Adjusting the "Control Valve"
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The Control Valve is the valve that directs the flow of nitrogen from
CHAMBER/OFF/EXHAUST.
This valve may require periodic adjustment. If a leak is in the
control
valve, the symptoms are generally a continual flow of gas into the
chamber
even while the instrument is in the "off" position. The best
method
to correct this is as follows:
You will need only one tool for this- a Valve Adjustment Tool.
This
tool was provided with your instrument when you originally purchased
it.
If you have misplaced it you can purchase
another one from PMS Instrument.
1. Connect instrument to a supply tank. Remove lid of
chamber
and turn valve to the "OFF" position or "EXHAUST" position.
Listen
for gas leak. (Make sure that you are in a quiet environment
that allows you to detect when the gas hiss stops).
2. Use the allen key end of the valve adjustment tool to loosen the set
screw
in black handle of the control valve. Lift the handle straight up
to remove.
3. Using the two prong end of the valve adjustment tool, insert prongs
into packing gland over valve stem.
4. Rotate wrench clockwise until the gas leak can no longer be heard.
Caution: Do not over tighten the valve
packing, as permanent damage will result. Remove wrench, install
the black handle so that it points to the "off" position, and tighten
the
set screw in the handle. Over tightening can additionally make
the valve too tight to function normally.
Note: If the instrument is used over a wide range of temperatures,
some
adjustment may be needed due to thermal expansion within the valve;
this
is normal.
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