(Solved): Question 2 A water supply system for a high-rise building is shown in Figure Q2. Water is pumped f ...

Question 2 A water supply system for a high-rise building is shown in Figure Q2. Water is pumped from an open tank in the basement through a 37.5-m-long and 50-mm-diameter pipeline with the friction factor f=0.02 to another open tank. The water surface of the other open tank is 25 m above that of the supply tank. In the system, two identical centrifugal pumps are operating in parallel to adjust the amount of supply water. In Table Q2 it gives the operating characteristic of a centrifugal pump. ' The minor loss coefficients of the filter, the two pumps, and the valve are 1, 0.8, and 1.2, respectively. Ignore other minor loses. Table Q2 Operation characteristics of a centrifugal pump Pump Head H (m) 90 80 70 60 50 Flow Rate Q (m/s) 0.0045 0.0061 0.0075 0.0086 0.00955 0.01075 Efficiency 0.58 0.82 0.82 0.76 0.62 30 0.75 25 m Valve k-1.2 Filter Pumps k-0.8 Figure Q2 Water supply system for a high-rise building m. (a) Determine the volume flow rate in the pipeline. (12 marks) (b) Calculate the motor power required for supplying the water flow. (3 marks) (c) The required net positive suction head (NPSHg) of the pump is 3 m. The water is at 20°C and 1.01 bar. The total length of the pump suction line is 2.5 m. Determine the maximum installation height that the pump can be located above the water surface without cavitation. The saturation water pressures at various temperatures are given in the Appendix. (10 marks) Given: Net positive suction head available (NPSHA) is defined as NPSHA = 1 + - () -( = Ps pg 29