The sealing performance of a #valve refers to its ability to prevent leakage of the medium through its various sealing components. This is the most important technical performance indicator of a valve. Medium leakage can lead to material loss, environmental pollution, and, in severe cases, accidents. For flammable, explosive, toxic, or radioactive media, leakage is even more unacceptable. Therefore, valves must have reliable sealing performance.
A.Static sealing refers to the formation of a seal between two stationary surfaces;
Examples of static seals include:
- Gaskets: Thin pieces of material are placed between two surfaces to enhance the sealing.
- O-rings: Circular rings typically made of elastomer used in grooves to provide a seal.
- Metal seals: Used in high-temperature and high-pressure applications, often made from soft metals.
B. Dynamic sealing is the method used to prevent the medium inside a valve from leaking along the valve stem during movement；
- Globe Valves: Globe valves often use stuffing boxes with packing material to seal around the moving stem, preventing leaks as the stem moves up and down to open or close the valve.
- Gate Valves: gate valves typically employ packing glands filled with packing material (such as graphite or PTFE) to seal around the valve stem, ensuring no leakage when the stem moves to lift or lower the gate.
- Ball Valves: Ball valves use dynamic stem seals, often O-rings or V-ring packing, to prevent leaks around the rotating stem as the ball rotates to open or close the valve.
- Butterfly Valves: Butterfly valves often have stem packing or O-rings around the stem to prevent leaks as the stem rotates the disc to control flow.
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