Question

Reciprocating air compressor is best suited for
1. large quantity of air at high pressure
2. small quantity of air at high pressure
3. small quantity of air at low pressure
4. large quantity of air at low pressure

Answer 1

Correct Answer - Option 2 : small quantity of air at high pressure

Explanation:

Compressor:

• It is the device which draws air from the atmosphere and compressed to the required pressure.

Compressors are of two types:

1. Positive displacement type Compressor:
   • Positive displacement type like reciprocating compressors, Root's blower, and vane - sealed machines.
   • For air at very high pressure, we require the reciprocating compressors.
   • The only disadvantage with reciprocating compressor is a low supply of air.
2. Rotary type Compressor:
   • Rotary type like centrifugal and axial flow compressor.
   • Rotary compressors are best suited for a large quantity of air at low pressure.

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	The 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	A large measure of air can be handled and it is about 500 m3/s
3	Speed of Compressor	Low speed of the compressor	High speed of the compressor
4	Vibrational Problem	Due to the reciprocating section, greater vibrational problem, the parts of the machine are poorly balanced	Rotary parts of the machine, thus it has less vibrational problems. The machine parts are balanced
5	Size of compressor	Size of Compressor is bulky for given discharge volume	Compressor size is small for given discharge volume
6	Suitability	For medium to the high-pressure ratio For low and medium gas volume	For low to medium pressures For large volumes