Pounds Per Square Inch (Gauge) (PSIG)

Unit of pressure that specifically denote the use of Gauge Pressure, or pressure using atmospheric pressure as a reference point. A pressure vessel at 0 PSIG actually contains fluid at atmospheric pressure, or about 14.7 PSIA. The “G” is frequently dropped when context is enough to indicate the basis point. For example, a compressed air pressure measurment of 10 PSI can be safely assumed to be PSIG, as 10 PSIA would actually be a coarse vacuum relative to ambient pressure.