1. Due to the structural conditions, the structure is not suitable for making valves with diameters below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large.

2. Because the multi-layer soft and hard laminated sealing ring is fixed on the valve plate, when the valve plate is normally open, the medium will form a positive scouring on its sealing surface, and the soft sealing belt in the metal sheet interlayer will directly affect the sealing performance after being scoured.

3. Due to the principle of fluorine-lined butterfly valve, the sealing 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 positive flow state, the higher the medium pressure, the tighter the seal extrusion. When the medium in the flow path is countercurrent, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure with the increase of the medium pressure, the seal begins to leak.