Difference between positive displacement pump and centrifugal pump [with Pdf]

The difference between the positive displacement pump and centrifugal is that the centrifugal pump accelerates the liquid because of the centrifugal force generated by the impeller while the positive displacement pump moves or pushes a certain amount of liquid in a repeated manner.

positive displacement pump vs centrifugal

Before understanding the difference, let’s see briefly about the centrifugal and positive displacement pump.

What is centrifugal pump:

  • It is a rotating machine that converts the kinetic energy of the shaft into the hydrodynamic energy of the fluid.
  • The working of a centrifugal pump is based on the principle of centrifugal force.
  • The common components of a centrifugal pump are rotor, impeller, and casing.
  • It has a large number of applications for domestic and industrial purposes.

What is positive displacement pump:

Gear pump
  • The pump which moves a certain amount of liquid in a repeated manner is the positive displacement pump.
  • The positive displacement pump gives low discharge with high pressure.
  • It is generally used in applications where the high pressure of the fluid is required.
  • Some of the types of positive displacement pumps are,

1) Reciprocating pump:- piston pump, diaphragm pump, etc
2) Rotary pump:- gear pump, vane pump, screw pump.

Positive displacement pump and Centrifugal pump

Sr. No. Positive displacement pump Centrifugal pump
1It pumps the liquid by continuously displacing a certain amount of liquid.The fluid is displaced due to the centrifugal action.
2The flow rate remains constant for any change in pressure.The fluid flow rate changes with a change in pressure at the output.
3Some of the positive displacement pumps give fluctuating discharge (reciprocating) while some pumps give continuous discharge (gear pump).It gives continuous discharge.
4It is used to obtain a higher head with a lower discharge rate of the fluid.The pump provides a high discharge rate with a low head.
5It handles a small quantity of liquid.It handles a large amount of liquid.
6It handles less viscous fluids.It can easily handle viscous fluid with the same flow rate.
7If the discharge valve is kept closed while running then the pump or motor may damage.If the discharge valve is kept closed while running condition then there will be nothing damage will happen to the pump.
8There is no need for priming while starting the pump.It requires priming.

So, We have covered all significant points for the difference between positive displacement pump and centrifugal pump, Thanks for the reading. Hope you liked it. Share with friends and spread the knowledge.

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