How to effectively reduce the leakage rate of the vacuum system
Time：2020-09-18 09:41 Click：
The structure of the vacuum system of the vacuum furnace is the key to affecting the tightness of the vacuum system and the leakage rate of the system. Whether the structure of the vacuum system is reasonable or not will directly affect the tightness of the system and the leakage rate of the system. How to effectively reduce the leakage rate of the vacuum system? The practice of Kejia electric furnace is to start with the furnace body design, sealing type, sealing material, sealing structure, etc. to make the vacuum furnace achieve a higher vacuum furnace and a smaller air leakage rate.
The improvements made by Kejia electric furnace in furnace body design are:
The first is to avoid blind spots with a small radius of curvature as much as possible. Secondly, the evacuated pipes, air supply pipes and other pipes connected to the vacuum chamber all use arc transition to make the air path unimpeded. The structure of various connecting parts in the vacuum chamber is precisely designed to make the air path unblocked and avoid blockage of the air path. The brighter the surface, the less likely it is to absorb gas. In order to obtain a better vacuum, the inner surface of the vacuum system is polished.
The choice of seal type is:
Kejia's vacuum furnace sealing type can be selected according to the level of vacuum required by the user and actual work needs. For artificial crystal growth equipment, the general required vacuum is below 10-3Pa, so there is no need to use metal sealing. Take the TDR-70 single crystal furnace as an example. We choose magnetic fluid seal as the rotary dynamic seal, select high-precision and large expansion and contract welding bellows for mobile sealing, and use "O" seals or "O" seals for small diameter shafts. For Wilson seals, various static seals use "0" type seals, with a diameter compression ratio of 25%.
Selection of seal material:
For vacuum systems with a vacuum degree below lO-3Pa, rubber sealing rings are generally selected to meet the requirements. However, taking into account the needs of actual working conditions (the temperature in the vacuum chamber can reach up to 2300oC, after the sealing part is water-cooled, the temperature is about 80oC, and the temperature in some places can reach 100oC or more). Therefore, it is necessary to choose an ideal sealing ring material. Used for vacuum sealing rubber materials, in addition to having a smooth surface, no scratches, and no cracks, it also needs to have low permeability and outgassing rate, good heat resistance and oil resistance, and at the same time have a certain strength, hardness and elasticity Wait.
Choice of sealing structure:
In various vacuum systems, more than 80% of the seals are static seals. The quality of the static seal has a great influence on the vacuum degree and air leakage rate of the system. Therefore, Kejia's equipment static sealing structure is carefully designed to achieve the desired effect. For the design of static seal structure, it is important to consider how to select key sealing surfaces, how to reduce residual gas, and how to give full play to the functions of rubber sealing rings. For more questions, please contact us directly or leave a message. We will contact you as soon as possible.