Compressed air regulators are used to lower the pressure or some of it, coming from the receiver of the air compressor and channel it to the correct areas, depending on where the regulator has been fitted. The reason for this is that the pressure of an air compressor can be higher than you need and compressed air regulators can adapt the pressure to suit the application. Compressed air regulators are only able to lower pressure, not increase it.
Whenever the compressor cycle is on, pressure builds up in the system receiver. This can have a detrimental effect on the air compressor as any sudden increases in pressure will produce a pressure-pulse in the compressed air. A receiver will help to dampen the pulse but not entirely. By setting the PSI to 120 on the high side, 100 on the low side and at 90 for entering the application there should not be any fluctuation in pressure.
Compressed air regulators can be either relieving or non-relieving, depending on the application. A non-relieving system would be used for preventing toxic or expensive gas from entering the atmosphere of the plant. Relieving regulators are used for most industrial applications. If the downstream pressure exceeds the pressure setting on the regulator then it is released back into the atmosphere.