Example Problem: The attached diagrams show a pump performance at an impeller speed of 1,750 rpm and a fixed impeller diameter of 13 inches. Figure 1 Simple Pump Chart: Head & Power vs. Capacity 175 70 Figure 1 illustrates the pump total head, ha, along with the pump power against its capacity (flow rate). This chart is only valid for a fixed impeller rotation rate of 1,750 rpm and a fixed impeller diameter of 13 inches. Figure 2 demonstrates the pump head along with the pump efficiency against flow rate. This figure is also valid for a fixed impeller rotation rate of 1,750 rpm and a fixed impeller diameter of 13 inches. 150 60 Answer the following questions, using the pump performance curves and Affinity laws. 125 50 a. How much is the total head, the power, and the efficiency of the pump at a flow rate of 1.500 gal/min, when the impeller speed is 1,750 rpm and impeller diameter is 13"? 100 40 Answer Table for Parta Total Head, Power ha (ft) (hp) Total Head, hA (ft) Power (hp) Capacity (gal/min) 1,500 Efficiency (%) 75 Power 30 Head 50 20 b. During the operation of the pump, the impeller speed is changed to 1,250 rpm, but the same 13" impeller is used. How much flow can the pump transfer at this speed? What would be the total head on the pump? How much power would the pump need at the new speed? 1,750 rpm 13" Impeller 25 10 Answer Table for Part b Capacity Total Head, (gal/min) ha (ft) Power (hp) 0 0 0 3,000 500 1,000 1,500 2,000 2,500 Capacity (Flow Rate (US gal/min) Figure 2 Simple Pump Chart: Head & Efficiency vs. Capacity 180 90 160 80 140 70 120 60 100 50 Total Head,h (ft) Efficiency (%) 80 40 Efficiency Head 60 30 40 20 1,750 rpm 13" Impeller 20 10 0 0 0 3,000 500 1,000 1,500 2.000 2,500 Capacity (Flow Rate (US gal/min)