Irrigation Professionals with questions about ... - Hunter Industries

Line #10 - Pump Safety Factor: In order to reduce the chance ofpump cavitation, the design capacity should not exceed 90% of thecontinuous supply available at the discharge point. Here, the pump/wellGPM capacity is multiplied by 10% (0.10).Sample Problem:A) Record the pump/well GPM capacity (Line #9) in the firstspace on Line #10.B) Multiply the pump/well GPM capacity by 0.10. 15 x0.10 = 1.5 GPM capacity safety factorLine #11 - Design Capacity: The Design Capacity is the maximum flowrate at the discharge point that is available for system operation. This isdetermined by subtracting line #10 from line #9.Sample Problem: 15.0 GPM - 1.5 GPM = 13.5 GPMC. Calculate Dynamic Pressure at Design CapacityNow that a flow rate (Design Capacity) has been established, this flow ratecan be used to estimate the dynamic pressure at the POC. Pressure lossesfrom the source to the POC include those through the delivery line,isolation valves, or other system components.Note: not all components listed are present in all systems.Line #12 - Pressure Reduction - 10% as Pump SafetyFactor: To further reduce the chance of pump cavitation, the dischargepressure should not exceed 90% of the pump's available pressure at thedischarge point. Here, the stated pressure is multiplied by 10% (0.10).Sample Problem:A) Record the dynamic pressure at the discharge point (line #1) inthe first space on line #12.B) Multiply the dynamic pressure at the discharge point by 0.10.Sample Problem: 70 x 0.10 = 7 PSI pressure safety factorLine #13 - Pressure Loss in the Delivery Line: Determine thepressure loss in the delivery line.Sample Problem: 1 inch Schedule 40 PVCA) Turn to the friction loss chart for the type of delivery line used,page 2 in the Hunter Friction Loss Tables at the end of thisdesign manual.B) Read down the left hand column (Flow GPM) to the designcapacity, line 11.