Fixed Speed Rotary Screw Compressors

In a load/unload control scheme, the compressor remains continuously powered. However, when the demand for compressed air is satisfied, instead of disconnecting power to the compressor, the inlet valve is closed, unloading the compressor. This reduces the number of start/stop cycles fir electric motors over a start/stop control scheme in electrically-driven compressors improving equipment service life with minimal change in operating cost.


This scheme is utilised by nearly all industrial air compressor manufacturers. When a load/unload control scheme is combined with a timer to stop the compressor after a predetermined period of continuously unloaded operation, it is known as a dual control or auto-dual scheme.

GA 5-11

GA 11 +30

GA 15-22
An image of the 2016 upgrade of the GA30+ Fixed Speed Compressor

GA 30+45

The new compressors launched by Atlas Copco offer significant energy savings



GA 200-500


GX2 – 11

Two of the models in the new F-Series of refrigerant dryers from Atlas Copco

G 7-15