507.6-1 ABSORPTION
The accumulation of water molecules within material. The quantity of water absorbed depends, in part, on the water content of the ambient air. The process of absorption occurs continuously until equilibrium is reached. The penetration speed of the molecules in the water increases with temperature.
1.1 Purpose
The purpose of this Method is to determine the resistance of materiel to the effects of a warm, humid atmosphere.
1.2 Application
This Method applies to materiel that is likely to be stored or deployed in a warm, humid environment, an environment in which high levels of humidity occur, or to provide an indication of potential problems associated with humidity. Although it is preferable to test materiel at appropriate natural environment sites, it is not always practical because of logistical, cost, or schedule considerations. Warm, humid conditions can occur year-round in tropical areas, seasonally in mid-latitude areas, and in materiel subjected to combinations of changes in pressure, temperature, and relative humidity. Often materiel enclosed in non-operating vehicles in warm, humid areas can experience high internal temperature and humidity conditions. Other high levels of humidity can exist worldwide. Further information on high temperatures and humidity is provided in AR 70-38 (paragraph 6.1, reference a), MIL-HDBK-310 (paragraph 6.1, reference b), or NATO STANAG 4370, AECTP 230 (paragraph 6.1, reference c). See also Part Three of this Standard.
1.3 Limitations
This Method may not reproduce all of the humidity effects associated with the natural environment such as long-term effects, nor with low humidity situations. This Method does not attempt to duplicate the complex temperature/humidity environment but, rather, it provides a generally stressful situation that is intended to reveal potential problem areas in materiel. This Method includes natural and induced temperature/humidity cycles (for guidance purposes) for identified climatic categories, but these cycles cannot replicate naturally-occurring environments. Testing in the natural environment, whenever practical, may provide more valuable results. Specifically, this Method does not address:
- a. Condensation resulting from changes of pressure and temperature for airborne or ground materiel.
- b. Condensation resulting from black-body radiation (e.g., night sky effects).
- c. Synergistic effects of solar radiation, humidity, or condensation combined with biological and chemical contaminants.
- d. Liquid water trapped within materiel or packages and retained for significant periods.
- e. Evaluating the internal elements of a hermetically sealed assembly since such materiel is air-tight.