The butterfly valve has a variety of sealing forms to adapt to different working conditions and media requirements. The following are the main sealing forms of butterfly valves
1. Rubber seal
Features: Rubber sealing ring is usually installed around the butterfly plate, through the contact with the valve body sealing surface to achieve sealing. The rubber seal has good elasticity and wear resistance.
Application: Suitable for fluid control at low pressure and normal temperature.
2.Polytetrafluoroethylene (PTFE) seal
Features: Polytetrafluoroethylene seal has excellent corrosion resistance, high temperature resistance and low friction coefficient.
Application: Suitable for the control of corrosive media in chemical, petroleum and pharmaceutical industries. The PTFE seal ring is usually mounted on the butterfly plate to form a seal with the body sealing surface.
3. Metal seal
Features: Metal sealed butterfly valves are usually used in high temperature, high pressure and high corrosive conditions. Metal sealing rings can be made of stainless steel, alloy steel and other materials, with high strength and corrosion resistance.
Application: Often used in chemical, electric power and petrochemical fields.
4. Elastic seal
Features: The sealing ring made of elastic material (such as rubber or fluorine rubber) has good sealing performance and wear resistance.
Application: Suitable for medium and high pressure and high temperature fluid control.
5. Multi-layer seal
Features: In order to improve the sealing performance of the butterfly valve, sometimes multi-layer sealing structure is used. This form of sealing is usually composed of sealing rings of different materials, such as rubber and PTFE combinations, to provide a better sealing effect.
Application: Select the suitable sealing form according to the specific working conditions and fluid properties.
6. Classification of sealing principle
In addition to the classification by material, the seal of the butterfly valve can also be classified from the sealing principle, mainly including the following:
Specific pressure compaction by interference volume: Through the interference fit between the seal and the valve body or the control plate, enough specific pressure is generated to achieve seal.
By direct pressure or torque to seal the pair: such as double eccentric butterfly valve, three eccentric butterfly valve, etc., through the torque generated by rotating the valve stem or external direct pressure, the seal pair will be compressed to achieve sealing.
The Poisson effect uses the medium to press on the sealing ring: The pressure of the medium itself is used to act on the sealing ring to enhance the sealing effect. The larger the upstream and downstream pressure difference, the better the sealing effect.
7. Classification of structure and form
Butterfly valve seal structure forms also have single eccentric seal, double eccentric seal, three eccentric seal, variable eccentric seal, etc. These structural forms have their own characteristics in sealing principle and sealing effect, suitable for different working conditions and medium requirements.
