1. Due to the multi-layer soft and hard laminated seal ring fixed on the valve plate, when the valve plate is normally open, the medium will form a positive scour on its sealing surface, and the soft sealing band in the metal interlayer will be scoured, which will directly affect the sealing performance.
2. Limited by the structural conditions, the structure is not suitable for the valve with diameter below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large.
3. Due to the principle of three eccentric structure, the sealing between the sealing surface of the valve plate and the valve seat depends on the torque of the driving device to press the valve plate to the valve seat. In the positive flow state, the higher the medium pressure, the tighter the seal extrusion. When the medium flow counter current, with the increase of medium pressure, the unit positive pressure between valve plate and valve seat is less than the medium pressure, the seal begins to leak.
The high performance three eccentric bidirectional hard sealing butterfly valve is characterized in that the valve seat sealing ring is composed of multilayer stainless steel sheets on both sides of the soft T-shaped sealing ring. The sealing surface of valve plate and valve seat is inclined conical structure, which is overlaid with heat-resistant and corrosion-resistant alloy materials on the inclined conical surface of valve plate; the structure is composed of spring fixed between the pressure plate of regulating ring and adjusting bolt on the pressure plate.
This structure effectively compensates the tolerance zone between the shaft sleeve and the valve body and the elastic deformation of the valve stem under the medium pressure, and solves the sealing problem of the valve in the process of two-way exchange medium transportation. The sealing ring is composed of soft T-shaped multi-layer stainless steel sheets on both sides, which has the double advantages of metal hard sealing and soft sealing. It has zero leakage sealing performance no matter at low or high temperature.