Pressure * Volume = Pressure * Volume
ACFM = Actual Cubic Feet per Minute at the operating conditions
SCFM = Standard Cubic Feet per Minute at Standard Conditions
SCFM is normally used to designate flow in terms of some base or reference pressure, temperature and relative humidity. Many standards are used, the most common being the Compressed Air & Gas Institute (CAGI) and the American Society of Mechanical Engineers (ASME) standards, which are 14.7 PSIA, 68°F and 36% relative humidity (RH). This converts to a density of 0.075 lbs/cu.ft. for air.
CFM = cubic feet per minute
ICFM = inlet cubic feet per minute into the blower