Priming of a centrifugal pump involves fully submerging the impeller in liquid without any air traps before startup. This is required because centrifugal pumps cannot pump air or vapors. Methods to prime centrifugal pumps include manually pouring liquid into the pump, using a vacuum pump to remove air, employing a jet pump to suck water into the pump suction, or installing an air separator to separate liquid and air.

1. Fluid Power Engineering (2151903)
Mechanical Department
Sem.: 5th
D (D2)
• Priming of Centrifugal Pump
• Prepared By: Sajan Gohel(160123119010)
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2. Content
• What is priming?
• Why required of priming?
• Methods of priming.

3. What is priming?
• Priming of a pump is very essential step in start up
of a centrifugal pump. Fact is that centrifugal pump
are not capable of pumping air or vapours.
• Priming is the process in which the impeller of a
centrifugal pump will get fully sub merged in liquid
without any air trap inside. This is especially
required when there is a first start up.

4. Why required of priming?
• The priming of positive displacement pumps is
required only at the time of first starting.
• In this case priming means filling liquid in casing
and aim to diminish the clearance volume.
• It can be removed the air by their own pumping
action. This is called self priming.
• Priming is not required in reciprocating pumps. But
a centrifugal pump is not self priming, thus priming
is required.

5. Methods of priming.
• The pumps can be primed by any of the following
methods.
1.Manually
2.With vacuum pump
3.With jet pump
4.With seperator

6. Manually
• In this method water is poured in the pump through
funnel. When priming is being done, an air escapes
through air vent valve.

7. With Vacuum Pump
• In this method, the small size reciprocating pump is
used priming the main centrifugal pump.
• The suction line of reciprocating pump is connected
to the delivery line of main centrifugal pump.

8. With jet pump
• In this method, water available at high head is
allowed to flow through a nozzle.
• The nozzle is so designed that at the jet outside the
nozzle the pressure is less than the atm pressure so it
is possible to suck water from the sump.

9. With Seperator
• In this method, air seperator is provided on the
delivery side of pump and bent suction pipe portion
is provided at the inlet of the pump.
• Bent suction pipe portion always contain some
liquid.
• The liquid heavier than air, so it falls back into
seperator and air moves in upward direction.
• Therefore the liquid and air are seperated in
seperator.