The abbreviations of this section apply to all subparts of this part and have the following meanings: ANSI--American National Standards InstituteAPI--American Petroleum InstituteASTM--American Society for Testing and MaterialsBHP--Brake horsepowerBSCO--Brake specific carbon monoxideBSHC--Brake specific hydrocarbonsBSNOX--Brake specific oxides of nitrogenC--Celsiuscfh--cubic feet per hourcfm--cubic feet per minuteCFV--Critical flow venturiCL--ChemiluminescenceCO--Carbon monoxideCO2--Carbon dioxidecu in--cubic inch(es)CVS--Constant volume samplerEP--End pointEPA--Environmental Protection AgencyF--FahrenheitFEL--Family emission limitFID--Flame ionization detectorft--foot or feetg--gram(s)gal--U.S. gallonGC--Gas Chromatographh--hour(s)H2O--waterHC--hydrocarbonHFID--Heated flame ionization detectorHg--Mercuryhp--horsepower IBP--Initial boiling pointin--inch(es)K--Kelvinkg--kilogram(s)km--kilometer(s)kPa--kilopascal(s)lb--pound(s)LPG--Liquified Petroleum Gasm--meter(s)max--maximummg--milligram(s)mi--mile(s)min--minuteml--milliliter(s)mm--millimetermph--miles per hourmv--millivolt(s)N2--nitrogenNDIR--Nondispersive infraredNMHC--Non-methane hydrocarbonsNO--nitric oxideNO2--nitrogen dioxideNOX--oxides of nitrogenNo.--numberO2--oxygenpct--percentPM--particulate matterppm--parts per million by volumeppmC--parts per million, carbonpsi--pounds per square inchpsig--pounds per square inch gaugeR--Rankinrpm--revolutions per minutes--second(s)SAE--Society of Automotive EngineersSI--International system of units (i.e., metric)THCE--Total hydrocarbon equivalentU.S.--United StatesV--volt(s)vs--versusW--watt(s)wt--weight