There are many factors affecting the valve seal, mainly the following:
Sealed secondary structure
The structure of the seal pair changes under the influence of temperature or sealing force. Moreover, this change affects and changes the force between the seal pairs, thereby reducing the performance of the valve(such as ball valve) seal.
Therefore, when selecting a seal, it is necessary to select a seal with elastic deformation. Also, pay attention to the width of the sealing surface. The reason is that the contact surface of the sealing pair cannot be completely matched. When the width of the sealing surface is increased, the force required for sealing is increased.
Sealing surface pressure
The specific pressure of the sealing surface affects the sealing performance of the valve and the service life of the valve. Therefore, the sealing surface specific pressure is also a very important factor. Under the same conditions, the specific pressure will cause damage to the valve, but the pressure will be too small to cause the valve to leak. Therefore, we need to fully consider the appropriateness of the specific pressure in the design.
Physical properties of the medium
The physical properties of the media also affect valve(such as butterfly valve) sealing performance. These physical properties include temperature, viscosity, and hydrophilicity of the surface. Temperature changes not only affect the slack of the seal pair and the dimensional change of the part, but also have an inseparable relationship with the viscosity of the gas. The viscosity of the gas increases or decreases as the temperature increases or decreases.
Therefore, in order to reduce the degree of influence of temperature on the sealing performance of the valve, we design it as a thermally compensated valve such as an elastic valve seat when designing the sealing pair. Viscosity is related to the ability of the fluid to penetrate.
When under the same conditions, the greater the viscosity, the smaller the ability of the fluid to penetrate. The hydrophilicity of the surface means that the film is removed when there is a film on the metal surface. Because of this very thin oil film, it will damage the hydrophilicity of the surface, leading to the passage of fluids.
Quality of the seal pair
The quality of the seal pair mainly means that we have to check the selection, matching and manufacturing precision of the materials. For example, the valve flap fits well with the seat sealing surface to improve sealing. The characteristic of the circumferential waviness is that the labyrinth sealing performance is good.
Valve leakage is very common in life and production. It can cause waste or bring danger to life. For example, the leakage of tap water gate valve can lead to serious consequences, such as toxic, harmful, flammable and explosive in the chemical industry. Corrosive dielectric leakage, etc., seriously threaten personal safety, property safety and environmental pollution accidents.
A valve that relies on external force rotary drive to open and close is designed with a sealing device that uses a certain number of packing seals in the packing culvert to achieve the sealing effect, but what about the sealing situation?
Leakage at the packing of the valve is one of the most prone to leakage faults in the valve, but there are two reasons for this.