positive-displacement compressor

A positive-displacement compressor is a machine that increases the pressure of a gas by decreasing its volume. In this type of compressor, gas is drawn into a chamber during a suction stroke. As the piston moves in the opposite direction, the volume decreases, compressing the gas. The compressed gas is then discharged when its pressure exceeds that of the outlet valve. Reciprocating piston compressors are particularly useful for delivering small volumes of gas at high pressures. Pumps that use mechanical displacement are called positive displacement pumps, and they generally move low volumes of fluid at high pressure.12