the port. Connect the connection valve to the other end of the purge valve
adapter.
The purge valve adapter regulates 5 psig nitrogen into the LD/R
housing. When the housing is full and nitrogen escapes from the purge valve
adapter relief valve, secure at the main valve. You then vent the housing
by removing the low pressure exhaust port screw. Allow the housing to vent
for five seconds and replace the screw. Repeat the process ten times. When
completed, allow the LD/R to thermally stabilize for one hour at room
temperature.
Then, vent the LD/R housing by removing the low pressure
exhaust port screw. When the housing has vented, reinstall the low pressure
exhaust port screw and torque to 20-25 inch-pounds.
To check the LD/R housing for leaks, set up the equipment as for the low
pressure purge. Apply leak detection compound to the seam of the housing,
around any recently replaced controls and indicators, and the lens aperture
and eyepiece.
NOTE:
A leak is defined as a continuous stream of bubbles emitted any time
within a period of at least 15 minutes.
Use a brush to release
bubbles caused by air trapped within cracks and crevices.
Introduce the 5 psig nitrogen into the low pressure cavity of the LD/R as in
the purge procedure.
Observe the areas covered with leak detection
compound. If you detect a leak, secure the procedure and repair or replace
seals and parts as necessary. Repeat the leak check and purge procedures.
(2) The LD/R depressurization, high pressure purge and fill uses 650
20 psig nitrogen to purge and fill the internal high pressure cavity.
Figure 1-14 illustrates the equipment setup for the LD/R depressurization,
high pressure purge and fill.
NOTE:
The G/VLLD should be purged every 180 days.
Record the data of
purge and fill on DA form 2409.
To depressurize the LD/R internal cavity, you must remove the LD/R valve
access cover, valve access end cap, and fill valve extension cap.
CAUTION
The LD/R will be damaged if the fill valve extension
is over tightened.
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OD1722
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