First, Because the multi-layer soft and hard overlapping sealing ring is fixed on the valve plate. When the valve plate is normally open, the medium forms a positive scouring on the sealing surface. And the soft sealing belt in the sandwich of the metal sheet is washed, which directly affects the sealing performance.

Two, limited by structural conditions, the structure is not suitable to do diameter DN200 below the valve. The reason is that the overall structure of the valve plate is too thick, the flow resistance is large.

Three, because of the principle of three eccentric structure. The sealing between the sealing surface of the valve plate and the seat is made by the torque of the transmission device to press the valve plate to the seat. In the positive flow state, the higher the medium pressure, the tighter the seal extrusion. When the flow channel medium countercurrent with the increase of medium pressure between the valve plate and seat unit positive pressure is less than the medium pressure, the seal begins to leak. The high performance three eccentric hard seal butterfly valve is characterized in that the seat sealing ring is composed of multiple layers of stainless steel on both sides of the soft T-ring.

The sealing surface of the valve plate and the valve seat is a inclined conical structure. And the temperature resistant and corrosion resistant alloy material is surfacing on the inclined conical surface of the valve plate. The structure of the spring fixed between the adjusting ring platen and the adjusting bolt on the platen. This structure effectively compensates the elastic deformation of the tolerance zone between the shaft sleeve and the valve body and the valve stem under the medium pressure. And solves the sealing problem of the valve in the two-way interchangeable medium conveying process.

The sealing ring is composed of multiple layers of stainless steel sheets on both sides of the soft T type. Which has the double advantages of hard metal seal and soft seal. It has zero leakage sealing performance in both low and high temperature conditions. The test proves that when the tank is in a positive flow state. The pressure of the sealing surface is caused by the action of the torque of the transmission device and the pressure of the medium on the valve plate. When the positive medium pressure increases. The more tightly the inclined cone surface of the valve plate and the sealing surface of the valve seat are squeezed. The better the sealing effect is. When countercurrent, the seal between the valve plate and the seat depends on the torque of the driving device to press the valve plate against the seat.

With the increase of the reverse medium pressure, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure. The adjustment ring spring after loading the deformation energy stored to compensate the valve plate and the valve seat sealing surface of the tight pressure plays an automatic compensation role. Therefore, the utility model does not install the soft and hard multilayer sealing ring on the valve plate like the existing technology. But is directly installed on the valve body, and an adjustment ring is added between the pressure plate and the seat. Which is a very ideal bidirectional hard sealing mode. It will replace gate valves and ball valves.