A rotary vane compressor always compresses the gas the design pressure defined by the manufacture, regardless of the pressure in the system in which the compressor is discharging.

This is a positive-displacement pump that consists of vanes mounted to a rotor that rotates inside a cavity.

The vane-type compressor consists of a cylindrical rotor with longitudinal slots in which radial sliding vanes are fitted.

The rotor is positioned eccentrically within a cylindrical housing.

The spaces between adjacent vanes form pockets of decreasing volume from a fixed inlet port to a fixed discharge port.Compressor inlet and discharge valves are not employed in the design.

Rotary compressors are another type of famous compressor. It uses two Asymmetrical rotors that are also called helical screws to compress the air.

The rotors have a very special shape and they turn in opposite directions with very little clearance between them.

The rotors are covered by cooling jackets. Two shafts on the rotors have been placed that transfer their motion with the help of timing gears that are attached at the starting point of the shafts/compressor (as shown in the image).Air sucked in at one end and gets trapped between the rotors and gets pushed to another side of the rotors.

The air is pushed by the rotors that are rotating in the opposite direction and compression is done when it gets trapped in clearance between the two rotors. Then it pushed towards the pressure side.

Rotary screw compressors are of two types oil-injected and oil-free. Oil-injected is cheaper and most common than oil-free rotary screw compressors.