Use high temperature tests to obtain data to help evaluate effects of high temperature conditions on materiel safety, integrity, and performance. Use this method to evaluate materiel likely to be deployed in areas where temperatures (ambient or induced) are higher than standard ambient.
Effects of high temperature environments.
High temperatures may temporarily or permanently impair performance of materiel by changing physical properties or dimensions of the material(s) of which it is composed. The following are examples of problems that could result from high temperature exposure that may relate to the materiel being tested. Consider the following typical problems to help determine if this method is appropriate for the materiel being tested. This list is not intended to be all-inclusive.
- Parts bind from differential expansion of dissimilar materials.
- Lubricants become less viscous; joints lose lubrication by outward flow of lubricants.
- Materials change in dimension, either totally or selectively.
- Packing, gaskets, seals, bearings and shafts become distorted, bind, and fail causing mechanical or integrity failures.
- Gaskets display permanent set.
- Closure and sealing strips deteriorate.
- Fixed-resistance resistors change in values.
- Electronic circuit stability varies with differences in temperature gradients and differential expansion of dissimilar materials.
- Transformers and electromechanical components overheat.
- Operating/release margins of relays and magnetic or thermally activated devices alter.
- Shortened operating lifetime.
- Solid pellets or grains separate.
- High pressures created within sealed cases (projectiles, bombs, etc.).
- Accelerated burning of explosives or propellants.
- Expansion of cast explosives within their cases.
- Explosives melt and exude.
- Discoloration, cracking or crazing of organic materials.
- Out-gassing of composite materials.
6. MIL-STD-810G, Method 502.5, Procedure I and II - Low Temperature
Use low temperature tests to obtain data to help evaluate effects of low temperature conditions on materiel safety, integrity, and performance during storage, operation, and manipulation.
Use this method to evaluate materiel likely to be deployed in a low temperature environment during its life cycle and the effects of low temperature have not been assessed during other tests (e.g., a temperature-altitude test).
While all procedures involve low temperatures, they differ on the basis of the timing and nature of performance tests.
- Procedure I - Storage. Use Procedure I to investigate how low temperatures during storage affect materiel safety during and after storage, and performance after storage.
- Procedure II - Operation. Use Procedure II to investigate how well the materiel operates in low temperature environments. For the purpose of this document, operation is defined as excitation of the materiel with a minimum of contact by personnel. It does not exclude handling (manipulation).
7. MIL-STD-810G, Method 503.5, Procedure I - Thermal Shock
