Downloaded from https://www.everyspec.com MIL-STD-81OC b Step 6 - Maintain the internal chamber temperature at’40.5° C (105”F) and the relative humidity at 90 percent for 16 hours. Step 7 - Gradually decrease the internal chamber temperature to 21° C [70”F) and increase the relative humidity to 95 percent in 2 hours. Step 8 - Maintain the internal chamber temperature at 21° C (70° F) and the relative humidity at 95 percent for 4 hours. Step 9 - Repeat steps 4, 6, 7, and 8 for a total of 20 cycles (480 hours). Take measurements as specified in the equipment specification. Prior to measurements, accumulated moisture may be removed by turning the test item upside down or “shaking.
Wiping is not permitted. Figure“507.1-4 is an outline of the humidity cycle for this procedure. Step 10 - After completion of step 9 cycling, operate the test item adjusting for optimum performance only as permitted in step 5 note, and inspect the test item to obtain results in accord- ance with General Requirements, 3.2 within 1 hour., 4. :?R~ . The following details shall be specified in the equipment speclflcatlon: a. Procedure number b. Pretest data required c. Failure.criteria d. Periods at which measurements are to be taken e. Method for determining purity of water if a more precise method is desired. (An ‘alternateto pH criteria is to perform a conductivitymeasurement.
The maximum acceptable value would be that resistance which is equivalent to 3.5 parts per million total ionized solids.) f. If test item must be exposed to extreme temperature prior to test [procedure 1). g. Number of cycles if other than 20 (procedureV, step 9). h., Whether cycle is to be limited to’first 24”hours (procedure II, step 6]. METHOD’507.1 507.1-9