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MAW OW OrAl <br />• � �FORoeaS F-15 <br />oeLECTION PROCEDURE <br />A. Determine pump capacity: <br />1. Minimum suggcsted is 600 gallons per hour (10 gpm) - <br />to stay ahead of water use rate <br />2. Maximum suggested for delivery to a drop box of a home <br />system is.2700 gallons per hour (45 gpm) to prevent <br />buildup of pressure in drop box <br />3. Use value from design of pressure distribution system <br />SELECTED PUMP CAPACITY . . . . . . . . . . . . . . . . <br />yy, y gpm <br />B. Determine head requirements: <br />1. Elevation difference between pump and point of discharge <br />:! �= feet <br />2. If pumping to a pressure distribution system, add 5 feet <br />for pressure required at manifold . . . . . . . . . . <br />-S 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. - Y. 2 8 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 62 - <br />77. feet <br />c. Calculate total friction loss by multiplying <br />_ , <br />°riction loss in ft/100 ft by equivalent pine <br />length. <br />` 'total friction loss x 77, ✓ a <br />?. �feet <br />4. Total head required is the sum of elevation difference, <br />special head requirements, and total friction loss. <br />J -+ S - 5 - <br />TOTAL HEAD . . . . . . . . . . . . . . . . . . . . . . <br />S feet <br />C. Pump selection <br />1. A pump must be selected to deliver at least ��/.�/ 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 />I:. Calculate drainback <br />I. Determine total pipe length, 0,2 _ feet. <br />2. Determine -liquid volume of pipe, /T. y� _ gallons per <br />100 feet. (See page E-18) <br />3. Multiply length by volume: Drainback quantity = <br />6 2 _ feet x /7•'/.3 gallons/100 it - /D. gallons <br />4. Suggested drainback quantity is 10 percent of pumped quantity. <br />A larger drainback percentage will decrease pump statiun <br />efficiency -slightly but pumping energy costs are usually a <br />relatively small part of the total household energy costs. <br />