Compressed air is used for numerous applications, naturally, the basis of a compressor installation is the compressor itself. This compresses ambient air up to the required delivery pressure.
Figure 10.4.1.1
Within a compressed air system, it is the primary task of the compressed air receiver to even out pressure fluctuations occurring in the system.
Diagram 10.4.1.1
If the effective volume flow generated by the compressor is greater than the actual air consumption, the compressor, sensed by a pressure monitor, switches over to idle running or non-running for a certain time interval, depending on the selected mode of operation. During this period, the unwanted compressor output does not cause a pressure rise in the system. When maximum operating pressure is reached, the compressed air receiver supplies compressed air to points of use, until the lower switch-on point of the pressure system has been reached. The receiver size needed for a compressed air system is calculated or taken from appropriate diagrams. The receiver design in Diagram 10.4.1.1 is based on a load factor of a = 50%, the consumption is half the amount of the volume flow of the compressor. The receiver volume can be calculated in accordance with the following formula :
Formula 10.4.1.1
Here Q = receiver volume in m3 and V = volume flow m3/min. Values z = number of switching cycles and dp = pressure difference. With a = 50%, switching frequency for the compressor motor is at its highest. Once the actual loading is known, the receiver volume can be reduced by the factor f. It is often desirable to use a pressure vessel to cope with short periods of peak demand at specific points in the network. In such cases it is not always expedient to place the receiver next to the compressor but, instead place it near the point of use. The compressed air is taken to the points of use via the piping system.
