(1) Because the main valve seat seal material is PTFE, it is inert to almost all chemicals, and has a small coefficient of friction, stable performance, not easy to aging, wide temperature range and excellent sealing performance of the comprehensive characteristics.
However, the physical properties of PTFE, including high coefficient of expansion, sensitivity to cold flow and poor thermal conductivity, requires that the design of the valve seat seal must be centered on these characteristics. Therefore, when the sealing material hardens, the reliability of the seal is undermined.
Furthermore, PTFE has a low temperature rating and can only be used at temperatures less than 180 °C. Beyond this temperature, the sealing material becomes unstable. Above this temperature, the sealing material will deteriorate. Considering the long-term use of the case, generally only used at 120 ℃.
(2) Its regulating performance relative to the globe valve is a little worse, especially pneumatic valves (or electric valves).