Nelson Irrigation Corp. 848 Airport Rd. Walla Walla, WA 99362-2271 USA Tel: 509.525.7660 Fax: 509.525.7907 E-mail: [email protected] Web site: www.nelsonirrigation.com
Control Valve
Application
Guide
2.4.2 DESCRIPTION OF FUNCTIONS LISTED IN THE SELECTION GUIDE
MANUAL ON-OFF
VALVE CONTROL FUNCTION
(items D1, E1 on the VALVE SELECTION GUIDE):
The
MANUAL ON-OFF
model of the 800 Series Control Valve is a hydraulically operated sleeve type valve with a manual
control. The
MANUAL ON-OFF
control is used to open or close the valve. The valve is normally either in the fully opened
or the closed (shut off) position but pointing the selector handle mid- way between ports can hold the sleeve in a partly open
position. The "AUTO" position on the selector has no effect on valve control but is used when the valve is equipped with
automatic controls.
ELECTRIC ON-OFF
VALVE CONTROL FUNCTION
(items D1, E20 through E72 on the VALVE SELECTION GUIDE):
The
ELECTRIC ON-OFF
model of the 800 Series Control Valve is a hydraulically operated sleeve type valve with an electric
solenoid control. The valve is either in the fully opened or the closed (shut off) position. When the selector is pointed to the
"AUTO" position then the electric solenoid is used to automatically open or close the valve. The 3-way electric solenoid must
be energized to open the valve and de-energized to close the valve. Pointing the manual selector handle to "OPEN" or
"CLOSE" will override the "AUTO" control except when the selector is pointed to "OPEN" the pressure reducing control still
functions but the solenoid has no effect.
PRESSURE REDUCING MANUAL ON-OFF
VALVE CONTROL FUNCTION
(items D2 through D4, E1 on the VALVE SELECTION GUIDE):
The
PRESSURE REDUCING MANUAL ON-OFF
model of the 800 Series Control Valve is a hydraulically operated sleeve
type valve with a pressure reducing pressure control kit and a manual on-off. When the selector is pointed to the "AUTO"
position then the valve will automatically reduce a higher inlet pressure to a constant lower downstream pressure. The
pressure reducing control is adjustable to give a constant down stream pressure even with fluctuating upstream pressure.
The manual selector is used to manually open or close the valve. Pointing the manual selector handle to "OPEN" or "CLOSE"
will override the "AUTO" control except, when the selector is pointed to "OPEN" ,a safety plug installed at the factory must
first be removed to open the valve.
PRESSURE REDUCING ELECTRIC ON-OFF
VALVE CONTROL FUNCTION
(items D2 through D4, E20 through E72, on the VALVE SELECTION GUIDE):
The
PRESSURE REDUCING ELECTRIC ON-OFF
model of the 800 Series Control Valve is a hydraulically operated sleeve
type valve with a pressure reducing pressure control kit and an electric solenoid. When the selector is pointed to the "AUTO"
position then the valve will automatically reduce a higher inlet pressure to a constant lower downstream pressure. The
pressure reducing control is adjustable to give a constant downstream pressure even with fluctuating upstream pressure. The
electric solenoid is used to automatically open or close the valve remotely. When in the "AUTO" position the 3-way electric
solenoid must be energized for the pressure control to work and de-energized to close the valve. Pointing the manual selector
handle to "OPEN" or "CLOSE" will override the "AUTO" control except, when the selector is pointed to "OPEN" , the pressure
reducing control still functions but the solenoid has no effect.
PRESSURE SUSTAINING/RELIEF
VALVE CONTROL FUNCTION (items D5,D8,D9, with E1 on the VALVE SELECTION GUIDE):
The
PRESSURE SUSTAINING/RELIEF
model of the 800 Series Control Valve is a hydraulically operated sleeve type valve
with a pressure sustaining/relief pressure control kit and a manual on-off. When the selector is pointed to the "AUTO" position,
then the pressure control kit will automatically sustain the upstream pressure on the valve. If the valve is
installed in-line of
the main flow
,it will maintain the desired upstream pressure by controlling the amount of water that is allowed to flow through
the valve. If the valve is
installed on a tee or bypass which allows free discharge
, then it will maintain the desired upstream
pressure by relieving flow through the discharge tee. The pressure sustaining/relief control is adjustable to sustain or relieve
at a desired upstream pressure. The manual selector is used to manually open or close the valve. Pointing the manual selector
handle to "OPEN" or "CLOSE" will override the "
AUTO
" control, a safety plug installed at the factory must first be removed to
open the valve. Several variations of this control are available to accomplish the desired result. See Appendix D for a quick
lookup table of options.
RATE-OF-FLOW CONTROL
Valve Control Function (items D18 on the VALVE SELECTION GUIDE):
The
RATE-OF-FLOW CONTROL
model of the 800 Series Control Valve is an add on control that maintains a preset flow
rate by means of a velocity sensing probe in the pipe. An adjustment screw is used to set the desired flow rate. This control
can be combined with most other controls.
SELECTING THE RIGHT VALVE
6
