CENTRIFUGAL PUMP OPERATIONDOE-HDBK-1018/1PumpsSummaryThe important information in this chapter is summarized below.Centrifugal Pump Operation SummaryThere are three indications that a centrifugal pump is cavitating.NoiseFluctuating discharge pressure and flowFluctuating pump motor currentSteps that can be taken to stop pump cavitation include:Increase the pressure at the suction of the pump.Reduce the temperature of the liquid being pumped.Reduce head losses in the pump suction piping.Reduce the flow rate through the pump.Reduce the speed of the pump impeller.Three effects of pump cavitation are:Degraded pump performanceExcessive pump vibrationDamage to pump impeller, bearings, wearing rings, and sealsTo avoid pump cavitation, the net positive suction head available must be greaterthan the net positive suction head required.Net positive suction head available is the difference between the pump suctionpressure and the saturation pressure for the liquid being pumped.Cavitation is the process of the formation and subsequent collapse of vapor bubblesin a pump.Gas binding of a centrifugal pump is a condition where the pump casing is filledwith gases or vapors to the point where the impeller is no longer able to contactenough fluid to function correctly.Shutoff head is the maximum head that can be developed by a centrifugal pumpoperating at a set speed.ME-03Rev. 0Page 16
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