Lift plug valves have a variety of structural forms, lift plug valves according to the sealing surface of the material is divided into two kinds of soft seal and hard seal. When the basic principle is turned on, the cock rises, the cock rotates 90 degrees to the full opening of the valve to reduce the friction with the sealing surface of the valve body; when the valve is closed, the cock rotates 90 degrees to the closed position and then descends to seal with the valve body Surface contact to seal. 1, double-sealed lifting plug valve Double-sealed lifting plug valve for the soft seal structure. The plug body is a combination of three plates made of cylindrical plug body, on both sides of the plate inlaid rubber sealing surface, the middle of the cylindrical wedge plug. When the valve is opened, the driving mechanism causes the cock to ascend, driving the two side boards to close together, so that the combined plug body and the valve sealing surface are separated, and then the plug body is driven to rotate by 90 degrees to the fully open valve position. When closing the valve, the transmission mechanism rotates the combination plug body to the closed position by 90 degrees, and then pushes the plug body to descend. After the two side plates come into contact with the bottom of the valve body no longer moves downwards, the intermediate wedge plug continues to descend and pushes the two side plates Phase import and export side of the move, so that the side of the soft sealing surface and valve body sealing surface contact is compressed and reach the seal. Double sealed plug-in valve with double blocking and exhaust function, the valve is equipped with pressure equalization device to prevent abnormal pressure system, and can reduce the resistance of the valve opening and closing moment. As the seal is compressed metal surface contact with each other, the valve has a fire safety function. Valve maintenance is very convenient, can not remove the valve body from the pipeline under the circumstances, by removing the bottom of the valve body can remove both sides of the plate from the body replacement. It is also widely used in oil, gas, metallurgical and mining, gas engineering, light industry and textile, shipyard, food and environmental water treatment and other industries for regulation, opening and closing pipeline fluid purposes. 2, the hard seal lift plug valve metal hard seal lift plug valve seat sealing surface on both sides can be sealed, the use of the valve from the media flow restrictions. Metal hard seal lift plug valve is closed, the hand wheel and stem through the valve seat sealing surface pressure, by increasing the seal pressure, the plug valve can have better sealing performance. Seat sealing surface convex, easy to clean the sealing surface, the sealing surface is not easy to accumulate crystalline media, or solid particles. Often used in high temperature chemical equipment occasions. There are several types of hard-seal poppet valves that are commonly available. A. Handwheel handle-type plug-in valve lift, the working principle is: rise, so that the cock and the valve fully open. Turn the handle closed to turn the cock 90 degrees to the closed position, then turn the gear handle to lower the cock to seal. During the process of valve opening and closing again, the cock and valve seat are separated, so the opening and closing of the valve is very easy, and the sealing surface is not easy to scratch during opening or closing, and the valve has a long service life. However, the use of small handle torque, so the nominal size of the valve is usually not large. Handwheel handle lift plug valve compact structure, small size, small fluid resistance. B. Mechanical cross-drive pop-up plug valve, the working principle is: When the valve is opened, the screw thread of the valve stem rotates the plug body. Plug and valve sealing surface and then drive the cock to rotate 90 degrees to fully open the valve. When the actuator is closed, the cock is rotated 90 degrees to the closed position, the cock is no longer rotated, and the driving force rotates the thread to lower the cock so as to be in contact with the sealing surface of the valve body. Mechanical cross transmission can be connected to the cylinder, electric devices, hydraulic systems for remote control. Mechanical cross-drive pop-up plug valve to solve the lack of input drive torque limit, so that the valve to large diameter and high pressure direction. Mechanical cross-drive poppet cock plug channel and the diameter of the same pipe, fluid resistance, ease of pigging. In the oil and gas long-distance pipeline development is growing. More Keyword Search: Plug Valve
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