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Pump Selection Procedure <br /> A. Determine pump capacity: <br /> Gravity Distribution <br /> 1. Minimum use is 600 gallons per hour(10 gpm)to stay <br /> ahead of water use rate. <br /> 2. Maximum suggested for delivery to a drop box of a home <br /> system is 2,700 gallon per hour(45 gpm)to prevent build-up <br /> of pressure in the drop box. <br /> Pressure Distribution <br /> 3. <br /> a. The number of perforated laterals is 3. <br /> b. The perforation spacing will be 3 feet on center. <br /> c. Subtract 2 ft. from the rock layer length; <br /> 63 —2 =61 feet <br /> d. Determine the number of spaces between perforations; <br /> by dividing 3.c by 3.b; <br /> 61 /3 = 20 spaces <br /> e. 20 spaces + 1 =21 perforations per lateral <br /> f. Multiply the 3.a and 3.e to determine <br /> the total number of perforations; <br /> 3 x 21 =63 total perforations <br /> g. Multiply 3.f and 0.74 to determine the gpm; <br /> 63 x 0.74 =46 alg lons per minute <br /> SELECTED PUMP MINIMUM CAPACITY = 46 GPM <br /> B. Determine the head pressure requirements. <br /> 1. Elevation difference between the pump <br /> and the point of discharge is 15 feet. <br /> 2. Add 5 feet of head for pressure required at the <br /> manifold if this is a pressure distribution system. <br /> 3. Friction loss; <br /> a. Enter the friction loss multiplier from <br /> the table wit gpm & pipe diameter. <br /> 4.76 <br /> b. Determine the pipe length from the <br /> pump to the discharge point. Add 25% <br /> to the pipe length for fitting loss. <br /> @125 x 1.25 = 156 feet <br /> c. Calculate the total friction loss by multiplying <br /> B.3a by B.3b and dividing by 100 and rounding up; <br /> (�4.76 x 156)/ 100= 8 feet <br /> 4. Calculate the total head required by totaling B.1, B.2, and B.3c; <br /> 15 + 5 + 8 =28feetofhead <br /> TOTAL REQUIRED MINIMUM HEAD IS 28 FEET. <br /> The pump installed must be able to deliver at least 46 gallons per minute with at <br /> least 28 feet of head. <br />