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Unlevel Pressure Distribution System Design <br /> 1. Lay out system in order of highest to lowest elevation <br /> Line 1 Elevation 967.7 ft Length 31 ft <br /> Line 2 Elevation 965.1 ft Length 31 ft <br /> Line 3 Elevation ft Length ft <br /> Line 4 Elevation ft Length ft <br /> Line 5 Elevation ft Length ft <br /> 2. Change in Elevation over the Trenches <br /> Highest elevation-lowest elevation: 967.7 - 965.1 = 2.6 feet <br /> 3. Total Head= head at orifices(2ft)+ change in elevation(2) 2 ft + 2.6 ft = 4.6 feet <br /> (if greater than 5 feet modify design) <br /> 4. Calculate pressure head for each system <br /> 1. Highest Trench Elevation the Head =2 feet <br /> 2. Po+ (El - Ex) =AEx <br /> Line 1 Elevation 967.7 2+ [El -El]=2 + [ 967.7 - 967.7 ] = 2.0 feet <br /> Line 2 Elevation 965.1 2+ [El -E2] =2 + [ 967.7 - 965.1 ] = 4.6 feet <br /> Line 3 Elevation 0.0 2+ [El - E3]=2 + [ 967.7 - 0.0 ] = 0.0 feet <br /> Line 4 Elevation 0.0 2+ [El - E4]=2+ [ 967.7 - 0.0 ] = 0.0 feet <br /> Line 5 Elevation 0.0 2+ [El - E5]= 2+ [ 967.7 - 0.0 ] = 0.0 feet <br /> 5. Determine flow rate per hole(See figure E-6) <br /> Line 1 Pres 2.0 Perf Diameter 1/4 = 1.04 gpm <br /> Line 2 Pres 4.6 Pen` Diameter 1/4 = 1.55 gpm <br /> Line 3 Pres 0.0 Perf Diameter = gpm <br /> Line 4 Pres 0.0 Perf Diameter _ = gpm <br /> Line 5 Pres 0.0 Perf Diameter = gpm <br /> 6. Calculate flow for Line 1 <br /> Number of perforations= [(len•th of pipe-2)/spacing] +1 <br /> [( 31 ft-2ft) / 3 ft]+1 = 10 perforations (Check figure E-4 to make sure it is ok) <br /> Flow= number of perforations x flow rate <br /> 10 perf x 1.04 gpm = 10.4 gpm <br /> 7. Calculate the gallons per foot for Line 1 <br /> Gallons/length = 10.4 gpm / 31 ft= 0.34 gpm/ft <br /> E-6 Perforation Discharge in GPM E-4 Maximum Number of 1/4 inch perforations <br /> Pressure per lateral to guarantee<10%discharge variation <br /> Head Perforation Diameter in inches Perforation <br /> feet 1/8 3/16 7/32 1/4 Spacing <br /> 1 0.18 0.42 0.56 0.74 feet 1 inch 1.25 inch 1.5 inch 2.0 inch <br /> 1.5 0.22 0.51 0.68 0.90 2.5 8 14 18 28 <br /> 2 0.26 0.59 0.80 1.04 3.0 8 13 17 26 <br /> 2.5 0.29 0.65 0.88 1.17 3.3 7 12 16 25 <br /> 3 0.32 0.72 0.98 1.28 4.0 7 11 15 23 <br /> 4 0.37 0.83 1.13 1.47 5.0 6 10 14 22 <br /> Page 1 of 2 <br />