Nelson Irrigation Corp. 848 Airport Rd. Walla Walla, WA 99362-2271 USA Tel: 509.525.7660 Fax: 509.525.7907 E-mail: info@nelsonirrigation.com Web site: www.nelsonirrigation.com
800 SERIES CONTROL VALVE — PRESSURE REDUCING MANUAL ON-OFF CONTROL
TROUBLE SHOOTING GUIDE
SYMPTOM: Valve will not close when the manual selector valve is in the “CLOSE” position.
CHECK ITEMS: bCheck for leaks on all tube lines and fittings. If it is
necessary to remove any control tube lines from the fittings
then use an opposing force as shown here. Pull the tube
while pressing in the opposite direction on the fitting ring.
bCheck that water can flow through the tube "U" which
connects the upstream (high pressure) side of the main
valve to the “
CLOSE” port of the manual selector valve. Refer
to the control function diagram. If little or no flow, find the
reason for the blockage and clear it.
bCheck the filter to assure it can pass adequate water flow. This can be deceptive
because when you unhook the line from the filter some water can still flow. A partially
blocked filter will reduce the valve closing response time. If little or no flow is present then
clean the filter. If the valve is equipped with an external filter open the valve on the filter
to clean the filter.
bCheck the sleeve for damage. To do this, point the
manual selector valve to the “
OPEN” position. The total
volume of water that should flow from the sleeve
chamber through the “OPEN” port is the same as the
volume required to fully open or close the valve. If more
than this volume of water continues to flow, then the
sleeve has been punctured and must be replaced.
SYMPTOM: Valve will not open or has excessive pressure drop when the manual selector valve is in
the “OPEN” position.
CHECK ITEMS: bCheck all tube lines and fittings for blockages and kinks. If there are no obstructions
then check that upstream pressure is adequate. The 200 psi rated valve starts to open at
8 psi and is fully open at 30 psi. The 80 psi rated valve starts to open at 10 psi and is fully open
at 18 psi.
The 50 psi rated valve starts to open at 8 psi and is fully open at 10 psi.
bCheck the total volume of water in the sleeve chamber to verify that enough water volume
(see table) flows between fully open and fully closed. This water volume can be measured
as it flows from the “OPEN” port. If there is still a large pressure drop across the valve then
debris could be caught blocking the flow on the upstream side of the cage. This type of
obstruction will require removing the valve from the line and cleaning out the debris.
CAUTION! BE CAREFUL TO SHUT DOWN PRESSURE ON THE SYSTEM BEFORE SERVICING THIS
VALVE! IF THE VALVE IS CLOSED AND UNDER PRESSURE, DISCONNECTING THE CONTROL
TUBE "U" (8970-005) WILL CAUSE RAPID OPENING OF THE VALVE! SYSTEM DAMAGE COULD OCCUR!
!!
!!
!
WATER VOLUME REQUIRED TO
FULLY OPEN OR CLOSE VALVE
8" 4 Quarts
6" 2 Quarts
4" 1 Pint
3" 1 Cup
2" 5 oz (145ml)
3/02
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