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Oil-lubricated hard-sealing plug valve
Oil-lubricated hard-sealing plug valves can be divided into conventional oil-lubricated plug valves and pressure-balanced plug valves. Special grease from the top of the plug body into the cone between the body and plug to form a film to reduce valve opening and closing torque, improve sealing and service life. Its working pressure up to 64MPa, the maximum working temperature up to 325 degrees, the largest caliber up to 600mm. 1, the conventional oil-lubricated plug valve A. Conventional hard-sealed plug valve, cock plug cones installed formally. In order to reduce the friction between the valve body and the plug sealing surface, the sealing structure of the valve is generally used to lubricate the valve seat. The high-pressure sealing oil injected from the high-pressure oil nozzle forms a high-pressure sealing ring around the cock, that is, there is a layer of oil film between the valve body and the plug cone surface, which can be closed and lubricated, and the opening and closing is easy. B. In order to further reduce the opening and closing force of the stopcock, the method of reducing the stopcock diameter is usually adopted. Therefore, the stopcock usually adopts a rectangular runner. This method increases the fluid resistance of the stopcock while reducing the opening and closing torque of the stopcock C. Stopcock Cone Sealing STL alloy or surface hardening technology to enhance the wear resistance and corrosion resistance of the sealing surface, long service life D. Rotor cone surface to the mirror surface, and the body seal Surface grinding, with a lower opening and closing torque. 2, pressure balanced plug valve In order to reduce the conventional hard seal plug valve torque, often using pressure balanced plug valve. In addition to the features of the conventional oil-lubricated plug valve, the pressure-balanced plug valve has the following features: A. The plug cone of a pressure-balanced plug valve is mounted in flip-flops. There is a check valve in the upper part of the cock plug cone. When the valve is closed, due to the poor cross-sectional area of ​​the plug cone, the high-pressure sealing oil is injected to lift the plug body upwards so that the sealing face of the plug body and the valve can be better sealed. B. At the moment when the valve is open, the pressure in the lower chamber of the valve is balanced with the pressure of the medium in the pipeline. The high-pressure sealing oil in the upper chamber causes the plug body to be pushed downwards so that a slight gap occurs between the plug cone and the sealing surface of the valve body, Torque when rotating the plug body will be effectively reduced. Can also protect the seal pair. C. In high temperature conditions, the thermal expansion of the cock can be absorbed by its lifting, to avoid wedging the seal pair. Oil-lubricated hard-sealing plug valves, although the use of oil lubrication can reduce the opening and closing torque, but it may cause contamination of the medium. Therefore, select the actual conditions for sealing oil. More Keyword Search: Plug Valve