• GJB 150.25A-2009 standardpurposeSimulated military equipment inHigh altitude areas or airborne environmentsPossible Encounters in the MiddleLow temperature, low pressure, and high humidityThe comprehensive environmental conditions. Assessment under such complex stress:

1. The working performance of the equipmentWill there be functional failure or performance degradation.

2. Physical and chemical properties of materialsWhether the sealing, insulation, and mechanical strength have deteriorated.

3. Potential defects of equipmentInternal condensation, overheating of components, and evaporation of lubricants caused by respiratory effects.

• Scope of Application：

• InPlateau regionEquipment for storage and use.

• InInside the aircraft cabin(Non sealed cabin) orExternal mountingThe equipment.

• Any military product that may experience low temperature, low pressure, and humid and hot environments simultaneously.

2、 Test type

The standard mainly includes two types of tests:

1. Storage/Air Transport Test：

• purposeAssess the ability of equipment to withstand a comprehensive temperature humidity altitude environment in non working conditions (such as transportation by air to high-altitude battlefields).

• featureEquipment during the experimental processnot workingThe main assessment is its physical and chemical stability, and after the experiment, its functionality is checked to see if it is normal.

2. Work Test：

• purposeAssess the performance stability of the equipment in a comprehensive environment of temperature humidity height under working conditions.

• featureEquipment during the experimental processIn working conditionAnd continuously monitor its performance parameters. This is the most rigorous and reflective experiment of real usage scenarios.

3、 Main experimental conditions (key parameters)

This is aComprehensive stress testThe conditions are composed of three parameters: temperature, humidity, and altitude (air pressure). The specific severity level (parameter value) needs to be tailored according to the expected usage environment of the equipment, but the standard provides a typical range of conditions.

Typical test profile example (working test):

1. Initial detectionInspect the appearance and functionality of the equipment under standard atmospheric conditions.

2. cooling phaseReduce the temperature inside the test chamber to the specified levellow temperatureConditions (such as -55 ° C, -40 ° C, or depending on specific equipment requirements).

3. Low temperature stabilityMaintain low temperature for a period of time to stabilize the overall temperature of the equipment.

4. Voltage reduction stageWhile maintaining low temperature, reduce the air pressure inside the test chamber to the specified levellow pressure(Corresponding to a certain height, such as 10000m, 15000m or higher).

• For example, the standard air pressure at a height of 15000m is approximately 12.0 kPa.

5. Comprehensive stress maintenance stage (core steps)：

• InLow temperature, low pressureUnder certain conditions, the equipmentStart workAnd conduct performance measurements.

• Then, while maintaining low air pressure, raise the temperature to the specified levelhigh temperature and high humidityConditions (such as 30 ° C, 95% RH or 40 ° C, 95% RH). This stage is to simulate the equipment entering a warm and humid air mass from a cold high altitude, or the temperature difference between day and night.

• InHigh temperature, high humidity, low air pressureUnder certain conditions, the equipmentContinue workingAnd conduct performance measurements.

• AttentionThis stage is the focus of assessment, as temperature changes and low air pressure can exacerbate the risk of moisture infiltration and condensation.

6. recoverRestore the test chamber to standard atmospheric conditions (temperature, humidity, air pressure).

7. Final testingConduct a comprehensive visual and functional inspection of the device again, and compare it with the initial data.

Key parameter range:

• temperatureLow temperature is usually-55 ° C to -25 ° CHigh temperature is usually+30 ° C to+40 ° C.

• relative humidityThe relative humidity during the high temperature stage is usually95%.

• Height (air pressure)Usually:3000m to 25000m(Corresponding to an air pressure of approximately 70.1 kPa to 2.5 kPa). The specific height is determined based on the equipment installation platform (such as inside the transport cabin, outside the fighter jet, for high-altitude use, etc.).

4、 Experimental equipment and facilities

The experiment must be conductedThree comprehensive test chamberIn progress, the device needs to have:

• Temperature control capabilityCan achieve rapid heating and cooling.

• Humidity control capabilityCan accurately control high humidity during high temperature stages.

• Pressure/altitude simulation capabilityCapable of vacuuming and simulating low-pressure environments.

• integrated controlCan accurately control temperature, humidity, and air pressure to change according to predetermined programs.

5、 Failure mechanism and assessment focus

This experiment mainly exposes the following issues:

• The respiratory effectDue to temperature cycling and pressure changes, air inside the equipment casing may be drawn in and expelled, potentially bringing external moisture into the interior and causingInternal condensationCausing short circuits and electrochemical corrosion.

• Low-pressure effect：

• The decrease in air dielectric strength can easily lead toHigh voltage arc and corona discharge.

• Difficulty in heat dissipation may lead toComponent overheating.

• Sealing components due to internal and external pressure differenceleak.

• Low temperature effectMaterial brittleness, lubricant solidification, and decreased battery performance.

• Damp heat effectDecreased insulation resistance, metal corrosion, and material expansion.

6、 Result evaluation and qualification criteria

After the experiment is completed, the equipment should meet the following requirements:

• structural soundnessNo deformation, cracks, leaks, or other mechanical damage.

• Functioning normally：

• During the experiment, all functions were normal and the performance parameters were within the specified tolerance range.

• After the experiment, the equipment's functional performance still meets the technical requirements.