Effect Of Low Pressure Environment On Equipment

The impact of low pressure environment on equipment is multidimensional, including the direct mechanical impact of pressure difference caused by reduced pressure, the impact of reduced air density on heat dissipation and power equipment thrust and the impact of electrical equipment electrical performance, the additional impact of pressure difference caused by seal damage and harmful effects on volatile substances.

(1) Direct destruction of sealing products with shells

Under the action of low pressure, the internal, and external pressure difference will directly lead to the damage to the shell, and the existence of pressure difference will also lead to the damage to the seal.

(2) Resulting in a large temperature rise of heat dissipation products

The so-called heat dissipation product refers to the test sample with a difference of more than 5 °C between the surface hot spot temperature and the ambient temperature after the test sample temperature reaches stability under free air conditions (when there is no forced air circulation) and the specified atmospheric pressure (86 KP).

(3) Damage the sealing product

The pressure difference between the inside and outside of the seal product causes a force from high pressure to low pressure, and the shell of the seal product will bear this force. Generally, most products are produced and sealed in plain areas, and the pressure inside the product is generally balanced with the local atmospheric pressure when sealed. When the product is used at a high altitude or altitude, due to the reduction of atmospheric pressure around the product, the product shell and seal body will be subjected to a force directed towards the shell, which can deform the shell and damage the seal, resulting in product failure. Sometimes the seal is broken resulting in moisture into the product cavity, so that the product is damaged due to moisture.

(4) Lead to the loss of volatile substances

The decrease in pressure will lower the boiling point of the liquid, and for liquids that have a high saturated vapor pressure under normal atmospheric conditions at sea level, the low pressure will cause them to evaporate or even boil.

Lubricating oil or grease falls into the above category. The molecules in the liquid will escape the surface of the liquid and enter the surrounding air after gaining a certain amount of energy. These molecules will collide with air molecules in the atmosphere, and some will crash back into the liquid surface and become bound. This evaporation process is an equilibrium process. When the atmospheric pressure decreases, the air density decreases, the probability of liquid volatilization molecules entering the air is reduced, and the likelihood of being knocked back to the liquid surface is also greatly reduced. Therefore, under the condition of low pressure, the speed of liquid volatilization will be greatly increased. The reduction of pressure will accelerate the volatilization of lubricating oil (or grease), resulting in increased friction of moving parts and accelerated abrasion of the surface of moving parts.

Plasticizers in organic materials will also accelerate volatilization due to reduced air pressure. The volatilization of the plasticizer causes the aging of the organic material and changes its mechanical or electrical properties.

Volatile can also contaminate products and surrounding objects, resulting in contamination or even corrosion of products or objects.

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