Smart strategies can allow rotary screw air compressors to be used effectively and efficiently, so that they are not running at full power even when the air is not in demand.

Ron Marshall of the Compressed Air Challenge, a voluntary industry initiative to improve air compressor performance, writes for the Fluid Power Journal of the various ways in which this can be achieved.

He explains: “Rotary screw compressors often operate in systems where the whole capacity of one or more compressors is not required all the time.

“When an air compressor is partly loaded, some method of control is required to unload the compressor.”

For instance, load/unload control, also known as online/offline control, simply sets the air compressor to be active for a certain percentage of the time.

An alternative is for it to switch on, or load, at one pressure, and switch off again, or unload, at a specific higher pressure – thus keeping the supply within, for example, a 10 psi range.

More advanced controls are becoming available too, and it can be important to shut off the supply in a closed system, to avoid overloading it with compressed air.

But the best strategy for doing so can depend on the system itself – and making the right choice is key to getting the best from your rotary screw air compressors.