Low Atmospheric Pressure Environmental
The air has a certain weight to form atmospheric pressure due to the gravitational force of the earth. As the height increases, the air gradually becomes thinner and the atmospheric pressure gradually decreases. According to the actual measurement, within 3000km of sea level, the air pressure is reduced by 100Pa for every 10 meters of height. The atmospheric pressure at approximately 31 km is 1/100 of the sea level standard atmospheric pressure value.
In addition to height, atmospheric pressure is also related to weather changes. At the same point, the sunny air pressure is high cloudy air pressure. In addition, the winter pressure is higher than the summer pressure.
What is Altitude Simulation Test ?
The altitude simulation test is to put the test sample into the altitude test chamber, and then reduce the air pressure in the altitude test chamber to the value specified by the relevant standards and maintain the test for the specified duration. Its main purposes are aviation, aerospace, information, electronics and other fields, to determine the environmental adaptability and reliability test of instrumentation, electrical products, materials, parts and equipment under low pressure, high temperature and low temperature single or simultaneous action.
ow A h essure E vironmental
The impact of low atmospheric pressure environmental on products is multifaceted. These include the following:
- The direct mechanical effect of a pressure difference caused by a decrease in air pressure.
- The effect of reduced air density on heat dissipation and thrust of power equipment and electrical performance of electrical equipment.
- The pressure difference leads to additional effects after seal damage and harmful effects on volatile materials.
(1) Direct Destruction of Shelled Sealing Products
Under the action of low pressure, the shell-sealed sealing product directly causes the shell to be damaged due to excessive pressure difference between the inside and the outside. In addition, the presence of a pressure differential also results in seal damage.
(2) Reduce Electrical Performance
Air is a good insulating medium under normal atmospheric conditions. Many electrical products use air as an insulating medium. When these products are used in high-altitude areas or as airborne equipment, partial discharges are often generated near electrodes with stronger electric field strength due to lower atmospheric pressure. More seriously, air gap breakdown sometimes occurs. This means that the normal operation of the device is destroyed. Therefore, the low pressure environment will also have an impact on the electrical performance of electrical and electronic products. Especially in the case of air as an insulating medium, the effect of low air pressure is more significant.
(3) Heat Dissipation Products Warming
The so-called heat-dissipating product refers to a test sample in which the difference between the temperature of the hottest surface and the ambient temperature is greater than 5 °C after the temperature of the test sample is stabilized under air conditions and the specified atmospheric pressure.
Most electrical and electronic products are heat dissipation products such as motors, transformers, etc. These products consume a portion of the electrical energy in use, causing them to become thermal energy, and the temperature of the product increases. The temperature of the heat dissipation product increases as the height of the poster increases (atmospheric pressure decreases). The temperature rise is roughly linear with the altitude, and its slope is determined by its own structure, heat dissipation, and ambient temperature.
(4) Lead to the Loss of Contagious Substances
A decrease in pressure causes a decrease in the boiling point of the liquid. For liquids with a high saturated vapor pressure at normal atmospheric conditions at sea level, the low pressure causes it to evaporate and even boil.
- Leaking gas or liquid inside the sealed casing;
- The sealed container is deformed, broken or exploded;
- The physical and chemical properties of low-density materials change;
- Arc or corona discharge at low pressure causes equipment malfunction or malfunction;
- Reduced heat transfer efficiency at low pressure causes the equipment to overheat;
- Lubricating oil volatilization;
- Engine starting and combustion are unstable and thrust or traction is reduced;
- Hermetic seal failure, etc.