Machine for increasing the pressure of a gas by mechanically decreasing its volume.
Air is the most frequently compressed gas, but natural gas, oxygen, nitrogen, and other industrially important gases are also frequently compressed. There are three general types of compressors. Positive-displacement compressors are usually of the reciprocating piston type (see piston and cylinder ), useful for supplying small amounts of a gas at relatively high pressures. Centrifugal compressors are particularly suited for compressing large volumes of gas to moderate pressures. Axial compressors are used for jet aircraft engines and gas turbines.