What is the meaning of NPSHr for centrifugal pump?
NPSHr is meaning there will result in gas when the transferred liquid flow to centrifugal pump inlet because of the certain vacuum pressure. The bubble will corrode the impeller and other parts metal surface, under the impact of the liquid particle. Then will damage the impeller or other metal parts. This vacuum pressure is named vapour pressure. NPSHr is the pressure drop to lowest pressure point from pump inlet. The unit is meter. It determined by the centrifugal pump itself.
The value is lower, the pump inlet resistance loss less. So, the NPSHr is the minimum value of NPSH. For example, when selected use slurry pump, the NPSHr must meet the requirement of the delivered liquid feature and installation condition.