2. Two centrifugal pumps, designated as Pump A and Pump B with Q-H characteristics given in the Fig are available at a construction site. It is required to deliver 45 lit/sec of water to a large over head tank whose water level is at elevation 10 m above the ground via a 150 mm diameter pipe, 200 m long with a friction factor of f=0.02. The operating speed of the pump impeller is 960 RPM. (a) Explain why it is necessary to operate the pumps in parallel. (b) When the pumps are operated in parallel, what are their respective operating discharges? (c) In the event when Pump B breaks down, it becomes necessary to make use of Pump A. To achieve the desired flow, it is proposed to increase the rotational speed of the impeller of Pump A. Explain how you would determine the new operating speed of Pump A if it is to be used along to deliver the desired flow? Hint: Use the affinity equations ay = ia and 10 = hpa [AY1997/98 CE3131] [QA=14 lit/s, QB=31 lit/s, 1215 RPM] 25 B 20 15! 10 5 10 20 50 40 Dischaxge Lit/sec 2. Two centrifugal pumps, designated as Pump A and Pump B with Q-H characteristics given in the Fig are available at a construction site. It is required to deliver 45 lit/sec of water to a large over head tank whose water level is at elevation 10 m above the ground via a 150 mm diameter pipe, 200 m long with a friction factor of f=0.02. The operating speed of the pump impeller is 960 RPM. (a) Explain why it is necessary to operate the pumps in parallel. (b) When the pumps are operated in parallel, what are their respective operating discharges? (c) In the event when Pump B breaks down, it becomes necessary to make use of Pump A. To achieve the desired flow, it is proposed to increase the rotational speed of the impeller of Pump A. Explain how you would determine the new operating speed of Pump A if it is to be used along to deliver the desired flow? Hint: Use the affinity equations ay = ia and 10 = hpa [AY1997/98 CE3131] [QA=14 lit/s, QB=31 lit/s, 1215 RPM] 25 B 20 15! 10 5 10 20 50 40 Dischaxge Lit/sec