FLOW SUCTION TEST.- This test determines how much suction will be required by the user to achieve or receive a given amount of oxygen or air/oxygen mixture through the regulator. To perform the flow suction test, proceed as follows:

1. Disconnect the hose from the LOW PRESSURE connection and REFERENCE TAP connection inside the altitude chamber.

2. Turn vacuum pump ON.

3. Ensure that the PRESSURE SELECTOR Valve is in the H2O position.

4. Ensure that the regulator diluter control lever is in the 100-percent OXYGEN position.

5. Ensure that the INLET PRESSURE ON/OFF valve is ON.

6. Ensure that the regulator supply valve control lever is in the ON position.

7. By using the LOW PRESSURE REGU-LATOR, set the inlet pressure at each inlet pressure specified on the Performance Test Sheet.

8. By using the OUTPUT valve, set flows specified in the Performance Test Sheet on the OUTPUT manometer. Readings must be recorded with the regulator diluter control lever in both NORMAL and 100-percent OXYGEN positions for each outlet flow specified on the Performance Test Sheet. Suction values will be displayed on PRESSURE/SUCTION manometer. With no suction on the regulator (OUTPUT valve closed), maximum flow through regulator should not exceed 0.01 lpm. This will cause a slight rise in the PRESSURE/SUCTION manometer reading. Record readings on the Performance Test Sheet.

9. Close OUTPUT valve.

10. If the regulator fails the flow suction test, locate the probable cause by using the troubleshooting chart in table 12-12.

Table 12-11.-Troubleshootig (Second Stage Relief Valve Test)

Table 12-12.-Troubleshooting (Flow Suction Test)

OXYGEN RATIO TEST.- This test determines 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 position.

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 (B 1), 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 manometer, and record all readings on the Performance Test Sheet.

6. Continue the test for each specified altitude and output flow shown on the Performance Test Sheet.

7. Close OUTPUT valve and INPUT valve. Descend to 27,000 feet using CHAMBER BLEED valve.

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.