Downloaded from https://www.everyspec.com MIL-STD-81OC 3.3 Procedure III. (This is a test for determining slight leakage as well as gross leakage. This procedure may also be used for equipment which is normally pressurized in use.) 3.3.1 Test conditions. The temperature of the liquid and test item shall be 23° *1O”C (73° f18rF). 3.3.2 Performance of test. The test item shall be completely immersed in a suitable liquid such as water so that the uppermost part of the test item is 2 *1 inches below the surface of the’liquid.
The absolute pressure of the air above the liquid shal1 be reduced to 1, 19, or 25 inches of mercury (absolute)or other values as specified in the equipment specification,and maintained for 1 minute, or until air bubbles substantially cease to be given off by the liquid, whichever is the longer time. The absolute pressure above the liquid shall then be increased to 2.5, 20 or 26 inches of mercury, respect- ively, and maintained for 60 minutes. 3.3.3 Failure criteria. Bubbles coming from within the equipment shall be considered a leakage; however, bubbles which result from trapped air on the various exterior surfaces of the test item shal1 not be considered a leak. 3.4 Procedure IV.
(For equipment which is normally pressurized.) 3.4.1 Test conditions. The temperature of the liquid, pressurizing gas, and the test item shall be 23 flO°C (73” t18°F). The gas used for pressuring (e.g., air, nitrogen, or helium) shall be clean and dry with a dewpoint of at least,-32° C (-25°F). 3.4.2 Performance of test. The equipment shall be completely immersed in a suitable liquid such as.water so that the uppermost part of the test item is 2 *1 inches below the surface of the liquid.
The equipment shall be intetially pressurized from a minimum to 125 percent of the maximum operating pressure, as specified in the equipment specification and maintained for a minimum of 60 minutes at each pressure. 3.4.3 Failure criteria. Bubbles coming from within the equipment shal1 be considered a leakage; however, bubbles which result from trapped air on the various exterior surfaces of the test item shal1 not be considered a leak. NOTE: In lieu of procedures III or IV, a helium or halogen l;ak detector (equal or superior in sensitivity to these immersion test methods) may be used upon approval of the procuring activity. METHOD 512.1 512.1-2