The document compares and contrasts rotary and reciprocating air compressors. Rotary compressors can deliver air at higher volumes up to 3000 m3/min but at lower maximum pressures of 10 bar. Reciprocating compressors deliver lower volumes of around 300 m3/min but at much higher maximum pressures of 1000 bar. Rotary compressors operate at higher speeds continuously while reciprocating compressors operate at lower speeds discontinuously. Hermetically sealed compressors enclose the compressor and motor in a single welded steel casing, making the unit compact and portable. They are commonly used in household appliances like refrigerators and air conditioners that require low power.

1. Thermal Engineering
Production Engineering

2. Rotary & Reciprocating Air Compressor
 Rotary Air Compressor:-
 The maximum delivery pressure for
rotary compressor is 10 bar only.
 The maximum free air discharge
rate is as high as 3000 m3/min.
 Speed of compressor:Speed is
high.
 The supply of air is continuous.
 They are suitable for large
discharge of air at low pressure.
 Executes one step of Rankine cycle.
 Simple lubrication system.
 Reciprocating Air Compressor:-
 The maximum delivery pressure is
as high as 1000 bar.
 The maximum free air discharge
rate is about 300 m3/min.
 Speed of compressor:Speed is
low.
 The supply of air is not continuous.
 They are suitable for low discharge
of air at high pressure.
 Executes the whole Brayton cycle.
 Complicated lubrication system.

3. Advantages Of Rotary Air Compressor Over
Reciprocating Air Compressor.
1. Work faster: Generally, rotary screw air compressors deliver more air
compared to reciprocating compressors of the same size.
2. Work longer: Rotary screw air compressors can operate at 100% duty
cycle.
3. Rotary screw air compressors last longer than reciprocating air
compressors.
4. Rotary screw air compressors are lighter weight and provide more
capacity in a smaller package than reciprocating air compressors.
5. Unlike a reciprocating compressor that loses performance with age,
the rotary screw compressor maintains the same performance
throughout its long life.

4. What is Hermetically Sealed
Compressor?
 In hermetically sealed compressor, the compressor and the motor are
enclosed in the welded steel casing and the two are connected by a
common shaft.
 This makes the whole compressor and the motor a single compact and
portable unit that can be handled easily.
 The hermetically sealed compressor is very different from the traditional
open type of compressors in which the compressor and the motor are
different entities and the compressor is connected to the motor by
coupling or belt.

5. Application of Hermetically Compressor
 A hermetic compressor or hermetically sealed compressor is widely
used in refrigeration or air conditioning applications.
 They are found in household applications such a deep freezers, window
air conditioners and kitchen refrigerators.
 They are hermetically sealed reciprocating compressors with very low
power requirements and easy to handle.

7. Lestest Development In Air Compressor
 Earlier air compressors weighted very much, they were very heavy in
weight, now-a-days, we have ultra modern air compressors which
weighs less.
 Earlier air compressors were not capable of producing or supporting
high capacity, but now, with technology being developed, we have air
compressors like screw air compressors, oil free dental air compressors
etc. which come with increased capacity.