Fluid FlowCENTRIFUGAL PUMPSThe system has a flow rate equal to and a total system head loss equal to DPo. In order toVomaintain the flow rate , the pump head must be equal to DPo. In the system described by(Vo)the system curve (hL1), a valve has been opened in the system to reduce the system’s resistanceto flow. For this system, the pump maintains a large flow rate at a smaller pump head(V1)(DP1).SystemUseofMultipleCentrifugalPumpsA typical centrifugal pump has a relatively low number of moving parts and can be easilyadapted to a variety of prime movers. These prime movers include AC and DC electric motors,diesel engines, steam turbines, and air motors. Centrifugal pumps are typically small in size andcan usually be built for a relatively low cost. In addition, centrifugal pumps provide a highvolumetric flow rate with a relatively low pressure.In order to increase the volumetric flow rate in a system or to compensate for large flowresistances, centrifugal pumps are often used in parallel or in series. Figure 11 depicts twoidentical centrifugal pumps operating at the same speed in parallel.CentrifugalPumpsinParallelFigure 11 Pump Characteristic Curve for Two Identical Centrifugal Pumps Used in ParallelSince the inlet and the outlet of each pump shown in Figure 11 are at identical points in thesystem, each pump must produce the same pump head. The total flow rate in the system,however, is the sum of the individual flow rates for each pump.Rev. 0 Page 53 HT-03
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