1. Dimensional parameters
In order to meet the industrial requirements of high temperature, low temperature, strong corrosion, strong erosion and long life, metal-sealed butterfly valves have become one of the fastest growing valve varieties in recent years. In some special occasions, higher requirements are placed on the sealing of metal hard-seal butterfly valves, which must bear pressure in both directions. At present, metal hard-seal butterfly valves on the domestic and foreign markets mostly adopt double eccentric and three-dimensional eccentric sealing principles. Both sealing structures have better sealing effects when the medium is in the forward flow state; when the medium is in the counterflow state, due to the The pressure acts on the butterfly plate to produce an eccentric moment, which is not conducive to the sealing of the valve. Furthermore, due to the gap problem in machining, the reverse sealing performance is greatly reduced.
2. Structural characteristics
The wedge-type two-way metal seal butterfly valve (shown in Figure 1) is designed based on the automatic grinding seal compensation theory when opening and closing the valve, combined with the structural features of gate valves, expandable ball valves, orbital ball valves and other products.
Orbital wedge type two-way hard seal butterfly valve structure diagram
Figure 1 Structural diagram of orbital wedge type two-way hard seal butterfly valve (1. Spring positioning pin 2. Dovetail groove contraction mechanism 3. Double seat sealing structure 4. Spiral lifting mechanism)
The elastic positioning pin can ensure that the butterfly plate will not fall due to the gravity of the butterfly plate. An adjustment block can also be set at the end of the lower valve stem to ensure that the position of the butterfly plate is fixed. During the entire opening and closing process, the valve stem relies on the dovetail groove shrinking mechanism and the spiral lifting track to complete vertical linear motion, while the butterfly plate must rely on the dovetail groove shrinking mechanism and the spiral lifting track to shrink toward the center and separate from the valve seat. During this process, the sealing surface The method of first disengaging and then opening is used to ensure that the gap is always maintained from sealing to instantaneous separation from the valve seat without friction, so the valve sealing surface has no wear, long service life and low torque. Moreover, due to the action of the wedge-shaped block and the dovetail groove of the valve stem, the forced sealing force is increased on the valve, the sealing specific pressure is increased, and two-way sealing is achieved.
The combined sealing ring can be in various forms according to the user’s needs, such as a soft sealing ring made of polytetrafluoroethylene as the main material, a multi-layer sealing ring made of stainless steel and flexible graphite layers, or an integral stainless steel all-metal sealing ring. . Relying on its symmetrically arranged left and right butterfly plates, they are sealed with the symmetrically arranged left and right valve seats in the valve body, without eccentricity, forming two seals, thereby greatly improving the reliability of the sealing performance, and the butterfly plates have zero leakage in both directions.
This product can also add a water sealing device in the middle of the valve body, which can fill the middle cavity with water in the event of an emergency or pipeline maintenance, playing the role of safety guarantee and dual-purpose valve.
The wedge-type two-way metal seal butterfly valve adopts a double butterfly plate full cone sealing surface structure, which can realize the continuous grinding and self-correction of the butterfly plate sealing surface and the valve body sealing surface during the switching process of the valve, thereby improving the service life. During the operation process, the medium pressure helps the valve open, so the operating torque is reduced.
3. Summary
The wedge-type two-way metal seal butterfly valve has a novel and unique sealing structure. The double butterfly plates have a two-way sealing function, so it is more suitable for high temperature and high pressure working conditions. The valve has good processing technology and low design and manufacturing costs. It is a hard-sealed butterfly valve suitable for high-tech parameters and high-performance industrial conveying systems.