Important terms used in air compressors
An air compressor is a machine used to compress the air and raise its pressure. The compressed air is used for many purposes such as for operating pneumatic drills, riveters, road drills, paint spaying, in starting and supercharging of internal combustion engines, in gas turbine plants, jet engines and air motors etc. It is also utilised in the operation of lifts , rams, pumps and a variety of other devices. In industry, compressed air is used for producing blast of air in blast furnaces and bessemer converters.
The following important terms are frequently used in air compressors:
Inlet Pressure: It is the absolute pressure of air at the inlet of a compressor.
Discharge Pressure: It is the absolute pressure of air at the outlet of a compressor.
Compression Ratio or Pressure Ratio: It is the ratio of discharge pressure to the inlet pressure. Since the discharge pressure is always more than the inlet pressure, therefore the compression ratio is more than unity.
Compressor capacity: it is the volume of air delivered by a compressor and is expressed in cubic meter per minute or cubic meter per second.
Free air delivery: It is the actual volume delivered by a compressor when reduced to the normal temperature and pressure conditions. The capacity if a compressor is generally given in terms of free air delivery.
Swept volume: It is the volume of air sucked by the compressor during its suction stroke.
Mean Effective pressure: It is the ratio if the work done per cycle to the stroke volume of the compressor