MIL-STD-962D
w/CHANGE 2
MIL-STD-202G
w/CHANGE 1
METHOD 112E
2. TEST CONDITIONS.
2.1 Selection. There are six test conditions (A, B, C, D, E, and F) in this method. Test conditions A and B utilize oil as a means to detect gross leaks by the observation of bubbles. Both of these tests will detect leaks of a nominal value of 10-5 atm cm3/s. Test condition B is used to test parts which will not withstand the temperature required in test condition A. Test condition C detects fine leaks by using a tracer gas and apparatus to measure a leakage rate (R1) to a nominal of 10-8 atm cm3/s. The apparatus can be calibrated for any leakage rate within its range. Test condition D utilizes a fluorocarbon liquid at 125°C ±5°C at ambient pressure and detects gross leaks by the observation of bubbles. This latter test condition provides an alternate gross leak test to test condition A. Test condition E utilizes two fluorocarbon liquids; one under pressure followed by the other at 125°C ±5°C at room ambient pressure and detects gross leaks by the observation of bubbles. This test condition provides a measure of leakage rate of a nominal value of 10-5 atm cm3/s. Test condition F utilizes a fluorocarbon liquid and a fluorocarbon vapor detector to detect gross leaks. Test condition F provides a measure of leakage rate of a nominal value of 10-5 atm cm3/s. Both test conditions C and F require more expensive commercial equipment and trained personnel, but the equipment provides automatic and quantitative readings. The selection of a test condition to perform the seal test depends on the state of the art of component part manufacturing, the leakage rate which can be tolerated for the desired reliability, the frequency of testing, range of test conditions, cavity size, and whether the testing is to be on a 100 percent production or on a periodic basis. The individual specification shall specify the test condition letter required. When test condition C is specified, the procedure number (see 5.4) and the degree of leakage rate sensitivity required shall be included. The following is included as a sensitivity and applicability guide:
Test condition A (bubble test - mineral oil or peanut oil at 125°C ±3°C). Use when a nominal sensitivity of 10-5 atm cm3/s is sufficient.
Test condition B (bubble test - silicone oil at room ambient temperature 25°C ±2°C), with a vacuum resulting in an absolute pressure of not greater than 1.5 inches of mercury (not greater than 38.1 torr). Use to test parts which cannot withstand the temperature of test condition A, and when a nominal sensitivity of 10-5 atm cm3/s is sufficient.
Test condition C (tracer gas test). Use when a nominal sensitivity of 10-8atm cm3/s is sufficient.
FIGURE 8. Example of change for standard containing individual tasks, requirements, or test methods - Continued.
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