The ball valve's most crucial element for ensuring a proper seal is the valve seat sealing ring, which is typically made of PTFE. PTFE possesses exceptional qualities that make it an ideal choice for this application. One of its key advantages is its inertness to nearly all chemical substances. Additionally, PTFE exhibits a low friction coefficient, ensuring smooth operation and stable performance. It is also resistant to aging and can withstand a wide range of temperatures, contributing to its excellent sealing capabilities.
However, it is important to consider the physical properties of PTFE when designing the seat seal. PTFE has a high coefficient of expansion and is susceptible to cold flow, which necessitates careful consideration during the design process. Furthermore, PTFE has poor thermal conductivity, which can affect the overall performance of the sealing system.
It is worth noting that the reliability of the sealing can be compromised when the sealing material hardens over time. This emphasizes the importance of regular maintenance and timely replacement of worn-out parts. Additionally, PTFE has limitations in terms of temperature resistance. It can only be effectively used up to 180°C, as beyond this temperature, the material begins to degrade. In practical applications, it is recommended to use PTFE at temperatures below 120°C for long-term usage.
In conclusion, the selection and design of the seat seal in ball valves must take into account the unique properties of PTFE. Despite its limitations, when properly utilized within its temperature range and coupled with appropriate maintenance practices, PTFE can provide reliable and efficient sealing performance.
The globe valve outperforms the butterfly valve in terms of adjustment performance, especially in comparison to pneumatic or electric valve designs. This means that the butterfly valve may not be as precise in regulating flow or pressure as other types of valves.