Repeat Prob. 14–58E, but at a water temperature of 113°F. Discuss.

Data from Prob. 14–58

A centrifugal pump is used to pump water at 77°F from a reservoir whose surface is 20.0 ft above the centerline of the pump inlet (Fig. P14–58E). The piping system consists of 67.5 ft of PVC pipe with an ID of 1.2 in and negligible average inner roughness height. The length of pipe from the bottom of the lower reservoir to the pump inlet is 12.0 ft. There are several minor losses in the piping system: a sharp-edged inlet (K_L = 0.5), two flanged smooth 90° regular elbows (K_L = 0.3 each), two fully open flanged globe valves (K_L = 6.0each), and an exit loss into the upper reservoir (K_L = 1.05). The pump’s required net positive suction head is provided by the manufacturer as a curve fit: NPSH_required  = 1.0 ft + (0.0054 ft/gpm²)V̇², where volume flow rate is in gpm. Estimate the maximum volume flow rate (in units of gpm) that can be pumped without cavitation.

FIGURE P14–58E

Transcribed Image Text:

Reservoir N 23- 23-21 Valve Reservoir Valve 22 Pump