Used in this part are abbreviations and symbols of units of measure. These are defined as follows:

(a) System International (SI) units of measure:

A—ampere g—gram Hz—hertz J—joule K—degree Kelvin kg—kilogram m—meter m 3—cubic meter mg—milligram—10 −3 gram mm—millimeter—10 −3 meter Mg—megagram—10 6 gram mol—mole N—newton ng—nanogram—10 −9 gram nm—nanometer—10 −9 meter Pa—pascal s—second V—volt W—watt Ω—ohm µg—microgram—10 −6 gram

(b) Other units of measure:

Btu—British thermal unit °C—degree Celsius (centigrade) cal—calorie cfm—cubic feet per minute cu ft—cubic feet dcf—dry cubic feet dcm—dry cubic meter dscf—dry cubic feet at standard conditions dscm—dry cubic meter at standard conditions eq—equivalent °F—degree Fahrenheit ft—feet gal—gallon gr—grain g-eq—gram equivalent hr—hour in—inch k—1,000 l—liter lpm—liter per minute lb—pound meq—milliequivalent min—minute ml—milliliter mol. wt.—molecular weight ppb—parts per billion ppm—parts per million psia—pounds per square inch absolute psig—pounds per square inch gage °R—degree Rankine scf—cubic feet at standard conditions scfh—cubic feet per hour at standard conditions scm—cubic meter at standard conditions sec—second sq ft—square feet std—at standard conditions

(c) Chemical nomenclature:

CdS—cadmium sulfide CO—carbon monoxide CO2—carbon dioxide HCl—hydrochloric acid Hg—mercury H2O—water H2S—hydrogen sulfide H2SO4—sulfuric acid N2—nitrogen NO—nitric oxide NO2—nitrogen dioxide NOX—nitrogen oxides O2—oxygen SO2—sulfur dioxide SO3—sulfur trioxide SOX—sulfur oxides

(d) Miscellaneous:

A.S.T.M.—American Society for Testing and Materials [42 FR 37000, July 19, 1977; 42 FR 38178, July 27, 1977]