The sealing material of valve seat is generally polytetrafluoroethylene. Among the existing plastics, polytetrafluoroethylene has the strongest chemical stability. Its chemical stability is even more stable than that of precious metal gold and platinum, glass, ceramics, enamel, special steel and alloy. The substances with strong chemical corrosiveness - concentrated acid, dilute acid, concentrated lye, and the strongest oxidant can not have any effect on PTFE; It is called. Except that some halogenated amines or aromatic hydrocarbons cause slight swelling of polytetrafluoroethylene plastics, ketones, acids, cools and other organic solvents have no effect on polytetrafluoroethylene, and will not cause weight change and swelling. Only molten alkali metals, chlorine trifluoride and elemental fluorine can act on it, but only under high temperature and pressure. In addition, polytetrafluoroethylene is not affected by oxygen or ultraviolet rays, does not absorb water, and is incombustible. It has high heat resistance and cold resistance. The temperature range of use is - 180~250 ℃. After being treated at 250 ℃ for 240 hours, the mechanical properties do not decrease, and the weight loss per hour at 390 ℃ is 0.006%. Its dielectric properties are excellent, and its electrical properties are not affected by frequency and temperature. It can work at 250 ℃ for a long time. It can be seen from the above that it is ideal to use PTFE as the seal of pneumatic ball valve. The elastic modulus of polytetrafluoroethylene is very large. Therefore, the performance of the material determines that its elastic deformation is very small. Once it is used for a long time, the elasticity of the material is not enough to make up for the wear of the sealing surface. At this time, the seal of the pneumatic ball valve will be damaged. Therefore, when designing the valve seat, we consider how to increase its elasticity from the structure, and we choose the elastic structure.

The d371x butterfly valve standard d371 butterfly valve is actually a midline wafer butterfly valve, and its common models are d371X-6, d371X-10, d371x-10p, d371x-10c, d371X-10x, d371X-16, d371x-16c, d371x-16q. Therefore, the standards for the above valve codes are the same, that is, the d371x butterfly valve standard is adopted