For rubber seals to ensure smooth baking and degassing

Heat resistance In a vacuum system, it is often necessary to degas the system or components, which is often done by baking. This requires a certain heat resistance to the rubber seal to ensure the smooth progress of baking and degassing. Generally, the baking temperature is below 120 ° C and the vacuum of 10-5 Pa, butyl or nitrile rubber can be used; if higher baking temperature is required and it is required to work in ultra-high vacuum environment, fluorine is required. rubber.

Compression Deformation In a vacuum system, a large number of vacuum seals are operated under compression. In order to make the seal have the reliability of sealing and ensure a certain sealing life, the vacuum sealing rubber should have a small compression deformation value (finally less than 35%), and at the same time require a relatively slow compressive stress relaxation speed (ie, compressive stress relaxation) The coefficient is large) to ensure a high working life of the vacuum seal.

Dingqing rubber has low permeability to non-polar gases and is also caused by the presence of a clear group of polar groups. Therefore, the higher the acrylonitrile content of the nitrile rubber, the lower the gas permeability. Temperature has a great influence on the gas permeability of rubber. The higher the temperature, the greater the gas permeability. In addition, the gas permeability of different gases in different rubbers is also different.