In this paper, the characteristics of all-metal bidirectional pressure butterfly valve are analyzed in detail. If you think the answer is helpful to you, please give a compliment to the American Witton VTON valve.
In the selection of hard seal butterfly valve, there are generally requirements such as high temperature, low temperature, strong corrosion, strong erosion and long life. In some special occasions, higher requirements are put forward for the sealing of metal hard seal butterfly valve, which must bear pressure in both directions. At present, metal hard seal butterfly valve in the domestic market mostly adopts double eccentric and three-dimensional eccentric sealing principles. These two sealing structures are in the state of positive flow of media, and the sealing effect is good. When the medium is in a countercurrent state, the pressure of the medium produces an eccentric moment on the butterfly plate, which is not conducive to the sealing of the valve. In addition, due to the gap problem in processing, the reverse sealing performance is greatly reduced.
Hard seal butterfly valve
Bidirectional metal sealing butterfly valve is designed based on the principle of automatic grinding and sealing compensation when the valve is opened and closed, combined with the structural characteristics of gate valve, telescopic ball valve, orbital ball valve and other products. It can be sealed bi-directionally, and is widely used in occasions requiring bi-directional sealing, wear resistance, corrosion resistance and long service life. For example, imported wafer hard seal butterfly valve and imported butt welding metal hard seal butterfly valve.
I. Structure Diagram of Track Wedge Bidirectional hard seal butterfly valve
Figure 1 Track Wedge Bidirectional hard seal butterfly valve Structure Diagram (1. Spring yellow locating pin 2. Dovetail groove contraction mechanism 3. Double valve seat sealing structure 4. Spiral lifting mechanism)
Second, the working principle
The locating pin can ensure that the butterfly plate will not fall due to the gravity of the butterfly plate, and the end of the lower valve stem can be provided with an adjusting block to ensure the fixed position of the butterfly plate. During the whole opening and closing process, the valve stem moves vertically in a straight line by means of the dovetail contraction mechanism and the spiral lifting track, and the butterfly plate retracts to the center and leaves the valve seat by means of the dovetail contraction mechanism and the spiral lifting track. In this process, the sealing surface is separated first and then opened, which ensures that there is always a gap from sealing to instantly leaving the valve seat without friction, so the sealing surface of the valve is not worn, with long service life and low torque. In addition, due to the action of the valve stem wedge and dovetail groove, the forced sealing force on the valve is increased, the sealing specific pressure is improved, and the bidirectional sealing is realized.
The combined sealing ring can take many forms according to the needs of users, such as soft sealing ring with PTFE as the main material, multilayer sealing ring laminated with stainless steel and flexible graphite or integral stainless steel all-metal sealing ring. Symmetrically arranged left and right butterfly plates are respectively attached to the seals of symmetrically arranged left and right valve seats in the valve body, and two seals are formed without eccentricity, thus greatly improving the reliability of sealing performance, and the butterfly plates have two-way zero leakage.
Third, characteristics
Two-way hard seal butterfly valve can also add a water seal device in the middle of the valve body. In case of emergency or pipeline maintenance, water can be injected into the middle cavity, which plays the role of safety guarantee and dual-purpose of one valve.
Wedge-type bi-directional metal sealing butterfly valve adopts double butterfly plate full conical sealing surface structure, which can realize continuous grinding and self-correction of butterfly plate sealing surface and valve body sealing surface during valve opening and closing, and improve service life. In the process of operation, the operating torque is reduced because the medium pressure helps to open the valve.
Therefore, the sealing structure of two-way metal sealing butterfly valve is novel and unique, and the double butterfly plate has the function of two-way sealing, which is more suitable for high temperature and high pressure working conditions. The valve has good manufacturability and low design and manufacturing cost, and it is a hard seal butterfly valve with high technical parameters and high performance suitable for industrial conveying system.