System Capacitance Calculation
System capacitance is a measure of how well a system will hold pressure given a certain outflow of air (system demand) without any replenishment.
The main constituent of this capacitance is certainly the receiver tank but the distribution pipeline also plays a major part.
The simplest way to ascertain this value is to measure the time it takes for the pressure in the system to drop when no compressors are loaded.
In the case where a some compressors are loaded then the air flow produced by them should be subtracted from the system demand.
The system demand should either be measured by a flowmeter or be estimated by observing the load of the compressors during this exercise.