Isolate the compressor along with its individual receiver that are to be taken for a test from the main compressed air system by tightly closing the isolation valve or blanking it, thus closing the receiver outlet.
Open the water drain valve and drain out water fully and empty the receiver and the pipeline. Make sure that the water trap line is tightly closed once again to start the test.
Start the compressor and activate the stopwatch.
Note the time taken to attain the normal operational pressure P2 (in the receiver) from initial pressure P1.
Free Air Delivery is to be
corrected by a factor (273 + t1) / (273 + t2)
Calculate the capacity as per the below formula given.
Where,
P2 = Final pressure after filling (kg/cm2a)
P1 = Initial pressure (kg/cm2a) after bleeding)
P0 = Atmospheric pressure (kg/cm2a)
V = Storage volume in m3 which includes receiver, after cooler and delivery piping
T = Time take to build up pressure to P2 in minutes