8.
The TM 11-5855-238-24&P, Chapter 5; paragraph 5-9/10 (TM extract on page 91 gives
the prescribed procedure for the purging of the NVGs AN/PVS-5/A. This procedure calls for the
purging kit, fire control; however, the purge device can also be employed to purge the NVGs.
The basic procedure as stated in the TM must be modified in the following manner: (See Figure
2-2.)
NOTE:
This procedure applies only to the AN/PAS-5&5A which use image intensifiers MX-
9648/UV and MX-9916/UV. Procedures remain the same for subparagraph a.,
Removal of Assemblies. Variation will start in subparagraph b.5 of paragraph 5-9
and subparagraph b.2 of paragraph 5-10.
Step 1.
Insert eyepiece lens assembly fully into image intensifier and tighten eyepiece
adapter retainer with spanner wrench.
Step 2.
Rotate eyepiece lens assembly to midpoint of its travel.
Step 3.
Ensure that valves are closed on the fire control purging tool and nitrogen tank
before connecting equipment. Connect purge kit, fire control to nitrogen tank and
purge device as shown in Figure 2-2.
Step 4.
Set regulator valve handle (1) for zero by rotating control (counterclockwise) until
there is no spring pressure on control.
Step 5.
Open nitrogen tank valve (5). The high pressure gauge (4) will indicate tank
pressure. If pressure is below 50 pounds, replace tank.
Step 6.
Set purge device (8) PUMP/NITROGEN switch (11) to PUMP and LEAK
TEST/PURGE (10) switch to PURGE.
Step 7.
Slowly adjust regulator handle (1) by turning it clockwise until low pressure
gauge (3) indicates 3 1 PSI. Purge device gauge (9) should indicate 0 1 PSI
and you should hear gas escaping.
Step 8.
Connect purge adapter (Figure 2-3) to purge valve (Figure 2-3) located on top of
mounting collar.
Step 9.
Using large knob of purge adapter, engage tabs into slots of purge valve (Figure
2-3). Rotate counter-clockwise to loosen purge valve 2 full turns.
Step 10.
Purge monocular by pumping vacuum handle (12) until purge device gauge (9)
indicates greater than 20 inches of Hg.
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