70. Benzene at atmospheric pressure and 41C is in a tank with a fluid level of 15ft above a pump. The pump provides a pressure increase of 50 psi to a destination 25ft above the tank fluid level. The suction line to the pump has a length of 20ft and is 2-in, schedule-40. The discharge line has a length of 40ft to the destination and is 1.5-in schedule- 40 . The flowrate of benzene is 9.9lb/sec. a. Derive an expression for the NPSH in head units ( ft of liquid) vs. flowrate in ft3/s. b. Derive an expression for the system curve in head units (ft of liquid) vs. flowrate in ft3/s. Www.ebook3000.com 73 c. Locate the operating point on both plots on Figure P1.70. d. What is the maximum flowrate before cavitation becomes a problem? e. What is the pressure drop across the valve at the operating point? f. What is the maximum flowrate possible with one pump, two pumps in series, and two pumps in parallel? log10Pbenzene(mmHg)=6.90565T(C)+220.791211.033benzene=51.9lb/ft3benzene=0.85cP Figure P1.69