The meaning of the stop valve, what is the stop valve?

The shut-off valve, also known as the shut-off valve, is a forced-sealing valve, so when the valve is closed, pressure must be applied to the disc to force the sealing surface to not leak. When the medium enters the valve from below the disc, the resistance that the operating force needs to overcome is the frictional force between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the valve stem The diameter of the valve should be large, otherwise the valve stem will bend failure. According to the connection mode, it is divided into three types: flange connection, threaded connection, and welding connection. After the appearance of the self-sealing valve, the medium flow direction of the shut-off valve changes from above the valve disc into the valve cavity. At this time, under the action of the medium pressure, the force of closing the valve is small, and the force of opening the valve is large, and the diameter of the valve stem can be corresponding To reduce.

At the same time, under the action of the medium, this type of valve is also tighter. my country's valve "Sanhua" once stipulated that the flow direction of the stop valve should be from top to bottom. When the shut-off valve is opened, the opening height of the disc is 25% to 30% of the nominal diameter. The flow has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the fully open position of the shut-off valve should be determined by the stroke of the valve disc.

The opening and closing part of the stop valve (Globe Valve) is a plug-shaped valve disc with a flat surface or a sea cone on the sealing surface, and the valve disc moves linearly along the center line of the valve seat. The movement form of the valve stem, (common name: dark stem), also has a lifting and rotating rod type, which can be used to control various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal, and radioactive media. flow.

Therefore, this type of shut-off valve is very suitable for shutting off or regulating and throttling. Since the opening or closing stroke of the valve stem of this type of valve is relatively short, and it has a very reliable cut-off function, and because the change of the valve seat port is in direct proportion to the stroke of the valve disc, it is very suitable for flow adjustment.