Temperature Testing Archives - Delserro Engineering Solutions

MIL-STD-810 Low Temperature Testing

MIL-STD 810, Method 502 Low Temperature Testing is used to evaluate the effects of low temperatures on cold storage, operation, and manipulation. Method 502 is applicable for testing products that will be exposed to cold temperatures during their life cycle. The latest revision is Method 502.7 from MIL-STD-810H.

MIL-STD-810 low temperature testing is not intended to simulate a high altitude, low temperature environment associated with an unpressurized aircraft at altitude. However, it may be used in combination with Method 500.6 to simulate a high altitude, low temperature environment.

Some of the Effects of Low Temperature Environments are:

Hardening and embrittlement of materials.
Binding of parts from differential contraction of dissimilar materials.
Loss of lubrication and lubricant flow due to increased viscosity.
Changes in electronic components (resistors, capacitors, etc.).
Changes in performance of transformers and electromechanical components.
Stiffening of shock mounts.
Cracking, change in impact strength, and reduced strength.
Effects due to condensation and freezing of water in or on the materiel.

Method 502 Has Three Procedures Starting with Low Temperature Storage:

Procedure I – Storage. Procedure I is used to evaluate products that are stored at Low temperatures. After the Low temperature storage test is completed, an operational test at ambient conditions is performed.
Procedure II – Operation. Procedure II is used to determine how well an item will operate in low temperature environments. Operation during this procedure assumes minimum contact by personnel.
Procedure III – Manipulation. Manipulation is used to investigate the ease with which the materiel can be assembled, operated, and disassembled by personnel wearing heavy, cold-weather clothing. In addition, this could also include maintenance procedures.

Low Temperature Test Parameters and Procedures Under MIL-STD-810

First, identify the Low temperature test parameters and applicable procedures. DES can help determine the appropriate low temperature test conditions based on the equipment’s intended use. Consider the following cold temperatures in various world-wide locations from Table 502.7-I. (MIL-STD-810H):

Design Type	Location	Ambient Air Temperature ^oC(^oF)	Induced Environment Temperature (Storage & Transit) ^oC(^oF)
Basic Cold (C1)	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); Northern Scandinavia; Northern Asia (some areas), High Elevations (Northern and Southern Hemispheres); Alps; Himalayas; Andes	-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)

Source: Table 502.7-I. (MIL-STD-810H)

The recommended test duration from MIL-STD-810H is four hours after stabilization for nonhazardous or non-safety-related (non-life-support type) material. Munitions, rubber and plastics may continue to deteriorate following low temperature stabilization. For these items, a minimum duration of 72 hours following temperature stabilization is recommended. For restrained glass, ceramics, and glass-type products (such as those used in optical systems, laser systems, and electronic systems) a minimum storage period of 24 hours following temperature stabilization is recommended.

Advantages of MIL-STD-810H Low Temperature Testing with DES:

DES excels in MIL-STD-810H Low Temperature Testing. With our lab’s accreditation and equipped with advanced temperature chambers, we ensure your equipment meets the cold-weather performance standards required by MIL-STD-810H. Some of the reasons that DES is trusted by many companies for MIL-STD-810H Low Temperature Testing are:

DES has extensive experience running MIL-STD-810 Method 502.7 Low Temperature tests
DES’s lab is A2LA accredited to MIL-STD-810, Method 502 Low Temperature Testing
DES is trusted by many military manufacturers to perform their testing
DES has numerous temperature chambers capable of performing MIL-STD-810 Low temperature compliance testing

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MIL-STD-810 High Temperature Testing

MIL-STD 810, Method 501 High Temperature Testing is used to evaluate the effects of high temperature conditions on performance, materials, and integrity. Method 501 is applicable for temperature testing products that are deployed in areas where temperatures (ambient or induced) are higher than standard ambient. Note, the latest revision of this method is 501.7 from MIL-STD-810H.

Method 501 is limited to evaluating the effects of relatively short-term (months, as opposed to years), even distributions of heat throughout the test item. This method is not typically practical for evaluating materials where solar radiation produces thermal gradients or photochemical effects. Method 505 is used to test the effects of solar radiation. It is also not practical to evaluate degradation that occurs from continuous long-term exposure to high temperatures where synergetic effects may be involved.

The following are typical failures that could occur from products used in high temperature environments.

Parts bind from the differential expansion of dissimilar materials.
Lubricants become less viscous; joints lose lubrication by the outward flow of lubricants.
Materials change in dimension.
Packing, gaskets, seals, bearings, and shafts become distorted, bind, and fail causing mechanical failures.
Gaskets display permanent sets.
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 lifetimes.
High pressures are created within sealed cases (batteries, etc.).
Discoloration, cracking, or crazing of organic materials.
Out-gassing of composite materials or coatings.
Failure of adhesives.

MIL-STD-810 Method 501 Tests: High Temperature Procedures

Procedure I – Storage. Procedure I is for testing products that are stored at high temperatures. After the high temperature storage test is completed, an operational test at ambient conditions is performed. Procedure I can be either a cyclic temperature test or a constant temperature test.
Procedure II – Operation. Procedure II is used to investigate how high temperatures could affect the performance of items while they are operating. Temperature Procedure II can be performed as either a cyclic temperature test or a constant temperature test.
Procedure III – Tactical-Standby to Operational. This temperature procedure evaluates the material’s performance at normal operating temperatures after being presoaked at high non-operational temperatures. An example of Procedure III is a product that is stored in an enclosed environment that develops high internal temperatures before being removed and then operated in a relatively short period of time.

