WARNING BECAUSE OF POSSIBLE VACUUM PUMP EXPLOSION, ONLY WATER- PUMPED NITROGEN, TYPE 1, CLASS 1, GRADE B, (FED. SPEC BB-N-411) WILL BE USED IN TESTING OXYGEN REGULATORS. USE ONLY NITRO- GEN FROM GRAY CYLINDERS MARKED NITROGEN OIL FREE IN WHITE LETTERS. TWO 3-INCH WIDE BLACK BANDS MARK THE TOPS OF THESE CYLINDERS. OXYGEN TEST STANDS CONTAIN A MERCURY MANOMETER. MERCURY IS A TOPIC METAL. AVOID BREATH- ING MERCURY VAPORS. AVOID CONTACT WITH SKIN OR CLOTH- ING. OVERLOAD TEST. To perform the overload test, proceed as follows: 1. Cap the regulator inlet and attach the regulator outlet to the short hose attached to piezometer (26) in the chamber. Ensure all test stand valves are in the secured position, then open the N₂ supply cylinder valve. NOTE: Ensure the regulator outlet and piezometer (26) are one inch apart. 2. Using the hose supplied with the test stand, connect LOW PRESS connection (19) to REF. TAP connection (21) in the chamber. 3. Ensure the FLOW SELECTOR valve (M) is in the REGULATOR position. 4. Adjust LOW PRESS. REGULATOR (N) so that regulated LOW PRESS. gauge (11) indicates 70 psig. NOTE: When the in-system leakage rotameters are used, an inlet pressure of 70 psig will normally be used, as this is the pressure used to calibrate the rotameters. 5. Place PRESS. SELECTOR valve (D) in the Hg position. 6. Slowly open LEAKAGE CONTROL valve (E) until 1.85 inches in Hg is indicated on Hg manometer (5). Maintain 1.85 inches of Hg for 2 minutes. If no leakage is indicated on HIGH RANGE LEAKAGE rotameter (B), turn LEAK- AGE SELECTOR valve (F) to the LOW RANGE position and check for leakage on the LOW RANGE LEAKAGE rotameter (7). The max- imum allowable leakage will be no more than the allowable leakage for each model shown on the performance test sheet. If the leakage is excessive, dispose of the regulator in accordance with your local directives. NOTE: A body leakage testis done on the model 900-002-025-05 regulator only. Refer to the NAVAIR 13-1-6.4, DEMAND VALVE LEAKAGE TEST. WARNING NEVER BLOCK THE OUTLET OF THE MINIATURE REGULATOR WHILE A PRESSURE IS APPLIED TO THE INLET. THIS WILL SERIOUSLY DAMAGE THE REGULATOR. NOTE: If a high reading is encountered during this test, make sure the pressure breathing aneroid is not screwed into the regulator housing too far before disposing of the regulator. Turn the pressure breath- ing aneroid counterclockwise out of the regulator housing and then recheck the readings. 7. Disconnect the hose from LOW PRESS connection (19) and REF TAP connection (21) in the altitude chamber. 8. Uncap the regulator inlet and connect the regulator inlet to N₂ input connection (18) in the altitude chamber. 9. Ensure PRESS SELECTOR valve (D) is in the Hg position. 10. Turn on the vacuum pump. 11. Turn INLET PRESS on/off valve (L) to ON slowly. 12. Using LOW PRESS REGULATOR (N), apply 110 psig to the regulator inlet. The pressure will be indicated on N₂ INPUT PRESS gauge (27). 13. Open OUTPUT valve (C) to draw a flow through the regulator, then close valve (c). 14. Place PRESS SELECTOR valve (D) in H₂O position. Observe the PRESS/SUCTION manometer (4) for 5 minutes. The pressure must not exceed 2.5 inches of H₂O. After the 5 minute period, read manometer (4) and enter the reading on the performance test stand. If the leakage is excessive, dispose of the regulator. 15. Leave the positions of all controls and connections unchanged. SAFETY PRESSURE TEST. To perform the safety pressure test, proceed as follows: 1. Adjust LOW PRESSURE REGULATOR (N) to 50 psig as indicated on N₂ INPUT PRESS gauge (27). 12-4