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NOZ-CHEK
®Cryogenic
Installation, Operation & Maintenance
NOZ-CHEK
®Cryogenic
Installation, Operation & Maintenance
6.0 FAULT FINDING AND CORRECTION
One should keep in mind the purpose of the Noz-Chek®
when operating difficulties are encountered. The valve
is supposed to check reverse flow. When the valve fails
to perform this function, the following points should be
checked:
6.1 The valve fails to check
a) Spring may be broken.
b) Corrosion may have destroyed all or part of the Disc.
This would indicate that the disc material is incorrect
for the media.
c) Debris in the line may prevent the disc from closing.
d) If the valve is fitted with a switch, the grub screw
(26) may have become loose or screwed out and
the magnet housing (25) is impeding the disc’s
(3) movement. To remedy this, clean both threads
thoroughly, apply an even coat of “Jet Lube Thick
or Thin” thread paste to the threads, and screw the
grub screw (26) back into the hole in the disc (3) and
magnet housing (25) and tighten.
6.2 The valve slams violently when flow reverses
a) The spring in the valve is broken and hence does not
perform its function.
b) The spring is too weak. Some flow conditions
require the valve to close quicker than others. Unless
the disc closes before backflow occurs, possible
slamming will result. A stronger spring will help
remedy this problem.
6.3 The valve leaks excessively across seal
a) The seal is defective.
b) Disc is not seating properly.
c) The Spring Energised seal (or Metal C-Seal) may be
damaged.
d) If the valve is fitted with a switch, the grub screw
may have become loose and the magnet housing is
impeding the disc’s movement. To remedy this, clean
both threads thoroughly, apply an even coat of “Jet
Lube Thick or Thin” thread paste to the threads, and
screw the grub screw (26) back into the hole in the disc
(3) and magnet housing (25) and tighten.
6.4 The valve leaks between the flange faces
a) The serrations on either the Noz-Chek II ® flange or
the companion flange are damaged.
b) A new gasket or seal ring is needed.
6.5 There is no flow through the line
a) The valve is installed backwards.
b) The valve is new and the disc has not been broken
loose from the valve seat.
6.6 The switch is not working (if fitted)
a) Ensure switch is connected to relevant system
properly, check the cable for wear or damage and
replace if necessary. Also check that the system has
power.
b) The magnet housing may have become loose and is
impeding the disc’s movement. To remedy this, clean
both threads thoroughly, apply an even coat of “Jet
Lube Thick or Thin” thread paste to the threads, and
screw the grub screw (26) back into the hole in the disc
(3) and magnet housing (25) and tighten.
c) Check for deposits on the sensing surfaces of the
magnet housing and switch housing that could effect
the operation of the switch and clean if necessary.