8.
The night vision goggle AN/PVS-7A was designed specifically to be charged and filled
with the purge device as outlined in TM 11-5855-262-24-1. This is the only authorized method
to purge the night vision goggle AN/PVS-7A. It is not recommended that the purge kit, fire
control be used to purge and fill the night vision goggle. The construction of the AN/PVS-7A
does no provide for nitrogen flow through. The night vision goggle wire body assembly is made
of plastic, and charging the goggle with nitrogen at greater than 3 PSI could result in personnel
injury or damage to the equipment.
9.
Prior to purging and filling the night vision goggle, an operational check and
troubleshooting procedure should be conducted on the purge device as outlined in TM 11-5855-
262-24-1, Annex A, page A-2.
10.
The following procedure is to be followed when purging the night vision goggle
AN/PVS-7A, and is IAW TM 11-5855-262-24-1, paragraph 2-7 purging unit (see TM extract on
page 97):
Step 1.
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 5-2.
Step 2.
Set regulator valve handle (1) for zero by rotating control (counterclockwise) until
there is no spring pressure on control.
Step 3.
Open nitrogen tank valve (5). The high pressure gauge (4) will indicate tank
pressure. If pressure is below 50 pounds, replace tank.
Step 4.
Set purge device (8) PUMP/NITROGEN switch (11) to PUMP and LEAK
TEST/PURGE (10) switch to PURGE.
Step 5.
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 feel and hear gas escaping.
Step 6.
Unscrew and remove purge cover with purge cover tool in the purge kit. Unscrew
purge screw using 2.5mm hex key. Examine seal and replace, if necessary.
(Figure 5-2.)
Step 7.
Attach purge adapter to purge port on goggle. Engage purge adapter in purge
screw and back off purge screw three complete turns.
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