Pumping Systems:

Net Positive Suction Head and Its Significance?

.npsh

What is an NPSH curve and what is its significance?

Answer:

The NPSH curve displays the minimum required inlet pressure (expressed in m) allowing the pump to pump ir

accordance with the performance curve and in order to prevent evaporation of the pumped fluid so as to avoid cavitation inside the pump.

At a given flow rate, the NPSH value available at the pump’s suction ports must always be at least 0.5 m

greater than the required NPSH value: NPSHA > NPSHR + 0.5 m safety margin.

Operating a centrifugal pump below the NPSH curve can cause cavitation, which can damage the pump and reduce its efficiency. When a pump is operating below the NPSH curve, it means that the Net Positive Suction Head Available (NPSHA) is less than the Net Positive Suction Head Required (NPSHR). This can cause the fluid to boil and form bubbles, which can collapse when they reach areas of higher pressure, causing damage to the impeller and other components of the pump.

The NPSHA is affected by factors such as fluid temperature, fluid density, and suction piping configuration. If the NPSHA is too low, it can be increased by increasing the pressure at the suction port of the pump or by reducing the temperature of the fluid.

It is important to operate a centrifugal pump within its NPSH limits to prevent cavitation and ensure optimal performance. If you are operating a centrifugal pump below its NPSH curve, you should take steps to increase the NPSHA or reduce the flow rate to avoid cavitation.