Rotary air compressors are a family of compressors in which air is drawn into spaces formed between the rotating lobes in the rotor and the casing of the compressor. The lobes are designed that they form an air tight pocket with the casing. The lobes are usually screw shaped. The screw shaped rotating lobes mesh with each other to form a pocket in which the gas travels. The air is pushed towards the outlet of the compressor. The gas or the air is thus compressed.
Rotary air compressors are used where large quantities of compressed air are required.
Unlike the reciprocating compressors, where the compression occurs in cycles, the flow in a rotary compressor is steady and continuous. This reduces pulsation in the gas.