Since the multi-layer soft and hard stacking sealing ring is fixed on the valve plate, when the valve is normally open, the medium forms a frontal erosion on its sealing surface, and the soft sealing belt in the interlayer of the metal sheet is directly affected by the erosion, and the sealing performance is directly affected; Limited by the structural conditions, this structure is not suitable for valves with a diameter of less than 200mm, because the overall structure of the valve is too thick and the flow resistance is large.
Because of the principle of three-eccentric structure, the sealing surface of the valve plate and the seat is sealed by the torque of the transmission device to make the valve plate pressure to the seat. In the positive flow state, the higher the medium pressure is, the tighter the seal is squeezed. When the media flow upstream, with the increase of the medium pressure, the unit positive pressure between the valve plate and the seat is less than the medium pressure, the seal began to leak.
