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 6-2.
Set regulator valve handle (1) for zero by rotating control (counterclockwise) until
there is no spring pressure on control.
Open nitrogen tank valve (5). The high pressure gauge (4) will indicate tank
pressure. If pressure is below 50 pounds, replace tank.
Set purge device (8) PUMP/NITROGEN switch (11) to PUMP and LEAK
TEST/PURGE (10) switch to PURGE.
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.
Remove purge seal screw and 0-ring from rear cover assembly.
Thread purge adapter approximately three turns into goggles rear cover assembly
in place of fill screw.
Purge night vision goggle by pumping vacuum handle until purge device gauge
indicates greater than 20 inches of Hg.
Position purge device LEAK TEST/PURGE switch (10) to LEAK TEST and
observe that the purge device gauge (9) indicates a steady vacuum reading of 20
inches or greater. If unable to observe a steady vacuum reading of 20 inches of
Hg or greater, a leak is present. Stop purge procedure and seal night vision
goggle leak(s). If purge device gauge (9) indicates a steady vacuum reading,
position purge device LEAK TEST/PURGE switch (10) to PURGE.
Position purge device PUMP/NITROGEN switch to NITROGEN and observe
that the purge device gauge indicates 3 1 PSI.