—weight