Irrigation Professionals with questions about ... - Hunter Industries

Line #5 - Pressure at POC: If the POC is higher in elevation(uphill) in relation to the discharge point, the pressure change (line #4) issubtracted from the pressure at the source (line #1). If the POC is lower inelevation (downhill), the change in pressure would be added to thepressure at the source.Sample Problem: 70 PSI (at the discharge point)- 7.79 PSI (POC is uphill from main)= 62.21 PSILine #6 - Delivery Line: This is the line that runs from the dischargepoint to the POC. Data on size and type are gathered when determiningpump/well capacity.Sample Problem: 65 ft. of 1 in. Schedule 40 PVCLine #7 - Isolation Valves: These are often used to isolate portionsof the system. They may be a gate valve, ball valve, or globe type valve.There are none used in this example.Line #8 - Other: This line would be for other system componentswhich could cause a pressure loss in the system such as a water filter,pressure regulator, or a backflow prevention device. There are none forthis example.B. Determine Design CapacityThe Design Capacity is the maximum flow rate at the discharge pointwhich is available for system operation. The Design Capacity is limited bythe capacity of the well and pump. Additionally, pump systems should bedesigned at no more than 90% of system capacity to reduce the chance ofpump cavitation. Pump cavitation is caused when the entrance pressure isreduced to a point where air pockets form in the pump. The result isinefficient pump operation, and the pump may prematurely wear out andfail.Line #9 - Pump/Well GPM Capacity: The pump/well GPMcapacity is determined by testing, or is obtained from the pump installationcompany, as described above. Record the pump's available flow atdischarge point (from line 2).Sample Problem: 15 GPM