What are the main factors affecting valve seal?

Valve leakage is common in life and industrial production, and the impact of the very large, light can cause waste, or bring danger to life, such as tap water valve leak, or causing serious consequences, such as chemical industry of poisonous and harmful, inflammable, explosive and corrosive medium leakage in the nature of, serious threat to personal safety and property safety, and environmental pollution accidents.A valve that depends on external force to rotate transmission to open and close, design has a sealing device, use in packing cullet to install a certain number of packing sealing ring already, achieve sealing effect, but how does the sealing situation have?Valve packing leakage, is the most prone to leakage fault in the valve one of the parts, but the cause of the following aspects of the cause.

1. Sealing structure
Under the action of temperature or sealing force, the structure of the sealing pair will change.And this change will affect and change the pressure between the sealing pair, thereby reducing the performance of valve sealing.Therefore, in the selection of seals, must be selected with elastic deformation of the seal.At the same time, also pay attention to the width of the sealing surface.The reason is that the contact surface of the sealing pair is not completely consistent, when the width of the sealing surface increases, it is necessary to increase the sealing force required.
2. Pressure of sealing surface
The specific pressure of sealing surface affects the valve sealing performance and service life.Therefore, the sealing surface pressure is also a very important factor.Under the same conditions, too much pressure will cause valve damage, but too little pressure will cause valve leakage.Therefore, we need to take full account of the appropriate ratio of pressure in the 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 hydrophilicity.Temperature change not only affects the relaxation of the sealing pair and the change of the size of the parts, but also has a close relationship with the viscosity of the gas.The viscosity of gas increases or decreases with the increase or decrease of temperature.Therefore, in order to reduce the influence of temperature on the sealing performance of the valve, we should design the sealing pair into elastic seats and other valves with thermal compensation.Viscosity is related to the permeability of a fluid.Under the same conditions, the greater the viscosity, the less permeable the fluid will be.The hydrophilicity of the surface is to show when there is a film in metallic surface, want to remove this film.Because this thin film of oil can destroy the surface hydrophilic, resulting in blocked fluid channels.
4. Quality of sealing pair
The quality of the sealing pair mainly refers to the selection of materials, matching, manufacturing accuracy on the check.For example, the disc fits well with the seat sealing surface to improve tightness.The circular waviness is characteristic, is its labyrinth seal performance is good.