What is a Temperature and Low Air Pressure Test Chamber?

Temperature and Low Air Pressure Test Chambers are primarily used in aerospace, electronics, defense, and other industrial sectors to determine the reliability of electrical and electronic products, including components, materials, and instruments. They conduct storage and transportation reliability tests under single or simultaneous conditions within the chamber, and simultaneously test the electrical performance parameters of the test specimens while they are powered on.

Current Status of Industry Technology Development: With the rapid development of high-end manufacturing industries such as semiconductors, new energy, and aerospace, the importance of environmental reliability testing equipment in product quality control is increasingly prominent. As a core device for simulating extreme temperature environments, the technical level of walk-in rapid temperature change test chambers directly affects the product's R&D progress and quality reliability. Currently, environmental testing equipment has achieved significant breakthroughs in key indicators such as temperature control accuracy, temperature change rate, and uniformity, gradually breaking the technological monopoly.

In terms of technological evolution, modern temperature change test chambers have evolved from a single temperature testing function into a comprehensive testing platform integrating rapid temperature change, temperature shock, low air pressure simulation, and humidity control. The semiconductor industry, in particular, has more stringent requirements for testing equipment, demanding higher temperature change rates, more precise temperature control, and more stable performance.

Working Principle

1. Physical Principles of Altitude and Air Pressure Changes

Air pressure refers to the pressure exerted by air on the ground and surrounding objects. Normally, air pressure at standard atmospheric pressure is 101.3 kPa. However, atmospheric pressure gradually decreases with increasing altitude. This phenomenon is mainly due to the thickness of the air layer around the Earth and the effect of gravity. In high-altitude areas, such as plateaus, mountains, or during high-altitude flight, air pressure becomes thinner, and the oxygen content in the air decreases, resulting in different environmental pressures for people and equipment compared to flat terrain.

These air pressure changes can have multifaceted effects on products. For example, electronic devices may experience reduced heat dissipation due to decreased oxygen content, and the durability and lifespan of automotive components may be weakened by the low-pressure environment at high altitudes. The purpose of a low-pressure test chamber is to reproduce these environments in the laboratory, simulating air pressure conditions at different altitudes to test product performance under extreme conditions.

2. Core Working Principle of Low-Pressure Test Chambers

The working principle of low-pressure test chambers is based on the physical law that atmospheric pressure decreases with increasing altitude. The equipment simulates different altitudes by evacuating air through a vacuum system or changing the air pressure inside the chamber using a compressor. Components such as the vacuum pump and vacuum valves inside the test chamber effectively regulate the air pressure to achieve a preset low-pressure environment.

In addition to air pressure control, low-pressure test chambers typically also have temperature and humidity adjustment functions to simulate more complex environmental conditions. For example, in high-altitude areas, temperatures are usually low, and humidity may vary significantly. Therefore, low-pressure test chambers are equipped with temperature and humidity control systems to ensure the comprehensiveness of the testing environment.

According to Part 2 of GB/T 2423.21-2008 Environmental Testing Standard for Electrical and Electronic Products, namely "Low-Pressure Test Methods," low-pressure test chambers can accurately simulate environmental changes under different air pressure conditions. This standard is widely used in quality control and durability testing of electrical, electronic, and aerospace products.

Impact on Product Performance

When using a high/low temperature and low pressure test chamber, the low pressure set inside the chamber has three main impacts on product performance:

1. The temperature of heat-dissipating products increases as atmospheric pressure decreases.

Many electrical and electronic products are heat-generating, such as contactors, motors, transformers, and resistors. During use, some of the electrical energy in these products is converted into heat, causing the product to heat up. The temperature rises as atmospheric pressure decreases and as altitude increases, leading to instability or performance degradation in electronic devices.

2. Low pressure affects product sealing.

Due to the pressure difference caused by atmospheric pressure changes, a force is created from high pressure to low pressure. Under this force, gas flow reaches equilibrium. For sealed products, the outer casing will bear this force. This force can cause the casing to deform, the seal to rupture, and product failure.

3. The impact of low pressure on electrical performance.

The electrical performance of electrical and electronic products is affected by altitude and air pressure, especially air as an insulating medium; low pressure has a greater impact on electrical equipment. In the atmospheric environment, air serves as a good insulating medium, and many electrical products use air as their insulating medium. When applied to high-altitude operations or motor equipment, due to the decrease in atmospheric pressure, partial discharge often occurs near strong electrodes. In severe cases, this can cause the air gap to break down, disrupting the normal operation of the equipment.

Maintenance and Care

1. High and low temperature test chambers are generally located at relatively high temperatures. We recommend placing them in a relatively benign temperature environment, with our experienced range being 8℃~23℃. For laboratories lacking this capability, appropriate air conditioners or cooling towers must be provided.

2. Maintain dedicated personnel for professional management. Units with the resources should periodically send personnel to the supplier's factory for training to acquire professional maintenance and repair experience and capabilities.

3. Clean the condenser every 3 months. For air-cooled compressors, regularly inspect the condenser fan and clean the condenser to ensure good ventilation and heat exchange performance. For water-cooled compressors, in addition to ensuring the inlet water pressure and temperature, the appropriate flow rate must also be maintained, and the condenser interior must be cleaned and descaled regularly to maintain its continuous heat exchange performance.

4. Clean the evaporator regularly. Due to varying cleanliness levels of the samples, a lot of dust and other small particles will accumulate on the evaporator under forced air circulation; therefore, it should be cleaned regularly.

5. Clean and balance the circulating fan and condenser fan; similar to cleaning the evaporator, due to the varying working environments of the test chamber, dust and other small particles will accumulate on the circulating fan and condenser fan, requiring regular cleaning.

6. Clean the water system and humidifier; clogged water systems or scale buildup in the humidifier can lead to dry burning and potential damage, so regular cleaning of the water system and humidifier is essential.

7. After each test, set the temperature to near ambient temperature, operate for approximately 30 minutes, then disconnect the power and wipe the interior walls clean.

8. If equipment relocation is necessary, it is best to do so under the guidance of technical personnel or the manufacturer to avoid unnecessary damage.

9. When the equipment is not in use for extended periods, power it on every two weeks for at least one hour.

Application Value

Low-pressure test chambers are widely used in electronics, electrical appliances, automotive parts, aerospace equipment, and other fields. By simulating high-altitude, low-pressure environments, this equipment helps companies identify potential problems with their products under extreme conditions, improving product quality and reliability.

For example, in aerospace equipment testing, low-pressure test chambers can simulate the high-altitude environment of aircraft flight, verifying the performance of equipment under extreme pressure conditions. For automotive manufacturers, low-pressure test chambers help ensure the reliability of automotive components in high-altitude regions. Furthermore, the operational stability, durability, and pressure resistance of electronic products in high-altitude areas can also be comprehensively tested using low-pressure test chambers.

Temperature and low-pressure test chambers, as key equipment for ensuring product quality and reliability, play an irreplaceable role in many industries. With their precise environmental simulation capabilities, they help companies anticipate product performance under extreme conditions, providing a solid basis for product optimization and upgrades. As industries continue to raise their product quality requirements, low-pressure test chambers will continue to innovate and develop, contributing more to industry progress and product quality assurance with more advanced technologies and more comprehensive functions, becoming an indispensable "quality guardian" for many companies.