An air compressor is a device used to compress atmospheric air taken in through inlet valves and compressed to a high pressure, the compressed air being used for various purposes such as cleaning, spray painting, pneumatic operations, starting the main engine, etc. Air compressors force air into a tank, increasing its pressure. When the tank pressure reaches its predetermined value, the compressor shuts off automatically. The compressed air is held in the tank until it is used.
Air compressors are classified thus:
According to the pressure delivered:
- Low Pressure Air Compressors which have a discharge pressure of 150 psi or less.
- Medium Pressure Air Compressors which have a discharge pressure of 150 psi to 1000 psi.
- High Pressure Air Compressors which have a discharge pressure of 1000 psi and above.
According to the design and principle of operation.
- Single Stage Reciprocating compressors
- Multi Stage Reciprocating Compressors
- Compound Compressors
- Rotary Screw Compressors
- Scroll Compressors
- Turbo Compressors
- Centrifugal Compressors
Two types of Compressors are:
1 Positive Displacement Compressors
2 Roto-Dynamic Compressors
Positve Displacement Compressors
These Compressors work by forcing air in a chamber whose volume is decreased to compress the air. Once the maximum pressure is reached, a port or valve opens and air is discharged into the outlet system from the compression chamber. Examples of positive displacement Compressors are piston type, rotary screw and vane air Compressors.
Roto-Dynamic Air Compressors
In these compressor types, a rotating component imparts its kinetic energy to the air which is eventually converted to pressure energy. The compressor uses centrifugal force generated by a spinning impeller to accelerate and then decelerate captured air which pressurizes it. Examples of these Compressors are, centrifugal and axial Compressors.