How is the sealing performance of Ball Valves?

1. Importance of sealing performance
Ball Valves are mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. Therefore, the quality of their sealing performance is directly related to whether the valve can effectively prevent the leakage of the medium, thereby ensuring the safe operation of the pipeline.
2. Main evaluation indicators of sealing performance
Leakage: Evaluate the leakage of the ball valve according to the test results. Generally, the leakage level of the ball valve is divided into zero leakage, slight leakage, visible leakage and severe leakage. Zero leakage is the ideal state, indicating that the valve is completely leak-free in the closed state.
Sealing pressure: The maximum medium pressure that the ball valve can withstand in the closed state. The higher the sealing pressure, the better the sealing performance of the valve.
Sealing time: The ability of the valve to maintain a sealed state under a specific pressure and time. The longer the sealing time, the higher the durability and reliability of the valve.
3. Key factors affecting sealing performance
Quality of the sealing pair: The sealing pair includes the ball and the valve seat, and its quality directly affects the sealing performance. The roundness of the ball and the roughness of the valve seat sealing surface are key factors. The roundness of the ball is usually required to be level 9, and the roughness of the sealing surface should meet the relevant standards.
Specific pressure on the sealing surface: Specific pressure refers to the pressure acting on the unit area of ​​the sealing surface. The size of the specific pressure directly affects the sealing, reliability and service life of the ball valve. Under the same other conditions, the leakage is proportional to the square of the pressure difference.
Physical properties of the fluid: including viscosity, temperature, hydrophilicity, etc. The greater the viscosity of the fluid, the smaller its permeability, which is conducive to sealing. Temperature and hydrophilicity may affect the performance of the sealing material.
4. Measures to improve sealing performance
Select high-quality sealing materials to ensure that the roundness and roughness of the ball and valve seat meet the requirements.
Appropriately increase the specific pressure on the sealing surface to improve the sealing performance. However, it should be noted that excessive specific pressure will increase the operating torque and wear of the valve.
Select appropriate sealing materials and structures according to the physical properties of the medium to improve the sealing performance and service life of the valve.