What Is Soft Seal Butterfly Valve?

What Is Soft Seal Butterfly Valve?

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The butterfly plate of the soft seal butterfly valve is installed in the diameter direction of the pipeline and rotates around the axis in the cylindrical channel of the valve body, whose rotation angle is between 0 ° and 90 °. When the rotation angle is 90 degrees, the ductile iron butterfly valve is fully open.



Brief Introduction of Butterfly Valve


At present, as a component used to realize the on-off and flow control of pipeline system, soft sealing pneumatic actuated butterfly valve has been widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower, and so on, whose sealing materials are rubber and polytetrafluoroethylene. Due to the limitation of structural characteristics, soft seal butterfly valve is not suitable for high temperature, high pressure, corrosion resistance, and wear resistance industries. At present, three eccentric metal hard seal water butterfly valve is appeared, whose valve body and valve seat are connected components. Compared with the traditional solenoid butterfly valve, three eccentric metal hard seal butterfly valve has the characteristics of high temperature resistance, light operation, and no friction. Because it compensates the sealing with the increase of the torque of the transmission mechanism when it is closed, the sealing performance and service life of the fire protection butterfly valve are improved.



Problems of Butterfly Valve in use


•Because the multi-layer stacked seal ring is fixed on the valve plate, the medium forms a positive erosion on its sealing surface when the valve plate is in the normally open state. The erosion of the soft sealing belt in the sheet metal interlayer will directly affect the sealing performance.


•Restricted by structural conditions, butterfly isolation valve is not suitable for making valve with diameter less than DN200.


•The sealing between the sealing surface of the valve plate and the valve seat depends on the torque of the transmission device to make the valve plate press toward the valve seat, so the higher the medium pressure is, the tighter the seal extrusion is. When the increase of medium pressure and the unit positive pressure between valve plate and valve seat is less than medium pressure, the seal begins to leak.


•The feature of high performance soft seal butterfly valve with limit switch is that the valve seat sealing ring is composed of multi-layer stainless steel sheets on both sides of the soft T-shaped sealing ring.


•The spring fixed between the pressure plates of the adjusting ring and the adjusting bolt are assembled together, which not only effectively compensates the tolerance zone between the shaft sleeve and the valve body under the medium pressure, but also solves the sealing problem of the wafer lug butterfly valve in the process of two-way exchanging medium transportation.


•The soft T-type multi-layer stainless steel sheet on both sides has the dual advantages of metal hard seal and soft seal, which has zero leakage sealing performance at both low and high temperatures. The test shows that the pressure on the sealing surface is caused by the torque of the transmission device and the medium pressure when the medium flow direction is the same as the rotation direction of the butterfly plate. When the positive medium pressure increases, the tighter the extrusion between the inclined conical surface of the valve plate and the sealing surface of the cast iron butterfly valve, the better the sealing effect.

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