In an effort to eliminate the confusion created when trying to compare the specific power, which is an energy consumption metric, between two similar-sized compressors with slightly different rated discharge pressures, CAGI has introduced an efficiency rating value on its Compressor Data Sheets . . . Isentropic Efficiency. Isentropic efficiency incorporates operating pressure and greatly simplifies the process of comparing the efficiencies among several like-sized compressors each having slightly different full load operating pressures. For example, for the same horsepower compressors, one sheet may show 125 psig operating pressure and another may show 130 psig so comparing isentropic helps equalize the comparison.