This document discusses different types of compressors used to compress air or gas. It describes reciprocating compressors which use pistons driven by cranks to compress air in cylinders. Rotary compressors are also discussed, including roots blowers which use two meshing lobes to trap and compress air, and vane compressors which use vanes in a rotor to vary chamber sizes and compress air. Various uses of compressed air are listed such as for pneumatic tools, spraying, and operating machinery. Compressors are classified based on their compression method, pressure level, stage number, cylinder number, capacity, and type of fluid compressed.

4. INDEX
1.1 Introduction
1.2 Uses of Compressed air
1.3 Reciprocating compressor
1.4 roots blower compressor
1.5 vane type compressor

5. Introduction
• The machine which takes in air or any other gas at
low pressure and compresses it to high pressure are
called compressors.
• They are power consuming machines in which
mechanical work is converted into the pressure head
of air or gas.
• They are also considered as reversed heat engine.
• Generally, the compressors are driven by electric
motors, I.C. engine or gas turbines.
• A compressor is used for increasing the pressure of
air is called air compressor.

6. Classification of compressors
(1) Method of compression
• Reciprocating compressors:.
• Rotary compressors:
• Centrifugal compressors
(2) Delivery pressure
• Low pressure
• Medium pressure
• High pressure
• Very high pressure

7. (3) Principal of operation
Positive of displacement
Rotodynamic or steady flow compressor
(4) The number of stages
Single stage compressor - pressure up to 5 bar
Multistage compressor - pressure above 5 bar
(5) The number of cylinder
Single cylinder
Multi cylinder

8. (6) Volume of air delivered
• Low capacity
• Medium capacity
• High capacity
(7) Fluid to be compressed
• Air compressor
• Gas compressor
• Vapour compressor

9. Uses of compressed air
In refrigeration cycle
Operation tools like drill hammers etc.
Filling the air in automobile tyres
Spray painting
Increasing inlet pressure of I.C. engine
To operate air motor I mines where fire risk are more
Pumping water
Gas turbine power plant
Conveying the materials like sand and concrete along a
pipe line
For sand blasting
Operating blast furnace
Operating air brakes used in buses truck trains etc.

10. Reciprocating compressor
 A single stage reciprocating compressor. It used for
compressing air and it is satisfactory for all ranges of pressure
it consist of the cylinder in which a piston reciprocates the
piston is driven by crank through connecting rod .the crank is
mounted in a crank case. the value are generally pressure
differential type.

12. Rotary compressor

13. (1) Roots Blowers
• The roots blower consists of two lobe For higher
pressure ratio three and four lobes may be used here
the pressure of air delivered is slightly above the
atmosphere.
• The machine consists of a fixed casing two shafts
fitted with two lobe rotors one of the rotor is driven
by electric motor or other prime movers and other is
driven through the gears from first.

14. • The air is drawn through the inlet pipe due to rotation
of due rotors. the volume of air is entrapped between
one rotor and casing for a very short interval due to
rotation of lobe trapped air is carried to the discharge
side continued rotation of rotors open the trapped
space to the discharge port. the air is pushed to the
receiver due to the continued rotation of rotors.

15. (2) Vane type compressor
• This type of compressor is shown inn fig. The compressor
is consists of rotor drum mounted eccentrically in the
cylindrical casing. The rotor is provided with vanes in the
slots. These vanes or blades are made from non-metallic
material usually fiber or carbon.
• The vanes can slide in and out in the slots. The volume
between two vanes keeps on
changing due to eccentric motion
of the rotor. The rotation of the
rotor causes space to be created between
the vanes,the rotor and casing.The
space is connected to suction pipe so
that air enters into the created space
and filled.

16. • A volume V1 of air trapped between the vanes and casing. With the rotation
of rotor of rotor, air gets compressed due to reduction of space towards
delivery side.
• The fluid volume reduces to V2,when it communicates with the delivery
side. Since the receiver pressure is higher than the compressed air between
the vanes, the back flow of air from the receiver will take place.
• Due to rotation of vanes air is delivered to the receiver. In this type of
compressor. the total pressure rise is partially due to internal compression
between the vanes and partially due to back flow of air from receiver.
• This type of compressor can produce a pressure ratio up to 6 per stage