ASTM—American Society for Testing and Materials.

C—Celsius.

cc—Cubic centimetre(s).

cfh—Cubic feet per hour.

cfm—Cubic feet per minute.

CH4   methane.

cm—Centimetre(s).

CO—Carbon monoxide.

CO2—Carbon dioxide.

Conc—Concentration.

cu.—Cubic.

CVS—Constant volume sampler.

EGR—Exhaust gas recirculation.

EP—End point.

EPA—Environmental Protection Agency.

F—Fahrenheit.

h—hour.

HC—Hydrocarbon(s).

Hg—Mercury.

H2O—Water.

in.—Inch(es).

K—Kelvin.

kg—Kilogram(s).

km—Kilometre(s).

kpa—Kilopascals.

lb—Pound(s).

m—Metre(s).

mph—Miles per hour.

mm—Millimetre(s).

N2—Nitrogen.

N2O   nitrous oxide.

NOX—Oxides of nitrogen.

No.—Number.

O2—Oxygen.

Pa—Pascal(s).

Pb—lead.

ppm—Parts per million by volume.

psi—Pounds per square inch.

psig—Pounds per square inch gauge.

R—Rankine.

rpm—Revolutions per minute.

wt—Weight.

°—Degree(s).

%—Percent.