Compressed-air calculator

Compressor flow test (load/unload)

A compressor’s actual in-service flow often differs from its datasheet: wear, fouling, intake conditions. The load/unload test measures it on site, without a flow meter, from a known volume and a stopwatch.

Enter the system volume, the pressures and the pump-up time: the calculator derives the delivered flow (isothermal compression assumption).

Flow test

Compressor flow from a load/unload test (isothermal compression in a receiver).

Receiver volume
Volume
Load pressure
Unload pressure
Time

Result

Compressor flowSCFM
Total volume
ft³
ΔP
psig
Time
s

Isothermal compression: SCFM = (V · ΔP_abs · 60) / (P_std · t). P_std = 14.5 psia (1 bar abs).

Indicative estimates — validate all results before any technical decision.