Step 17.
Purge eyepiece housing assembly by pumping vacuum handle until purge device
gauge indicates greater than 20 inches Hg.
Step 18.
Position purge device LEAK TEST/PURGE switch (10) to LEAK TEST and
observe that the purge device gauge (9) indicates a steady vacuum of 20 inches of
Hg or higher. If unable to observe a steady vacuum reading, a leak is present.
Stop purge procedure and seal night vision device leak(s). If purge device gauge
(9) indicates a steady vacuum, position purge device LEAK TEST/PURGE switch
(10) to PURGE.
Step 19.
Set purge device PUMP/NITROGEN switch to NITROGEN and observe that the
purge device gauge indicates 3 + 1 PSI.
Step 20.
Position purge device LEAK TEST/PURGE switch (10) to LEAK TEST and
observe that the purge device gauge (9) indicates a steady reading of 3 1 PSI. If
unable to observe a steady reading, a leak is present. Stop purge procedure and
seal night vision device leak(s). If purge device gauge (9) indicates a steady
pressure reading, position purge device LEAK TEST/PURGE switch (10) to
PURGE.
Step 21.
Repeat steps 17 through 20 three additional times.
Step 22.
Press in large knob on the purging wrench and adapter assembly until it engages
gas inlet valve on eyepiece housing assembly, and then rotate it clockwise until
valve is closed.
Step 23.
Set purge device PUMP/NITROGEN switch to PUMP, and LEAK TEST/PURGE
switch to PURGE.
Step 24.
Unscrew purging wrench and adapter assembly from driver's night vision viewer
eyepiece housing assembly gas inlet valve.
Step 25.
Prepare for continued purge/fill procedure or remove purging wrench and adapter
assembly, turn off nitrogen tank valve, and remove and store fire control tool set,
and purge device.
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