MIL-STD 810 High Temperature Testing
MIL-STD 810 high temperature testing helps evaluate the effects of high temperature conditions on performance, integrity, and material safety. This method is best used on material likely to be deployed where temperatures are higher than standard ambient. According to MIL-810H high temperature, all testing should be performed in a high temperature testing lab.
Use of this method should be limited to evaluating the effects of short-term, even, distributions of heat throughout the material. Short-term refers to months as opposed to years. This test is not practical for evaluating degradation due to regular long-term exposure to high temperatures with synergetic. For such aging effects, test in the natural environment.
This method is also not practical for evaluating material in a high temperature environment where solar radiation produces significant thermal gradients. Generally this method should not be used to evaluate actinic effects, nor the effects of streamlined heating without considerable tailoring.
Keystone Compliance is a fully equipped high temperature laboratory with significant experience in Method 501.7 of MIL-STD 810 high temperature. The following information is extremely technical in nature, it provides a summary of MIL-810 high temperature testing. This information is drawn from MIL-STD 810H high temperature and MIL-STD 810G high temperature section.
What are the Effects of High Temperature Environments According to MIL-810 Temperature?
Exposure to hot environments may temporarily or permanently impair performance by changing physical properties or dimensions of the material(s). The following are examples of problems that could result from high temperature exposure that may relate to the material being tested. Consider the following typical problems to help determine if MIL-STD 810 temperature testing is appropriate. This list is not intended to be exhaustive.
- 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 degarde.
- 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.
- Shortening of operation lifetime.
- Solid pellets or grains separate.
- High pressures created within sealed cases (projectiles, bombs, etc.).
- Faster 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 or coatings (i.e. VOCs, CO, and Phthalates).
- Failure of adhesives.
What Should be Considered When Selecting the Procedure for MIL-STD-810 Temperature Testing?
There are multiple considerations selecting procedures for high temperature compliance testing. Consider the natural exposure circumstances, whether they are ambient or induced. Also examine the operational purpose of the material. Then determine if the operational purpose of the material has been met by examining the test data.
Look at the procedure sequence. If both the storage and operation procedures are to be applied, perform Procedure I before Procedure II. Consider using Procedure III in lieu of Procedure II for unique cases. In these cases, material in its operational configuration is not operational and is exposed to solar heating.
Consider combining Procedures I and II when using constant temperature. When attempting to combine procedures it is preferable to conduct Procedure II before Procedure I. Then repeat Procedure II. The best high temperature testing should be conducted in series with no return to ambient conditions until test completion.
Examine the other significant adjacent heat sources that could affect the material. These sources can be motors, engines, power supplies, other electronics, or exhaust air.
What are the Differences Among Procedures for High Temperature Compliance Testing?
According to the MIL-810G high temperature and MIL-810H temperature section, there are three different operational procedures. The storage procedure assesses the effects of high temperature storage on subsequent material performance. The operation procedure assesses the effects of high temperatures during performance. The tactical-standby to operational procedure evaluates the ability of hot, sun-soaked material to quickly be operational.
Procedure I, storage, is used to investigate how high temperatures during storage affect the material. This test procedure includes exposing the material to high temperatures (and low humidity) that may be encountered in a storage situation. This is followed by an operational test at ambient conditions.
Procedure II, operation, is used to investigate how high ambient temperatures may affect materiel performance during operating. There are two ways to perform Procedure II. One, expose the item to cyclic chamber conditions with it operating either steadily or during the period of highest item temperature. Two, expose the test item to a constant temperature and operate the test item when its temperature stabilizes.
Procedure III, tactical-standby to operational, is not a substitute for solar radiation. This procedure evaluates the performance at the operating temperatures after presoaking at not operational temperatures. Since actinic effects and directional heating are not applicable, consider applying this procedure when material is in an enclosed environment.
For example, aircraft and ground vehicles with closed transparent or translucent areas can develop high internal temperatures before equipment operation. This is due to solar heating. Enclosures such as communications shelters may require immediate operation after being exposed to solar heating.
These are not items in storage or transit situations. Rather they are items in the operational configuration that must be operational in a relatively short period of time. Usually, the “cooling” option refers to opening the enclosed areas and allowing the ambient air to begin cooling the interior areas.
| Design Type | Location | Ambient Air °C (°F) | Induced °C (°F) |
|---|---|---|---|
| Basic Hot (A2) | Many areas, extending outward from southwestern United states, northwestern Mexico, central and western Australia, Saharan Africa. As well as South America, southern Spain, and southwest and south-central Asia. | 30-43 (86-110) | 30-63 (86-145) |
| Hot Dry (A1) | Southwest and south-central Asia, southwestern United States, Saharan Africa, central and Western Australia, and northwestern Mexico. | 32-49 (90-120) | 33-71 (91-160) |
What High Temperature Lab Should I Trust?
Keystone Compliance has been recognized as one of the best High temperature labs in the country. We are equipped to provide high temperature certifications for commercial, military, and aerospace products. Contact us to learn why so many manufacturers rely on Keystone Compliance’s temperature testing services for their thermal testing needs.
There have been several versions of high temperature testing procedures in MIL-STD-810 high temperature testing. Below is a list of each version and the appropriate method number:
- MIL-STD-810A Test Method 501.1 High Temperature Testing
- MIL-STD-810B Test Method 501 High Temperature Testing
- MIL-STD-810C Test Method 501.1 High Temperature Testing
- MIL-STD-810D Test Method 501.2 High Temperature Testing
- MIL-STD-810E Test Method 501.3 High Temperature Testing
- MIL-STD-810F Test Method 501.4 High Temperature Testing
- MIL-STD-810G Test Method 501.5 High Temperature Testing
- MIL-STD-810H Test Method 501.7 High Temperature Testing