In the application of the vacuum system, the extracted gas is not only included in the various gases produced in the application process, but also the original air air in the system.
1. The gas produced in the process of vacuum system
It includes gases released by the material in the process and the gas introduced by the process. Meanwhile, the liquid or solid vaporized gas in the vacuum system is also included. The amount of gas in different processes and different treated materials is different.
2. The original atmospheric gas in the vacuum system
In vacuum system, vacuum vessel chamber, vacuum pipeline and so on, these originally contain a certain amount of atmospheric gas composition, in the early stage of pumping, they are the main gas load of vacuum system gas pumping, and are also the earliest pumping out of the system.
3. Leakage of gas in a vacuum system
The leaking gas includes the atmosphere that leaks into the vacuum system through the vacuum sealed connections and various leaky channels. For a defined vacuum system, the amount of gas leaked is a constant. The application of different vacuum systems and different limit pressures also have strict limits on the amount of leakage gas.
4. The gases released from the surface of various materials in the vacuum system.
At atmospheric pressure, the surface of the material in the vacuum system adsorbs and dissolves some gases. Under negative pressure, this part of the gas will be released again. Its discharge rate is related to material properties, processing technology and surface state of materials.
5, the air outside the vacuum system penetrates through the wall material into the system.
The gas will also dissolve and permeate in the solid. Therefore, the atmosphere will permeate some gases into the vacuum system through the structural material of the container wall. This kind of penetration can not be considered under the general metal system, but some applications in the glass vacuum system or thin wall metal system need to consider the influence of the permeable gas.
The above 5 aspects constitute the total pumping load of the vacuum system.