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
3/05
800 SERIES CONTROL VALVE — PRESSURE SUSTAINING/RELIEF & RATE-OF-FLOW CONTROL
TROUBLE SHOOTING GUIDE
SYMPTOM: 800 Series valve will not pressure sustain/relief.
CHECK ITEMS: bCheck all tube lines and fittings are connected as shown on the diagram and that all
isolation valves are in the open position.
bCheck that the # 9358 spool valve inside the 9529 pressure control is not stuck. This
spool valve must be free to move in response to upstream pressure. Inspect the spool valve
by unscrewing the sensitivity bushing assembly as shown in this drawing.
bCheck the filter to assure it can pass adequate water flow. A partially blocked filter will
reduce the valve sustaining/relief and closing response time. If little or no flow is present
then clean the filter.
SYMPTOM: The sustaining pressure is unstable (fluctuating high and then low several times a minute)
and water is discharged from the exhaust port during each low pressure cycle.
CHECK ITEMS: bCheck for trapped air in the pipe system upstream from the 800 Series valve. This
problem is not easily detected. The installation of a Nelson ACV200 automatic air release
valve will help rid the system of trapped air. It is recomended this type of air release valve
be installed at high elevation points on the system where air could accumulate. Typical
location for the accumulated air is shown.
bChange the
BLUE sensitivity bushing to RED or BLACK in order to change the valve response
to the pressure swing cycle.
NoteNote
NoteNote
Note: Be sure to drain the system to reduce the potential of winter freeze damage.
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