The so-called vacuum system refers to a device which can meet the requirements of certain vacuum degree by combining vacuum pump, vacuum gauge and various parts through pipes in a proper way. The basic requirements of vacuum system are:
① Obtain the required limiting vacuum and working vacuum in the device or working room. The limiting vacuum degree refers to the degree of vacuum achieved by the device when there is no leakage and deflation. The second working vacuum degree refers to the degree of vacuum that can be maintained when the device is vacuum treated. A large amount of gas is often released during vacuum treatment, and the working vacuum will be significantly lower than the limit vacuum. Limit vacuum degree and working vacuum degree have their own importance, they affect the quality of devices from different sides.
② The time required to obtain a certain working vacuum. This time depends on the pumping speed of the vacuum system. This time can be shortened by increasing the pumping speed. Large studios, such as aerospace simulation devices, obviously need large pumping speed. Sometimes, although the studio is not large, due to the serious leakage, the vacuum system also needs a large pumping speed, otherwise a large number of leakage will greatly reduce the vacuum degree, making the system unable to work.
③ There are suitable residual gas components in the device or working room. It has been proved that it is not enough to simply improve and guarantee the limiting vacuum and working vacuum, and there should be some requirements for the residual gas composition.
④ In order to meet these requirements, it is necessary to comprehensively consider the selection of vacuum pumps, the determination and arrangement of pipe size, assembly process, etc.
Generally speaking, for a vacuum system with better air tightness, if there is no regular air release and no steam source inside, a smaller vacuum pump with better ultimate vacuum degree can be used.
However, if there is a lot of air leakage in the system, the method of increasing the pumping speed must be used to ensure its working vacuum degree. At this time, the vacuum pump with larger pumping speed should be used, and the pipeline flow guide should be increased as much as possible, that is, the short and thick pipeline should be selected.
The residual gas composition of vacuum system, if there is no other gas source in the system, mainly depends on the characteristics of the vacuum pump.