OXYGEN RATIO TEST. This test deter-
mines the amount of oxygen mixed with ambient
air up to 32,000 feet where 100-percent oxygen
will be automatically delivered to the user. To
perform the oxygen ratio rest, proceed as follows:
1. Ensure that the regulator supply valve
control lever is in the ON position, and the diluter
control lever is in the NORMAL OXYGEN
2. By using the LOW PRESSURE REGULA-
TOR, apply 150 psig to the regulator inlet. Slowly
open the VACUUM CONTROL valve (B1) and
observe the PRESSURE/SUCTION manometer.
If a rapid increase in pressure is indicated, close
down on VACUUM CONTROL valve (B1) until
pressure stabilizes. This rapid increase of pressure
shown on PRESSURE/SUCTION manometer is
caused by too fast a rate of climb in the altitude
chamber. Maintain 3.0 inches of H2O on the
OUTPUT manometer with OUTPUT valve while
ascending to altitude.
3. Using VACUUM CONTROL valve (B1),
ascend to the first test altitude shown on the
Performance Test Sheet.
4. Set the output flows specified in the
Performance Test Sheet with OUTPUT valve, and
stabilize altitude with INPUT valve.
5. Read all readings on the INPUT manome-
ter, and record all readings on the Performance
6. Continue the test for each specified altitude
and output flow shown on the Performance Test
7. Close OUTPUT valve and INPUT valve.
Descend to 27,000 feet using CHAMBER BLEED
8. If oxygen ratio test was satisfactory,
proceed to make the safety pressure and pressure
breathing test. If indicated input flows are not
within limits, an aneroid closure test must be
performed. The aneroid closure test is performed
only if regulator fails the oxygen ratio test.
ANEROID CLOSURE TEST. The aneroid
closure test is preformed only if the regulator fails
the oxygen ratio test. To perform the aneroid
closure test, proceed as follows:
1. Descend to 25,000 feet by using the
CHAMBER BLEED valve.
2. Ensure that the inlet pressure is as specified
on the Performance Test Sheet.
3. Setup a flow of 5.0 inches of H2O on the
OUTPUT FLOW manometer with OUTPUT
4. The aneroid closes between 28,000 and
32,000 feet, as indicated by no further advance
in altitude on the LOW RANGE altimeter.
5. Close the OUTPUT valve and descend to
sea level by using the CHAMBER BLEED valve.
6. If the regulator fails aneroid closure test
and/or oxygen ratio test, locate probable cause
using troubleshooting chart, table 12-13.
SAFETY PRESSURE AND PRESSURE
BREATHING TEST. This test determines if
100-percent oxygen is being delivered to the user
through the regulator between 30 and 50,000 feet.
Table 12-13.Troubleshooting (Oxygen Ratio/Aneroid Closure Tests)