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• 5 e.e <br /> • <br /> F-15 <br /> PUMP SELECTION PROCEDURE <br /> A. Determine• pump capacity: <br /> J . Minimum suggested 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 yy , y • <br /> gpm <br /> B. Determine head requirements: <br /> 1 . Elevation difference between pump and point of discharge y '_'� feet <br /> 2. If pumping to a pressure distribution system, add 5 feet <br /> for pressure required at manifold <br /> 5 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. _. 2. 64/ 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 SO = 4%Z. S *feet <br /> c. Calculate total friction loss by multiplying <br /> friction loss in ft/:L00 It by equivalent pine <br /> length . Z . cv <br /> Total friction loss = D x (2. S = /, (5 feet <br /> 4. Total head required is the sum of elevation difference, <br /> special head• requirements, and total friction loss. • <br /> + s + /. (S <br /> TOTAL HEAD 110 6-5 -feet <br /> • <br /> C. Pump selection <br /> • <br /> 1 . A pump must be selected to deliver at least SAO, 3 gpm <br /> with at least /0, 65 feet of total head. <br /> D. To maximize pump life select sump size for 4 to 5 pump , <br /> operations per day. <br /> • <br /> F. Calculate drainback • <br /> 1 . Determine total pipe length, So feet .- <br /> 2. Determine liquid volume of pipe, /7, '/j gallons per <br /> 100 feet. (See 'page E-18) <br /> 3. Multiply length by volume: Drainback quantity = • <br /> 5d feet x /7.'f3, gallons/100- ft = 7. 7 gallons <br /> 4. Suggested drainback quantity is 10 percent ofpumped 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 />