Description
8
P1700040
3.4 Function
3.4.1 Principles of Vacuum Pump Operation
The main purpose of a vacuum pump is to reduce the pressure in a vessel or a closed system. The
degree of pressure reduction is dependent upon the requirements of the application and the type of
vacuum pump employed.
3.4.2 Working Principle of Rotary vane pumps
Pressure reduction in a closed system is accomplished by repeatedly removing a portion of the
original volume of gas contained in the system. Removal is performed by the action of the rotating
elements of the pump which cause a given space to be successfully enlarged and diminished. Figure
2 illustrates a chapter through a typical stage of rotary-vane pump. Note that this figure is not intended
to illustrate exactly the internal components of the pumps; its purpose is to illustrate the general
operating principles of vacuum pumps.
Fig. 2 Rotary vane pump Principle
The rotary action of the pump creates a hollow space of chamber (1) which expands as the pump
rotates. As the chamber expands, the pressure in the chamber decreases. As a result, gas is drawn
into the chamber due to the difference in pressure between the chamber and the inlet (4) to the
chamber (The inlet is the only place where gas can flow into the chamber). Once the vane (3) moves
past the inlet (4), it seals the inlet against the chamber (1) and the gas becomes trapped between the
vanes (2 and 3). The chamber (1) formed by the enclosed space between the vanes then begins to
decrease in volume as the rotor revolves, compressing the gas. The pressure of the compressed gas
becomes greater than atmospheric pressure. When the vane (2) moves past the exhaust port (5) the
compressed gas in the chamber is forced out through the exhaust port. This expansion/compression
cycle constitutes one complete cycle of the pump operation. This cycle is repeated as the vane (2)
passes the intake port and seals it against the atmosphere. Therefore, two pump cycles are performed
during each revolution of the pump rotor.
3.4.3 Working Principle of Two-Stage Rotary vane pumps (CRVpro Series)
