Irrigation Professionals with questions about ... - Hunter Industries

Calculate the friction losses in the main line:Continuing toward the POC, use the total GPM for the zone, and calculate the frictionlosses in the main line. Don’t forget, you may have changed the type of pipe for themain line, so use the appropriate friction loss chart.Sample Problem:300 ft. 1-1/2 in. Class 315 PVC(Hunter Friction Loss Charts, page 3)Step 130 GPMStep 2Step 3Step 4Step 5Step 61-1/2 in.2.23 PSI loss2.23100= 0.0223 psi loss per ft.0.0223 PSI loss x 300 ft. = 6.696.69 PSI loss in the Main Line pipe between the Valve and POCCalculate the friction losses in the fittings:The friction losses for couplings, elbows, and tees can be high. Use thechart on page 10, in the Hunter Friction Loss Tables to figure the losses.An acceptable pressure loss figure to use if you don’t want to calculateeach fitting is 10% of the losses established for the pipe. It isrecommended that you calculate several systems first to see if a 10%figure is accurate to your designs.Sample Problem:Losses between Sprinkler A and B:0.84 PSILosses between Sprinkler B and C:0.92 PSILosses between Sprinkler C and D:0.62 PSILosses between Sprinkler D and E:1.06 PSILosses between Sprinkler E and the Valve: 0.83 PSILosses on the Main Line due to this zone: 6.69 PSITotal losses through pipe due to this zone: 10.96 PSI