What are the main factors affecting valve sealing?
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This post was last edited by kn on 2020-6-11 12:51. Valve leakage is very common in both daily life and industrial production, and it has a significant impact. Otherwise, it can lead to waste or pose a danger to lives, such as leaks in tap water valves, as well as serious consequences in industries like the chemical industry. Accidents such as leaks of toxic, harmful, flammable, explosive, and corrosive substances pose a serious threat to human safety, property safety, and environmental pollution. A valve that is opened and closed through external rotational force has been designed, and it is equipped with a sealing device intended to install a certain number of packing rings in the packing box in order to achieve sealing; but how effective is this sealing? What’s the situation? Leakage at the valve packing is one of the most common causes of leakage problems in valves, but the main reasons are as follows. 1. Seal pair structure: Under the influence of changes in temperature or sealing force, the structure of the seal pair changes. Moreover, this change affects and alters the force between the sealing surfaces, thereby reducing the sealing performance of the valve. Therefore, when selecting a seal, it is essential to choose one that can undergo elastic deformation. At the same time, attention should also be paid to the width of the sealing surface. The reason is that the contact surfaces of the sealing pair cannot fit together perfectly; as the width of the sealing surfaces increases, more force is required to achieve sealing. 2. Specific pressure on the sealing surface: The level of specific pressure on the sealing surface affects both the sealing performance of the valve and its service life. Therefore, the specific pressure on the sealing surface is also a very important factor. Under the same conditions, an excessively high specific pressure can cause damage to the valve, while an excessively low specific pressure can lead to valve leakage. Therefore, it is necessary for us to fully consider the appropriateness of the specific pressure during the design process.
The last edit to this post was made by kn on 2020-6-11 at 12:53. 3. Physical properties of the medium: The physical properties of the medium also affect the sealing performance of valves. These physical properties include temperature, viscosity, and surface hydrophilicity. Temperature changes not only affect the relaxation of the sealing pair and the variation in component dimensions, but are also closely related to the viscosity of the gas. Gas viscosity increases or decreases as the temperature rises or falls. Therefore, in order to reduce the impact of temperature on the sealing performance of valves, we design the sealing pairs as valves with thermal compensation features, such as elastic valve seats. Viscosity is related to the fluid’s ability to penetrate. Under the same conditions, the greater the viscosity, the lower the fluid’s permeability. Surface hydrophilicity refers to the need to remove a thin film from the metal surface. Because this thin layer of oil film destroys the surface’s hydrophilicity, causing blockages in the fluid channels.