Concept of NPSH in pump
Net Positive Suction Head or NPSH represents the suction head at the pump impeller eye. It represents the head required to make the fluid flow from the suction pipe to pump impeller.
For a smooth and cavitation free performance of the pump, NPSH Net Positive Suction Head must be positive and should have a value that the flowing fluid does not change under reduced pressure.
Higher suction lift, higher temperature of the fluid, higher losses in pipelines, all these tend to reduce available NPSH Net Positive Suction Head.
Pump designer give us the NPSHR (equired) usually depending upon the test results of the actual pump. It is necessary that the available NPSH must be higher or equal to NPSHR.
NPSH calculation for suction lift
NPSH calculations help us to
- Reduce cavitations.
- Maintain pump functionality and longevity.
- Characteristic of the process suction system.
- An analysis of total energy on the suction side of a pump to determine whether the liquid will vapourize at a low pressure point in the pump.
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