Pumps are machines driven by an external power to provide energy (force) to fluids. There are three types’ namely positive displacement pumps, negative displacement pumps or centrifugal pumps and ejector pumps.
Example for positive displacement pumps are force pumps, lift pumps, bucket and plunger pumps, rotary pumps etc.,
SIMPLE FUNCTION OF A FORCE PUMP
A solid piston or plunger which moves within a cylinder up & down by means of push pull actions. As a result it creates a suction stroke, which is used to lift the water from ground level.
An inlet valve and outlet valve is fixed along with the cylinder and when piston moves upward, inlet valve opens & outlet valve is closed similarly when piston moves downward, inlet valve closed & outlet valve opens.
NEGATIVE DISPLACEMENT PUMPS OR CENTRIFUGAL PUMPS
Examples for centrifugal pumps are single stage centrifugal pumps, two stage centrifugal pumps, multi-stage centrifugal pumps.
It consists of two main parts, the impeller & the casing. Impeller provides a high velocity to the water / fluids whereas the casing transforms these velocities in to pressure energy.
Casing inner walls contains guide vanes which is used to reduce the turbulence and also known as the guide rings or diffuser.
ADVANTAGES OF CENTRIFUGAL PUMPS
Moving parts are very less, therefore wear /tear is less.
It ensures continues flow of water.
It construction was very simple
DISADVANTAGES OF CENTRIFUGAL PUMPS
Priming is necessary, they are not self-priming.
Two stage centrifugal means two impellers mounted on one shaft with extended guide vanes.
EJECTOR PUMPS – ADVANTAGES
No moving parts, therefore no wear / tear loss.
Light weight, easy to handle.
Low maintenance is required.
They can be used in anywhere.
PRIMERS
The primers is a separate device provided either manually or automatically , depending upon the type of centrifugal pump, and it is used to eliminate the air from suction hose and pump casing.
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