Water at 20C is being pumped from a lower to an upper reservoir through an 8 in Schedule 40 pipe in the system shown the Figure. The water-surface elevations in the source and destination reservoirs differ by 48 ft, and the length of the steel pipe connecting the reservoirs is 230 ft. The pump is to be located 9.5 ft above the water surface in the source reservoir, and the length of the pipeline between the source reservoir and the suction side of the pump is 35 ft. The desired flow rate in the system is 500 gpm. The discharge line contains four 90 elbows and I gate valve.

(a) If the overall efficiency of the pump and the motor driving it is 80% and the cost of electric energy to the motor is Php 2.50 per kW-hr, what is i the hourly energy cost for pumping this water?

(b) Would you expect a cavitation problem for this piping system? The required NPSH is 15 ft.

DZ Pump