2. Place the regulator supply control valve
lever in the OFF position, and the diluter control
lever in the 100-percent OXYGEN position.
3. Ensure that the regulator emergency
pressure control lever is in the NORMAL
position.
4. Mount the adapter supplied with the test
stand (NAVAIR Drawing No. 1172AS136), and
connect the regulator outlet to the N2 INPUT
connection in the altitude chamber.
5. Connect a line from the LOW PRESS
connection to REFERENCE TAP in the altitude
chamber. Plug the rubber hose attached to the
piezometer by using the piezometer plug supplied
with the test stand. Ensure that the LOW
PRESSURE REGULATOR is not loaded. This
will prevent N2 supply cylinder pressure from
passing onto the INLET PRESSURE ON/OFF
valve which could damage the test item or injure
the test stand operator.
6. Turn the INLET PRESSURE ON/OFF
valve to the ON position. The vacuum vent must
be opened one to two turns when you operate the
vacuum pump. Turn the vacuum pump on.
7. Turn the PRESSURE SELECTOR valve
to the H2O position, and fully open the
LEAKAGE CONTROL valve.
8. Ensure that the LEAKAGE SELECTOR
valve is in the HIGH RANGE position.
9. The leakage rotameter is calibrated with
an applied pressure of 70 psig. The inward leakage
test requires that a suction of 9.0 in H2O be
applied to the regulator outlet and the rotameter.
This pressure difference (9.0 in H2O vice 70 psig)
creates a wide variance between actual leakage and
indicated leakage.
The maximum allowable
leakage for the inward leakage test is 200 cubic
centimeters per minute, and is displayed as 740
ccm on the high range leakage rotameter.
NOTE: Because of labeling on gauges, the
abbreviation ccm is used in this text. Since
the cubic centimeter has been replaced by
the milliliter, this abbreviation should be
ml/min instead of ccm. The proper
abbreviation may appear on later equip-
ment and newer technical manuals.
Slowly open the OUTPUT valve until 9 inches
o f H2O s u c t i o n i s i n d i c a t e d o n t he
PRESSURE/SUCTION manometer. Any leakage
will be displayed on the HIGH RANGE
LEAKAGE rotameter. The maximum allowable
indicated leakage reading is 740 ccm (actual 200
ccm). Record the indicated leakage on the
Performance Test Sheet.
10. Close the OUTPUT valve and the
LEAKAGE CONTROL valve. Turn the vacuum
pump OFF. Turn the INLET PRESSURE
ON/OFF valve to the OFF position.
Table 12-5A.—Troubleshooting (Inward Leakage Test)
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