Irrigation Professionals with questions about ... - Hunter Industries

SAMPLE PROBLEM(PUMP SYSTEMS)Design Capacity and Working Pressure WorksheetCALCULATING DESIGN CAPACITY AND DYNAMIC PRESSUREA. Record Site Information1 Dynamic pressure at the discharge point 70 PSI2 Pump available flow at discharge point 15 GPM3 Net elevation change (discharge to POC) ± + 18 FEET (+uphill, - downhill)4 Pressure change due to elevation: Line 3 x 0.433 = - 7.79 PSI5 Pressure at POC: Line 1 +/- Line 4 = 62.21 PSINumber/Length Size Type6 Delivery Line 65 ft. 1 in. Sch 40 PVC7 Isolation Valves -- -- --8 Other -- -- --B. Determine Design Capacity GPM WithFactor Restriction Restriction9 Pump/Well GPM capacity Continuous supply available atdischarge point (Line 2) 15.0 GPM10 Pump Safety Factor Not to exceed 90% of continuous supplyavailable at discharge point 15.0 x 0.10= 1.5 GPM11 Design Capacity (subtract Line 10 from Line 9) 13.5 GPMC. Calculate Dynamic Pressure at Design CapacityPressure Losses from Discharge Point to the POC12 Pressure reduction 10% as Pump Safety Factor 70 x 0.10 = 7.0 PSI13 Pressure loss in the Delivery Line 4.19 PSI loss (per 100' ) 65 ft./100 = 2.72 PSI14 Pressure loss in the Isolation Valves: Equivalence factorxPSI loss per 100' ofstandard steel/100x Number of valves = -- PSI15 Other pressure losses_____________________________ = -- . PSI16 Pressure loss from the discharge point to POC (add Lines 12 through 15) 9.72 PSI17 Approximate Dynamic Pressure at Design CapacityDynamic pressure at the POC (Line 5 above) 62.21 PSISubtract the PSI lost from the discharge point to the POC (Line 16) 9.72 PSIApproximate Dynamic Pressure at Design Capacity 52.99 PSI