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
FILTER SELECTION FOR THE 800 SERIES VALVE
The purpose of the filter on the valve control package is to protect the electric solenoid valve or pressure control regulator
from debris which could clog the small flow passages. Debris stuck in the small ports of the valve or blockage of the flow
in the control package could result in failure of the valve to function. Generally, the source of water for the control package
is the upstream side of the pipe line in which the valve is installed. There are two styles of filters to select from, the INTERNAL
and the EXTERNAL filter. One or both of these filters can be selected on any control function package. Combining the use
of both the internal and external filters is possible to achieve additional filtration protection where excessive debris or solids
are present in the water. A discussion of the operation of each filter style is shown here.
EXTERNAL FILTER (option H2)
FEATURES: The external style filter is equipped with
a 100 mesh screen which gives much greater filter
screen surface area than the internal filter. This
could mean less frequent cleaning required. The
screen can be cleaned by opening the flush valve
on the end of the filter. An isolation valve is provided
so there is no need to relieve pressure on the pipe
line or drain the system to remove and thoroughly
clean the screen.
LOW TEMPERATURE CAUTION!
The flush valve needs to be open so the external
filter can drain for winter storage or if the system
water is shut off in freezing temperatures. The
internal freeze core is designed to reduce the
danger of solid ice breaking the brass housing.
Drainage is the best procedure to avoid damage. If
the valve is to be used during low temperature frost
control then the controls need to be covered. The
result of ice forming in the control tube is that the
valve can not operate correctly.
INTERNAL FILTER (option H3)
FEATURES: The internal filter is designed to self
clean. The 100 mesh screen protrudes into the
main flow of water. The flow-by of water in the
pipe may wash off debris from the screen. If the
water is fairly clean, the internal screen may never
need cleaning.
NOTE: The pipe pressure must be shut off to
remove and thoroughly clean the screen.
The internal filter (option H3) is shipped as standard.
APPENDIX B
18
