Commonly used air compressors include piston-type, screw-type (which are further subdivided into twin-screw and single-screw variants), centrifugal, rotary vane, and scroll compressors. The definitions for these various compressor types are provided below. Certain other compressor types-Such as cam, diaphragm, and diffusion pumps-have been omitted from this list due to their specialized applications and relatively compact dimensions.
Positive Displacement Compressor-A compressor that increases gas pressure by directly altering the volume occupied by the gas.
Reciprocating Compressor-A type of positive displacement compressor in which the compression element is a piston that undergoes reciprocating motion within a cylinder.
Rotary Compressor-A type of positive displacement compressor in which compression is achieved through the forced motion of rotating elements.
Rotary Vane Compressor-A type of rotary positive displacement compressor in which axial vanes slide radially within a rotor that is mounted eccentrically inside a cylindrical casing. The air trapped between the vanes is compressed and subsequently discharged.
Liquid-Ring Compressor-A type of rotary positive displacement compressor in which water or another liquid acts as a piston to compress and subsequently discharge the gas.
Roots Blower (Twin-Lobe Compressor)-A type of rotary positive displacement compressor in which two intermeshing Roots-type rotors trap the gas and transport it from the inlet port to the outlet port. No internal compression occurs within this type.
Screw Compressor-A type of rotary positive displacement compressor in which two rotors featuring helical lobes intermesh to compress and discharge the gas.
Dynamic Compressor-A type of rotary compressor utilizing a continuous gas flow, in which high-speed rotating blades accelerate the gas passing through them, thereby converting kinetic energy into pressure energy. This energy conversion occurs partially within the rotating blades themselves and partially within stationary diffusers or return vanes.
Centrifugal Compressor-A type of dynamic compressor featuring one or more rotating impellers (typically equipped with blades on their periphery) that accelerate the gas. The primary gas flow is radial in direction.
Axial Compressor-A type of dynamic compressor in which the gas is accelerated by a rotor fitted with blades. The main airflow is axial.
Mixed-flow compressors-Also classified as dynamic compressors-feature rotors whose geometry combines characteristics of both centrifugal and axial designs.
Jet compressors-Utilize a high-velocity jet of gas or steam to entrain the intake gas, subsequently converting the velocity of the mixed gas stream into pressure within a diffuser.
