PUMPS - TYPES & OPERATION - Centrifugal Pump: the casing PDF Print E-mail
Written by Norrie   
Saturday, 27 March 2010 14:10
Article Index
PUMPS - TYPES & OPERATION
CENTRIFUGAL PUMPS
Centrifugal Pump: the rotor
Centrifugal Pump: the casing
Prime Movers
CHARACTERISTICS OF CENTRIFUGAL PUMPS
The Valves of a Centrifugal Pump
CENTRIFUGAL PUMP OPERATION
CENTRIFUGAL PUMPS - FLOW & PRESSURE
Cavitation
AIR BINDING IN A CENTRIFUGAL PUMP
POSITIVE DISPLACEMENT PUMPS
OTHER TYPES OF ROTARY PUMPS
RECIPROCATING (PISTON) PUMPS
SINGLE ACTING RECIPROCATING PUMPS
DOUBLE ACTING RECIPROCATING PUMPS
Advantages & Disadvantages of Piston Pumps
All Pages

PART 2. THE CASING

This is the stationary part of the pump and includes the :

  1. Suction Nozzle(s) (or Port(s)).
  2. Discharge Nozzle (or Port).
  3. Bearings.
  4. Seals.

(The casing of a multi-stage centrifugal pump is very similar to that of a multi-stage compressor having diaphragms with diffusers & return passages. However, as liquids are non-compressible, the stages do not become progressively narrower).

The 'Volute' casing. This is named from the spiral shape of the casing which is so constructed to act as a collector for the liquid as it leaves the outer edge of the impeller vanes.

The liquid at this point is at high velocity. As the liquid enters the volute, the velocity is decreased. This causes an increase in pressure which is the objective of the pump. (Increased pressure is increased energy).

(See Figure: 21)

Figure: 21 - Volute Type Casing

Earlier, the types of bearings and their purpose was discussed as was the types of seals and their purpose.

Briefly, the purpose of bearings is to support the weight of the rotor and to minimise radial and axial movement and therefore, vibration.

Seals are used to prevent leakage of fluid to atmosphere and/or between the stages of a multi-stage machine.



Last Updated on Saturday, 27 March 2010 15:27