Before taking up the actual study of air compressor one must know the important terms which are frequently used in connection with Air Compressor.These terms are most essential because they are the fundamentals of Air Compressor Techonology.One who is interested in air compressor must always remember the following definitions.

01) Air Compressor :- This is the machine which is used to increase the pressure of air by reducing its volume.

02) Reciprocating Compressor :- This is a machine which compresses air by means of piston reciprocating inside the cylinder bore.

03) Single Acting Compressor :- This is a machine which compresses air in only one end of piston and cylinder.

04) Double Acting Compressor :- This is a machine where air is compressed at both end of piston and cylinder.

05) Single Stage Compressor :- This is a machine in which air from atmospheric pressure is compressed upto desired discharge pressure in single operation (stage).

06) Two Stage Compressor :- This is a machine in which air from atmospheric pressure is compressed upto desired pressure in two stages.in first stage air is compressed to an intermediate pressure & in second stage it is further compressed to desired discharge pressure.

07) Multistage Compressure :- This is a compressor in which air is compressed from atmospheric pressure to desired pressure in more than two stages.

08) Rotary Compressor :- This is a machine in which the compression is effected by a rotating vane or impeller that imparts velocity to the flowing air to give it the desired pressure.

09) Inlet Pressure :- This is the absolute pressure of the air at inlet (suction) to a compressor.

10) Discharge Pressure :- This is the absolute pressure of the air at outlet (delivery) of a compressor.

11) Compression Ratio :- This is the ratio of the absolute discharge pressure to the absolute inlet pressure.

12) Free Air Delivery (FAD) :- Free air delivery is the volume of air delivered under the conditions of temperature and pressure existing at the compressor intake.This generally taken as 1.0332 kg/cm square abs & 15 degree centigrate,if air conditions is not given.

13) Capacity of Compressor :- Capacity is the volume of air delivered by compressor.It is generally expressed in cubic feet/min. or meter cube/ min.

14) Theoretical Horse Power :- This is the horse power required to compress adiabatically the air delivered by a compressor through specified pressure range,without any provision for lost energy.

15) Brake Horse Power :- BHP is the actual horse power input reuired by a compressor.

16) Compressor Efficiency :- This is the ratio of theoretical horse power to the brake horse power.

17) Volumetric Efficiency :- This is the ratio of the capacity of a compressor to the piston displacement of compressor.

Prasanna
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