For Air compressors that have start/stop or load/unload controls, there is an easy way to estimate the amount of leakage in the system.
The Leak test method involves starting the compressor when there are no demands on the system. A number of measurements are taken to determine the average time it takes to load and unload the air compressor.
Leakage (%) = (T x 100) / (T + t )
where,
T = on-load time,
t = off-load time.
Leakage quantity will be expressed in terms of the percentage of compressor capacity lost.
The percentage lost to leakage should be less than 10% in a well maintained system.
Poorly maintained systems can have losses as high as 20 to 30 percent of air capacity and power.