What is the procedure for MIL-STD-810 High Temperature Testing?

First, identify the high temperature levels, test conditions, and applicable procedures. DES can help determine the appropriate temperature ramp rates and durations of the tests based on the equipment’s intended use and the operating environmental conditions. Consider the following climatic temperatures from Table 501.7-I. (MIL-STD-810H):

Design Type	Location	Ambient Air ^oC (^oF)	Induced² ^oC (^oF)
Basic Hot (A2)	Many parts of the world, extending outward from the hot dry category of southwestern United States, northwestern Mexico, central and western Australia, Saharan Africa, South America, Southern Spain, and southwest and south central Asia.	30 – 43 (86 – 11)	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)

Table 501.7-I from MIL-STD-810H

Next, determine whether a constant temperature test or a cyclic temperature test is appropriate. Constant temperature testing is used only for items situated near heat-producing equipment or when it is necessary to verify the operation of an item at a specified constant temperature. The duration for constant temperature test temperature is at least two hours following test specimen stabilization.

For cyclic exposure, there are two 24-hour cyclic profiles contained in Tables 501.7-II and 501.7-III. The number of cycles for the Procedure I storage test is a minimum of seven to coincide with the one percent frequency of occurrence of the hours of extreme temperatures during the most severe month in an average year at the most severe location. The minimum number of cycles for the Procedure II operational testing is three. This number is normally sufficient for the test item to reach its maximum response temperature.

You can trust the DES MIL-STD-810 High Temperature Testing lab

Advantages with DES :

DES is A2LA accredited to MIL-STD-810, Method 501 High Temperature Testing
DES has extensive experience running MIL-STD-810 Method 501.7 high temperature Tests
DES has multiple temperature chambers capable of performing MIL-STD-810 high temperature compliance testing

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Qualification Testing on Aerospace Connectors

DES recently performed qualification testing on aerospace connectors which involved combined temperature and sinusoidal vibration testing, random vibration testing and shock testing. Combined temperature and sinusoidal vibration tests were performed per EIA 364-28F. EIA 364-28F required test conditions of 10-2000 Hz, 20G maximum acceleration sweeps at temperatures of -54°C and 200°C over the course of 4 hours per axis. Random vibration tests were also performed per EIA 364-28F. Random vibrations at 50-2000 Hz, 46.3 Grms were applied to the connectors for 8 hours per axis. The random vibrations were applied at room temperature. Finally, the connectors were subjected half sine shocks per EIA 364-27C. The shock requirements were three shocks per polarity, per axis at 300G over the duration of 3msec. A sample shock plot can be seen in Figure 1.

Sample Shock Testing Chart — **Figure 1 – Sample Shock Test Plot**

Continue reading Qualification Testing on Aerospace Connectors →

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ASTM D7386-12 Package Testing

DES recently performed package testing per ASTM standard, ASTM D7386-12.

Continue reading ASTM D7386-12 Package Testing →

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Thermal Shock Testing – Temperature Cycling

Thermal shock testing also called temperature shock testing or temperature cycling exposes products to alternating low and high air temperatures to accelerate failures caused by repeated temperature variations during normal use conditions. The transition between temperature extremes occurs very rapidly during thermal shock testing, greater than 15 °C per minute. Alternatively, temperature cycle testing uses slower rates of change between high and low temperatures. The failure acceleration rate for thermal shock testing is determined by the Coffin-Manson equation as previously discussed in DES’s blog article Temperature Cycling Testing: Coffin-Manson Equation.

Equipment with single or multiple chambers may be used to perform thermal shock testing. When using single chamber thermal shock equipment, the products or samples remain in one chamber and the chamber air temperature is rapidly cooled and heated. This usually results in a slower rate of change in the product response temperature as the entire chamber must be cooled down and heated up. However larger products can be tested in single compartment chambers. Some equipment uses separate hot and cold chambers with an elevator mechanism that transports the products between two or more chambers. This results in a more rapid rate of change in the air temperature. However, there is a limit to the size and weight than can be put in a chamber with an elevator mechanism. DES has both types of chambers for thermal shock testing.

Continue reading Thermal Shock Testing – Temperature Cycling →

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Case Study: Combined Temperature & Vibration Testing of Automotive Mass Air Flow Sensors

Mass Air Flow Sensors (MAFS) are used to measure the mass flowrate of air entering engines in newer model cars. The mass air flow information is transmitted to the engine control unit (ECU) to balance and deliver the correct amount of fuel mass to the engine. These sensors operate in a very harsh environment, a car engine compartment! Testing their reliability and proving their durability is a very difficult task.

: Mass Air Flow Sensors (MAFS) Combined Temperature Vibration Testing

DES was awarded multiple contracts to perform combined temperature and vibration reliability testing of Mass Air Flow Sensors from various automotive part manufacturers and from a major auto parts supplier.

Continue reading Case Study: Combined Temperature & Vibration Testing of Automotive Mass Air Flow Sensors →

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