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by Support Support
Jan 10 2022 0 comments

Combination of pumps - Pump curve construction


Parallel Combination 

In parallel pump curves, select some points of the single pump curve head, double the flow in that head, and plot the points. Connect the points in parallel to determine the combined effect of the two pumps. This is shown in Figure 1. 


Fig.1 - Pumps Curve construction for parallel combination

From Figure 2, point A represents the design operating point when both pumps are running, and point B represents the design operating point of the individual pump. 

Fig.2 - Operating points in parallel combinations 

Stand by Operation

One of the major advantages of parallel pumping is standby protection. The function of a standby pump is to continue pumping operation when the first pump becomes inoperative. In parallel pumping, if one of the pumps fails or is out of service, the integrated parallel pump curve disappears, and the point of operation shifts to the intersection of the single pump curve with the system curve already established. This is shown as point C in Figure 3. 


Fig.3 - Stand by Operation

Series Combination 

In series pump curves, select some points of the single pump curve flow rate. Construct this composite curve by doubling the head developed by a single pump at every flow rate as illustrated in Figure 4. 



Fig.4 - Pumps Curve construction for series combination




Fig.5 - Operating points in parallel combinations 

From Figure 5, point a represents the design operating point when both pumps are running, and point b represents the design operating point of the individual pump.