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MIL-STD-810 Low Temperature Testing

MIL-STD 810 low temperature evaluates the effects of low temperatures on the integrity, safety, and performance of material during storage and use. This method is best for evaluating material that will likely be exposed to a low temperature environment during its life cycle. This test is not meant to stimulate the high altitude, low temperature environment of an unpressurized aircraft at altitude. However, it may be used with Method 500.6 to stimulate a high altitude, low temperature environment.

Keystone Compliance is one of the best low temperature testing labs, with significant MIL-810 low temperature testing experience. Our test engineers understand the requirements of MIL-STD 810H low temperature and MIL-STD 810G low temperature testing. The following is a summary of the requirements of MIL-810H low temperature testing and MIL-810G low temperature testing.

What Are the Effects of Low Temperature Environments on Material?

Low temperatures have adverse effects on almost all basic material. Exposure of material to low temperatures may temporarily or permanently impair operation by changing physical properties.  Consider low temperature tests whenever material will be exposed to temperatures below standard ambient. Consider the following typical problems to help determine if this test method is appropriate for the material being tested.

  • Hardening and embrittlement of materials.
  • Binding of parts from differential contraction of dissimilar materials.
  • The different rates of expansion of different parts in response to temperature transients.
  • Loss of lubrication and lubricant flow due to increased viscosity. In addition, fuels may gel at low
  • temperature
  • Changes in electronic components (resistors, capacitors, etc)
  • Changes in performance of transformers and electromechanical components.
  • Stiffening of shock mounts
  • Cracking of explosive solid pellets or grains, such as ammonium nitrate.
  • Cracking and crazing, change in impact strength, and reduced strength.
  • Static fatigue of restrained glass
  • Effects due to condensation and freezing of water in or on the material.
  • Decrease in dexterity, hearing, and vision of personnel wearing protective clothing.
  • Change of burning rates

What are the Different Procedures for Low temperature Certification Testing?

While all procedures involve low temperatures, they differ on the basis of the timing and nature of performance tests. Procedure I, storage, investigates how low temperatures during storage affect material safety during and after storage, and performance after storage. Procedure II, operation,  investigates how well the material operates in low temperature environments.

For our purposes, operation is defined as excitation of the material with a minimum of contact by personnel. It does not exclude handling a.k.a manipulation. Procedure III, manipulation, investigates how well material can be assembled, operated, and disassembled by personnel wearing cold-weather clothing. In addition, this could also include maintenance procedures.

How is MIL-810 Temperature Testing Performed Based on Projected Climate Conditions?

The following table can be used to determine the test temperature for times when the test item is only used for specific regions. The air temperature criteria shown is based on a 1% frequency-of-occurrence of the hours during an average year at the most severe location in the region. However, air temperature criteria for severe cold is based on a 20 percent frequency of occurrence. The values shown represent the range of the diurnal cycles, for this Method, the lowest value in each range is usually considered.

For materials stored or operated worldwide, the absolute cold temperature and frequency of the given cold condition is considered when selecting temperatures. If frequency is not considered, there is a risk of creating an unrealistic test condition. Frequency-of-occurrence values are the percent of total hours the given cold temperatures is equaled or exceeded, in the most extreme month and area in the world.

Take, for example the 20% frequency of occurrence of -51 °C. This means, during an average year, it will be -51 °C or lower for 20% of the hours of the most extreme month. A 20% frequency of occurrence is used for most applications with normal development cost considerations. However, to satisfy specific applications or test requirements, other more extreme values may be appropriate.

Table 502.7-I. Summary of Low Temperature Cycle Ranges.

 

DESIGN TYPE

 

LOCATION

                        TEMPERATURE
Ambient Air 
°C (°F) 
Induced Environment 
(Storage & Transit)
          °C (°F)
Basic Cold (CI)

Most of Europe: Northern contiguous US; Costal Canada; High-latitude coasts (e.g., southern coast of Alaska);

High elevations in lower latitudes

-21 to -32
(-5 to -25)
-25 to -33
(-13 to -28)
Cold (C2)

Canada, Alaska (excluding the interior): Greenland (excluding the “cold pole”)

Northern Scandinavia;

Northern Asia (some areas)

High Elevations (Northern and Southern Hemispheres); Alps; Himalayas; Andres

-37 to -46
(-35 to -50)
-37 to -46
(-35 to -50)
Severe Cold (C3)Interior of Alaska; Yukon(Canada); Interior of Northern Canadian Islands; Greenland ice cap; Northern Asia
-51
(-60)
-51
(-60)

What is the Appropriate Duration of Exposure?

The duration of exposure to low temperature may be a factor in material safety, integrity and performance. MIL-STD 810 temperature lists three categories of material to be considered when thinking about duration.

The first type of material is Non Hazardous or non-safety-related (non-life-support type) material. Most material in this category will not experience deterioration following temperature stabilization at low temperatures. Rubber and plastics are possible exceptions to this. Following temperature stabilization, use a storage period of four hours for this material if no other value is available.

The second type of material is explosives, munitions, rubber and plastics, etc. These items may continue to deteriorate following temperature stabilization. Consequently, it is necessary to test them at low temperatures for long periods of time. Use a minimum storage period of 72 hours following temperature stabilization of the test item.

The third type of material is restrained glass; glass-type products that are mounted or restrained in specific positions may experience static fatigue. A more extended period of low temperature may be required to induce this phenomenon. In some cases, glass will only reveal static fatigue to low temperature after previously being subjected to other environments. Use a minimum storage period of 24 hours following temperature stabilization of the test item.

Where is the Best Low Temperature Lab for MIL-STD-810 Temperature Testing?

Keystone Compliance has been recognized as one of the best low temperature laboratories in the country. Our experts understand the requirement of MIL-810H temperature testing.  Contact us to learn why so many manufacturers rely on Keystone Compliance’s testing services to meet their compliance testing needs.

There have been several versions of low temperature testing procedures in MIL-STD-810 low temperature testing. Below is a list of each version and the appropriate method number: