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REGULATED LOW-PRESSURE NITROGEN SYSTEM | Up
Aircrew Survival Equipmentman 1 & C - Aviation theories and other practices | Next
DIFFERENTIAL PRESSURE INDICATING SYSTEM |
Turn the leakage selector valve to LOW
RANGE. No leakage should be indicated on the
low-range rotameter. Return the leakage-selector
valve to HIGH RANGE and the inlet pressure
on/off valve to the ON position.
Slowly open the low-pressure regulator until
the regulated low-pressure gage indicates 160 psig.
(The N2 input pressure gage should read its gage
guard pressure of 145 ± 5 psig). Turn the inlet
pressure on/off valve to OFF. No leakage should
be indicated on the high-range leakage rotameter.
Turn the leakage selector valve to the LOW-
RANGE position. No leakage should be indicated
on the low-range leakage rotameter. Use the
system bleed valve to decrease the pressure to 70
psig. You must turn the low-pressure regulator
counterclockwise until 70 psig is maintained.
Leave the test stand in this condition; it is set up
for you to perform your next leakage test.
ROTAMETER SYSTEM
The purpose of the rotameter system is to
determine leakage or to make adjustments to
items that require bleed adjustments, such as the
20004 miniature regulator. The system consists of
two in-system rotameters and one overload
rotameter as shown in figure 2-6. The source of
pressure for the in-system rotameters is the
low-pressure regulator (N). You receive your
source of pressure for the overboard rotameter
from the item under test.
PRESSURIZING THE
ROTAMETER SYSTEMS
To use the rotameter system, turn the inlet
pressure on/off valve (L) to ON.
NOTE: Before you pressurize the rotameter
systems, be sure the leakage selector valve (F) is
in the HIGH position. This valve should always
be in the HIGH position unless you are using the
low-range rotameter to read low readings.
Turn the leakage on/off valve (G) to ON and
the inlet pressure on/off valve to OFF. Look at
your high-range leakage rotameter. If no leakage
is indicated, turn your leakage selector valve (F)
to the LOW RANGE position. Check your
low-range leakage rotameter for leaks. In both
leakage tests if the small ball rises in the
Figure 2-6.—Model 1172AS100 rotameter system.
2-7
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