There are there performance characteristics of pump:
Head developed by the pump (H)
Brake horse power (BHP)
Efficiency of the pump
-all plotted against the flow rate.
(Fig. 25b)
As seen from the graph, head decreases with increasing flow rate till the pump cannot deliver the fluid at . Horsepower increases with flow rate. Efficiency of the pump initially increases with increasing flow rate, reaches a maximum, and then decreases to zero at . Pump is operated at .
. Horsepower increases with flow rate. Efficiency of the pump initially increases with increasing flow rate, reaches a maximum, and then decreases to zero at 
.
