Positive Displacement Type of Pump

Question

Explain why the Centrifugal Pump is not known as the Positive Displacement Type of Pump?

Answer 1

Centrifugal has varying flow depending upon the pressure or the head; on the other hand, flow in the Positive Displacement pump is more or less constant regardless of the pressure.

Similarly, the viscosity is constant for the positive displacement pumps whereas, value of the centrifugal pump is up and down because higher viscosity liquids fill the clearances of pump resulting in a higher volumetric efficiency. Whenever there occurs a viscosity change in the supply there occurs greater loss within the system. This means change in the pump flow is affected through the change in pressure.