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F-15 <br /> PUMP SELECTION PROCEDURE <br /> A. Determine pump capacity: <br /> 1. Minimum suggested is 600 gallons per hour (10 gpm) - <br /> to stay ahead of water use rate <br /> 2. Maximum suggested for deliv• •, to a drop box of a home <br /> system is 2700 gallons per hot ~ (45 gpm) to prevent <br /> buildup of pressure in drop br <br /> 3. Use value from design of pre distribution system <br /> SELECTED PUMP CAPACITY 4 gpm <br /> B. Determine head requirements: <br /> 1. Elevation difference between pump and point of discharge feet <br /> yr 2. If pumping to a pressure distribution system, add 5 feet <br /> for pressure required at manifold feet <br /> 3. Friction loss <br /> a. Enter friction loss table with gpm and pipe diameter. <br /> Read friction loss in feet per 100 feet from page F-18. <br /> F. L. = Z , i, `� ft/100 ft <br /> b. Determine total pipe length from pump to discharge <br /> point; Add 25 percent to pipe length for fitting <br /> loss, or use a fitting loss chart. Equivalent pipe <br /> length = 1.25 times pipe length = 1.25 x 3-0 _ 4),5- feet <br /> /"."\ • <br /> c. Calculate total friction loss by multiplying <br /> friction loss in ft/100 ft by equivalent pipe <br /> length. <br /> Total friction loss = x ( c _ / , 7 feet <br /> 4. Total head: required is the sum of elevation difference, <br /> special head requirements, and total friction loss. <br /> + + <br /> TOTAL HEAD / c7 feet <br /> C. Pump selection <br /> 1. A pump must be selected to deliver at least YO gpm <br /> with at least feet of total head. <br /> D. To maximize pump life select sump size for 4 to 5 pump <br /> operations per day. <br /> E. Calculate drainback <br /> 1. Determine total pipe length, feet. <br /> 2. Determine liquid volume of pipe, gallons per <br /> 100 feet. (See page E-18) <br /> 3. Multiply length by volume: Drainback quantity = <br /> feet x gallons/100 ft = gallons <br /> 4. Suggested drainback quantity is 10 percent of pumped quantity. <br /> A larger drainback percentage will decrease pump station <br /> efficiency slightly but pumping energy costs are usually a <br /> relatively small part of the total household energy costs. <br />