(1) Storage test: The test temperatures for storage test exposures should include cyclic conditions that are derived from the natural diurnal cycles. The cycles provided in tables 501.3-1 and 501.3-11 and information in I- 3.2a(3) are the extreme meteorological and induced diurnal cycles for major world areas. The temperature extremes given are based on a frequency of one percent of the hours during the most severe month in the most severe part of the area encompassed by the climatic region of interest. The map in General Requirements, figure 5, shows the boundaries I of the areas of concern. The chamber air temperature and humidity conditions can be derived or calculated from the analysis of the storage situation (1-3.1,3.1) and the cycles provided in tables 501.3-1 and 501.3-11 and in I-3.2a(3). The values given in the tables represent the conditions of air within the storage place or adjacent to the test item. Derivation of the actual test temperatures must consider the thermal path to the test item, type of heat transfer, mass of the test item in relation to the mass of the surrounding air, and other empirical and thermal properties of the test item.
Defines standard
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| File | MIME type | Size (KB) | Language | Download | |
|---|---|---|---|---|---|
| MIL STD- Environmental Test Methods and Engineering Guidelines (1993).PDF | application/pdf | 37.45 MB | English | DOWNLOAD! |
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Introduction
1-1 PURPOSE.
Low-pressure (altitude) chamber tests are performed to determine if materiel can withstand, and operate in, a low-pressure environment, and withstand rapid pressure changes.
I-2 ENVIRONMENTAL EFFECTS. Examples of some problems that could occur as a result of exposure to reduced pressure are:
a. Leakage of gases or fluids from gasket-sealed enclosures.
b. Rupture or explosion of sealed containers.
c. Change in physical and chemical properties of low-density materials.
d. Erratic operation or malfunction of equipment resulting from arcing or corona.
e. Overheating of equipment due to reduced heat transfer.
f. Evaporation of lubricants.
g. Erratic starting and combustion of engines.
h. Failure of hermetic seals.