Volumetric Capacity

Volumetric capacity defines how much air the machine can deliver per unit time. Cubic-feet per minute is the most common unit for this measure, although just what this is can vary between manufacturers. An attempt to standardize this measure, a so-called scfm, seems to be dependent on whose standards you follow. The Compressed Air and Gas Institute has adopted the ISO definition of an scfm as being dry air (0% relative humidity) at 14.5 psi and 68°F. Actual cfm, of acfm, is another measure of volumetric capacity. It relates the amount of compressed air delivered to the outlet of the compressor, which will always be less than the displacement of the machine owing to losses from blow-by through the compressor.