Downloaded from https://www.everyspec.com MIL-STD-810D 19 July 1983 ... (3) Penetration of moisture through test item seals. (4) Release of water or water vapor from hydroscopic material within the test item. - c. Eromdure 111 - kmiva ted. Procedure III exposes the test item to more extreme temperature and humiditv levels than ‘thosefound in nature but for shorter durations. It is used to re~uce the time and cost of testing. This- procedure is used to identify potential problem areas, and the test levels are, for all practical purposes, fixed. . I-3.2 mo~w .t. . Related test conditions depend on the climate, duration, and test item configuration during shipping, storage, and deployment.
The variables common to all three procedures are the b temperature-humiditycycles, duration, and configuration”. These are discussed below.,,.Requirements documents may impose.or imply additional test conditions. The worst-case conditions should form the basis for selecting the test and test conditions to use. a. I.e@ite Dera m ture-hum&. The specific’test temperature-humidity values are ielected preferably from the requirements“documents. If this information is not available, determination of the test temperature-humidity valuea for procedures I and II can be based on the world geographical areas in which ‘the test item will be used, Plus any additional considerations.
Table 507,,.2-1includes the temperature and relative humidity conditions for three geographical categories where’high relative humidity conditions may be.of concern, and two related categories of induced conditions. Figures 507.2-1“and 507.2-2 are approximations.of.the cycles and are to be used if chamber control of table 507.2-I‘cyclesis difficultto achieve. The curves are constructed with consideration of chamber limitations. A description of each category follows. o (1) Hot-humid.
Severe (high) dewpoint conditions occur 10”to 15 times a year along a very narrow coastal atrip, probably less than 5 miles wide,’bordering bodies of water with high surface temperature, specifically the .PersianGulf and the Red,Sea. Most of the year these same areas experience hot-dry conditions. Due to the relatively small area in which these conditions occur; ,mosttypes of equipment,need,not be designed t.owithstand this environment. ,. (2) ~tant high humi~. Constant high humidity is found most often in tropical areas, although it occurs briefly or aeaionally in the . midlatitudes.
The conetant-high-humiditycycle occurs in heavily forested area?.where near1y constant temperature and humidity may prevail during rainy aeaaons with little (if any) solar radiation exposure. Tropical exposure in a tactical configuration or mode is likely to occur under a jungle canopy. .. Exposed materiel is likely to be constantly wet or damp for many days at a time. World areas where these conditions occur are the Congo and Amazon Basins, the jungles of Central America, Southeast Asia (including the East Indies), the north and east coasts of Australia, the east coast of Madagascar, and the Caribbean islands.
The conditions can exist for 25 to 30 days each month in the most humid areas of the tropics. The most significant variation of this cycle is its frequency of occurrence. In equatorial areas, it occurs 19 July 1983 507.2-3. METHOD 507.2