Comparison Between Reciprocating and Rotary Compressors

Comparison between Reciprocating and Rotary Compressors can be done in aspects like pressure ratio, handled volume, speed of compressor, vibrational problem, size, air supply, purity of compressed air, compression efficiency, maintenance, mechanical efficiency, lubrication, initial cost, flexibility and suitability.

S.no	Aspect	Reciprocating Compressors	Rotary Compressors
1	Pressure Ratio	Discharge Pressure of air is high. The pressure ratio per stage will be in the order of 4 to 7.	Discharge pressure of air is low. The pressure ratio per stage will be in the order of 3 to 5.
2	Handled Volume	Quantity of air handled is low and is limited to 50m³/s.	Large measure of air handled can be handled and it is about 500 m³/s.
3	Speed of Compressor	Low speed of compressor.	High speed of compressor.
4	Vibrational Problem	Due to reciprocating section, greater vibrational problem, the parts of machine are poorly balanced.	Rotary parts of machine, thus it has less vibrational problems. The machine parts are fairly balanced.
5	Size of compressor	Size of Compressor is bulky for given discharge volume.	Compressor size is small for given discharge volume.
6	Air supply	Air supply is intermittent.	Air supply is steady and continuous..
7	Purity of compressed air	Air delivered from the compressor is dirty, since it comes in contact with lubricating oil and cylinder surface.	Air delivered from the compressor is clean and free from dirt.
8	Compressed efficiency	Higher with pressure ratio more than 2.	Higher with compression ratio less than 2.
9	Maintanence	Higher due to reciprocating engine.	Lower due to less sliding parts..
10	Mechanical Efficiency	Lower due to several sliding parts..	Higher due to less sliding parts.
11	Lubrication	Complicated lubrication system.	Simple lubrication system.
12	Initial cost	Higher.	Lower.
13	Flexibility	Greater flexibility in capacity and pressure range.	No flexibility in capacity and pressure range.
14	Suitability	For medium and high pressure ratio. For low and medium gas volume.	For low and medium pressures. For large volumes.

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