What Problems Will Affect Valve Sealing?

Industrial valves require good sealing ability, and usually some special sealing designs are made to achieve this goal. However, in the actual application of valves, there are still many factors that affect the sealing effect of the valve, which are related to the valve itself and the contact medium.

1. Sealing pair structure

Under the change of temperature or sealing force, the structure of the sealing pair will change. These changes will affect and change the interaction force between the sealing pairs, thereby reducing the sealing performance of the valve. Therefore, when selecting seals, it is necessary to select seals with elastic deformation. At the same time, it is also necessary to pay attention to the width of the sealing surface. The reason is that the contact surface of the sealing pair cannot be completely consistent. When the width of the sealing surface increases, it is necessary to increase the interaction force required for the seal.

2. Sealing surface specific pressure

The specific pressure of the sealing surface affects the valve sealing performance and the service life of the valve. Under the same conditions, too large a specific pressure will cause damage to the valve, but too small a specific pressure will cause valve leakage. Therefore, it is necessary to fully consider the suitability of the specific pressure during design.

3. Physical properties of the medium

The physical properties of the medium also affect the sealing performance of the valve. These physical properties include temperature, viscosity and surface water absorption. Temperature changes not only affect the relaxation of the sealing pair and the change of part size, but also have an inseparable relationship with the viscosity of the gas. The viscosity of the gas increases or decreases with the increase or decrease of the temperature.

In order to reduce the degree of damage to the sealing performance of the valve by the temperature, we should design the sealing pair into a valve with thermal compensation such as an elastic valve seat when designing the sealing pair. Viscosity is related to the permeability of the fluid. When under the same conditions, the greater the viscosity, the smaller the permeability of the fluid. The surface water absorption refers to the removal of a thin film on the metal surface. Because of this thin oil film, the surface water absorption will be destroyed, resulting in blockage of the fluid channel.

4. The quality of the sealing pair

The quality of the sealing pair mainly refers to the selection, matching and manufacturing accuracy of the materials. For example, the valve disc and the valve seat sealing surface are very consistent, which can improve the sealing performance. The characteristic of more circumferential corrugations is that its labyrinth sealing performance is good. Valve leakage is very common in life and production. It may cause waste or bring danger to life, such as leakage of tap water valves. It may lead to serious consequences, such as leakage of toxic, harmful, flammable, explosive and corrosive media in the chemical industry, which seriously threatens personal safety, property safety and environmental pollution.