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Soft seal structure and performance in butterfly valve
- Apr 20, 2018 -

Butterfly valves are widely used as the best device for cutting off or adjusting the flow rate in the medium pipelines of urban construction, petrochemical, metallurgy, and electric power industries. The construction of the butterfly valve itself is the most ideal opening and closing part in the pipeline, and is the development direction of the opening and closing part of the pipeline today.

The first is the soft seal butterfly valve with single eccentric structure. The bisector of the valve seat seal cross section or the disc thickness direction is relatively eccentric with the rotary center of the valve stem, so that during the opening process of the butterfly valve, the butterfly plate sealing surface gradually disengages from the valve seat sealing surface. When the butterfly plate rotates to 20~25°, the sealing surface of the butterfly plate completely separates from the sealing surface of the valve seat, so that during the opening process of the butterfly valve, relative mechanical abrasion and extrusion between the two sealing surfaces are greatly reduced, so that the sealing performance of the butterfly valve is achieved. Can be improved. This design mainly relies on the elastic deformation between the butterfly plate and the valve seat to ensure the sealing of the butterfly valve.

On the basis of a single eccentric butterfly valve, the center of the valve flow channel is offset relative to the center of rotation of the butterfly plate, so that the butterfly valve forms a cam effect during the opening process, so that the sealing surface of the butterfly plate exits the valve seat faster than the single eccentric structure. Sealing surface. When the butterfly plate rotates to 8°~12°, the butterfly plate sealing surface completely disengages from the valve seat sealing surface. The design of this structure greatly reduces the relative mechanical wear and the extrusion deformation between the two sealing surfaces, so that the sealing performance of the butterfly valve is further improved.

On the basis of the double eccentric butterfly valve, the center line of the valve seat sealing surface forms an angle eccentricity with the centerline of the valve, so that during the opening process of the butterfly plate, the sealing surface of the butterfly plate immediately disengages from the valve seat sealing surface at the moment of opening, and The valve seat sealing surface is contacted and pressed only for a moment of closing. This unique combination of eccentricity makes full use of the cam effect to completely eliminate the mechanical friction and scratches between the two sealing surfaces of the butterfly valve seal when the valve is opened and closed, eliminating the possibility of wear and leakage. The variable-squeeze seal is a torque seal, and the adjustment of the seal specific pressure is achieved by adjusting the applied drive torque, so that the sealing performance and service life of the triple-eccentric structural seal butterfly valve are greatly improved.

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