The discharge, head, and efficiency data of a centrifugal pump follow. The best efficiency point (bep)...

 

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The discharge, head, and efficiency data of a centrifugal pump follow. The best efficiency point (bep) is at 2500 gpm. The impeller diameter is 15 in., and the operating speed is 2500 rpm. Plot the characteristic curves of head discharge and efficiency as diagramed in Figure 11, and locate the bep and the recommended pump operating range. Calculate the power input at the bep. Discharge Head Efficiency Discharge Head Efficiency (gpm) (ft) (%) (gpm) (ft) (%) 0 105 500 100 1000 688 41 96 1500 91 1=32 2000 83 85 2500 72 88 63 3000 58 841 78 3500 42 65 Head-discharge curve Shutoff head operating efficiency Efficiency Discharge (Pumping rate FIGURE 11 Characteristic curves for a centrifugal pump operating at a constant speed. 2. Draw a head-discharge curve for the pump described in the problem above operating at 1700 rpm. Locate points along the curve at 60 percent bep, and 120 percent bep, and sketch the pump operating envelope as shown in Figure 12. (Answer bep: 1700 gpm, 33 ft) 3. Draw hydraulic gradients for the system in the figure below. The ground levels at points A, B, and C are at the same elevation. The lift pumps at A provide flow at a discharge of 400 kPa, the water level elevation in the elevated storage tank at C is 35 m, and the equivalent pipelines to the load center at point B are as given in the illustration. Use the nomograph in Figure 7. (a) Draw the hydraulic gradient and calculate the total discharge at B from the lift pumps and outflow from elevated storage when the water pressure at B equals 275 kPa. (b) Draw the hydraulic gradient and calculate the discharge into elevated storage with no discharge at the The discharge, head, and efficiency data of a centrifugal pump follow. The best efficiency point (bep) is at 2500 gpm. The impeller diameter is 15 in., and the operating speed is 2500 rpm. Plot the characteristic curves of head discharge and efficiency as diagramed in Figure 11, and locate the bep and the recommended pump operating range. Calculate the power input at the bep. Discharge Head Efficiency Discharge Head Efficiency (gpm) (ft) (%) (gpm) (ft) (%) 0 105 500 100 1000 688 41 96 1500 91 1=32 2000 83 85 2500 72 88 63 3000 58 841 78 3500 42 65 Head-discharge curve Shutoff head operating efficiency Efficiency Discharge (Pumping rate FIGURE 11 Characteristic curves for a centrifugal pump operating at a constant speed. 2. Draw a head-discharge curve for the pump described in the problem above operating at 1700 rpm. Locate points along the curve at 60 percent bep, and 120 percent bep, and sketch the pump operating envelope as shown in Figure 12. (Answer bep: 1700 gpm, 33 ft) 3. Draw hydraulic gradients for the system in the figure below. The ground levels at points A, B, and C are at the same elevation. The lift pumps at A provide flow at a discharge of 400 kPa, the water level elevation in the elevated storage tank at C is 35 m, and the equivalent pipelines to the load center at point B are as given in the illustration. Use the nomograph in Figure 7. (a) Draw the hydraulic gradient and calculate the total discharge at B from the lift pumps and outflow from elevated storage when the water pressure at B equals 275 kPa. (b) Draw the hydraulic gradient and calculate the discharge into elevated storage with no discharge at the