What is a compressor? Types of compressor and definition

Types of compressor

Air compressor

Compressor can be defined as a device that increases the pressure of the gasses by compressing them in an enclosed chamber.As gasses are compressible, the compressor also reduces its volume.  The high-pressure gas after compression can be transported then to the required place.Types of the compressor

Types of compressor and their details

types of compressor

Compressors are divided into two main categories based on their working principle:

  1. Positive displacement compressors
  2. Dynamic compressors

These are further divided into subcategories as indicated below:

Positive displacement compressors

Positive displacement compressors are those which displace the intake gas from one volume condition to the other volume condition with the help of certain mechanism to increase the pressure of the gas. These type of compressors supply compressed gas in batches.

-Reciprocating compressors

Reciprocating compressors

Reciprocating compressors use crank-lever mechanism to convert the rotational motion of the shaft into reciprocating motion of the piston to compress the gas. It can be powered by an engine or electric motor. They provide a high compression ratio with a low flow rate.

Applications of reciprocating compressors are in beverage and food, oil & gas, automotive and refrigeration industries etc.

Reciprocating compressors have further three types

Single Acting:In single-acting, the compression of gas takes place only in one direction.
Double Acting:In double-acting compressor, the compression takes place in both the directions of the piston.
Diaphragm:The diaphragm compressor has a flexible membrane which is linked with the reciprocating mechanism to do the process of compression with the help of membrane. It is also known as membrane compressor.

-Rotary compressors

Rotary compressors are a type of positive displacement compressors which use rotary parts to compress the gas. They are lighter and less vibratory than the reciprocating compressors. Applications of Rotary compressors are in industries where a continuous flow of compressed gas is required like packaging and manufacturing industries etc.

Rotary compressors have further five types

Screw compressor

Screw compressors:Rotary screw compressors consist of rotating screws which mesh together compressing the gas to provide a continuous supply of compressed gas. They can be oil-free or use lubrication for working.

Scroll compressors:Scroll compressors usually have two spiral vanes out of which one is fixed and other is rotating. The gas enters radially and leaves out the compressor axially at the center. Scroll compressors are used in air-conditioning systems and heat pumps

Lobe compressors:Rotary lobe compressors consist of two lobes rotating in opposite direction to intake and compress the gas between the two rotating lobes and the casing.

Vane compressors:Vane compressors use a rotating cylinder with slots providing moveable vanes. The rotation changes the condition of the compressor from the maximum volume at the input to minimum volume conditions at the output. They are low cost and have compact dimensions.

Liquid Ring compressors:Liquid Ring compressors are like rotary vane but have vanes as an integral part that uses the liquid to create a vacuum to intake gas and then deliver it at high pressure at the out port. The liquid remains within the chamber.

Dynamic compressors

Dynamic compressors compress the gas by the rotating part at high speed to increase the pressure head of the gas. They are continuous flow devices providing a large volume of compressed gas.
Applications of dynamic compressors are where the high flow rate is required like chemical, petroleum, power plants and process industries.

Dynamic compressors have further two types


Centrifugal compressor has an impeller and a diffuser. The rotating impeller compressed the gas with the vanes against the diffuser wall to create high pressure. These type of compressors find applications in process industries mostly.


Axial compressors have a radial shaft with vanes that decrease in diameter along the length of the shaft to compress the gas. They provide high flow rates.

Types of compressor

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