First, because the multi-layer soft and hard stack seals are fixed on the valve plate, when the valve plate is always open, the media forms a frontal flush against its sealing surface, and after the soft sealing tape in the metal plate interlayer is washed, it directly affects the sealing performance.
Second, subject to structural constraints The structure is not adapted to the following diameter DN200 valves, because the overall structure of the valve plate is too thick, large flow resistance.
Third, due to the principle of triple eccentric structure, the seal between the sealing surface of the valve plate and the valve seat is to press the valve plate against the valve seat by the torque of the transmission device. In the normal flow state, the higher the medium pressure, the tighter the seal extrusion. When the medium of the flow passage is reversed, the seal begins to leak when the positive pressure between the valve plate and the valve seat is smaller than the pressure of the medium as the pressure of the medium increases.
The high performance midline butterfly valve is characterized in that: the valve seat seal ring is composed of multi-layer stainless steel plates on both sides of a soft T-shaped seal ring.
The sealing surface of the valve plate and the valve seat is an inclined conical structure, and a temperature-resistant, corrosion-resistant alloy material is surfacing on the oblique conical surface of the valve plate; the structure of the spring fixed between the adjusting ring pressure plate and the adjusting bolt of the pressure plate is assembled together. This structure effectively compensates the tolerance band between the 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 of the medium.
The soft T-shaped multi-layer stainless steel plate on both sides forms a seal ring, which has the dual advantages of metal hard seal and soft seal, and has zero leakage sealing performance under both low temperature and high temperature conditions. The test proves that the positive flow state of the pool (the direction of flow of the medium is the same as the direction of rotation of the disc), the pressure of the sealing surface is generated by the torque of the transmission device and the pressure of the medium on the valve plate. When the pressure of the medium increases, the tighter conical surface of the valve plate and the seat sealing surface are squeezed tighter, and the sealing effect is better.
When in the reverse flow state, the seal between the valve plate and the valve seat is pressed against the valve seat by the torque of the drive device. With the increase of the reverse medium pressure, the positive pressure between the valve plate and the valve seat is less than the medium pressure, the deformation of the spring of the adjustment ring after being loaded can compensate the tight pressure between the valve plate and the valve seat sealing surface. Plays automatic compensation.
Therefore, unlike the prior art, the present invention does not install a soft and hard multi-layer seal ring on the valve plate, but directly mounts on the valve body. It is an ideal two-way hard seal method to add an adjustment ring between the pressure plate and the valve seat. . The midline butterfly valve will replace the gate valve and ball valve.