At what speed, when pumping water, should the 105 cm pump of the figure below run to realize, at highest efficiency, (a) a head of 30 m? For this condition, what are the resulting (b) flow rate, and (c) brake horsepower? n=710 r/min 120 7.5 NPSH 6.0 105 105-cm dia. 4.5 3.0 96.5-cm dia. 75 89-cm dia. 86% 84% 60 45 1000 bhp 30 15 30 45 60 75 90 105 00 m/min NPSH, m 1500 bhp 1250 bhp %88 %68 %98 %08 %09 Total head, m

Two reservoirs, A and B, are connected together by the two pipes with a pump between them. Assuming that the head loss in the pipes is given by hi = 0.015(L/d)(V/2g), where "L" is the length of pipe in feet and "d" is the pipe diameter in feet, determine (a) the velocity in each pipe, (b) the head added by the pump, and (c) the horsepower that must be supplied to the water to pump 2.5 cfs from the lower to the upper reservoir? El 140 ft B A El 90 ft L: = 2000 ft d: = 8 in. El 40 ft --- L; = 1000 ft d: = 8 in.

Determine the shaft horsepower for an 80% efficient pump to discharge 30L/s through the system. The system losses, exclusive of pump losses, are 12V2/2g and H = 16m. Ans: 8.75hp H 150mm dia