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Centrifugal Pump Interview Questions 2 contains questions about Priming in pump, static head in pump, friction head in pump, Centrifugal pump,  High Discharge pump, NPSH for centrifugal pump, NPSH calculate it for a centrifugal pump,  Which pump is more economical than centrifugal pump?, Positive displacement pumps

Frequently asked questions

1. What is priming?

2. What happens to the pressure at the discharge of the pump when the flow increases, or when the discharge valve goes from a fully closed position to fully open?

3. What are the 2 major components of total head?

 4. If you increase the total static head what will happen to the flow?

5. If you decrease the discharge static head, what will happen to the flow?

6. Why the Centrifugal Pump is called High Discharge pump?

7. What is NPSH for centrifugal pump?

8. What NPSH is and how to calculate it for a centrifugal pump?

9. Which pump is more economical than centrifugal pump?

10. Positive displacement pumps are more efficient than centrifugal pump then why Positive displacement pumps are not used in each place?

1. What is priming?

Pump casing must be filled with liquid before the pump is started, or the pump will not be able to function.
 If the pump casing becomes filled with vapors or gases, the pump impeller becomes gas-bound and incapable of pumping.


2. What happens to the pressure at the discharge of the pump when the flow increases, or when the discharge valve goes from a fully closed position to fully open?

It decreases.

3. What are the 2 major components of total head?

Static head and friction head.

 4. If you increase the total static head what will happen to the flow?

It will decrease.

5. If you decrease the discharge static head, what will happen to the flow?

It will increase.

6. Why the Centrifugal Pump is called High Discharge pump?

Centrifugal pump is a kinetic device. 

The centrifugal pump uses the centrifugal force to push out the fluid. So the liquid entering the pump receives kinetic energy from the rotating impeller. 

The centrifugal action of the impeller accelerates the liquid to a high velocity, transferring mechanical (rotational) energy to the liquid. So it discharges the liquid in high rate.

7. What is NPSH for centrifugal pump?

NPSH stands for net positive suction head, for any pump to the design & capacity of pump a net pressure head is required which is called net positive suction head. 

If pressure falls the NPSH, then cavitation will occur. it is net positive suction head to avoid cavitation’s since pressure is below the vapor pressure bubbles forms that cause cavitation’s to avoid these we go for a pressure more than vapor pressure.


8. What NPSH is and how to calculate it for a centrifugal pump?

NPSH is net positive suction head of a pump. For centrifugal pumps,
It is calculated as follows

NPSH = Atmospheric pressure + static head - vapor pressure - pressure loss in the suction piping - pressure loss due to the suction strainer.

9. Which pump is more economical than centrifugal pump?

Rotary pump and Reciprocating pumps are more economical than Centrifugal pump.

10. Positive displacement pumps are more efficient than centrifugal pump then why Positive displacement pumps are not used in each place?

Positive displacement pumps gives more efficiency but

This gives frequent breakdown and increase maintenance cost.

Thanks for reading - Centrifugal Pump Interview Questions 2
Naitik Patel
Industrial Guide

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