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The closing element of a globe valve is a plug-shaped disc; its sealing surface is either flat or conical. The disc moves in a straight line along the center line of the valve seat, thereby enabling opening and closing. In pipelines, it is primarily used to shut off the flow of fluid. It features a simple structure, easy installation, convenient operation, smooth flow, low flow resistance, and other advantages due to its straightforward design. Structural principle of plastic globe valves A globe valve is a type of valve in which the closing element (valve disc) moves along the center line of the valve seat. Based on this manner of movement of the valve disc, the change in the valve seat opening is directly proportional to the stroke of the valve disc. Due to the relatively short opening and closing stroke of the valve stem in this type of valve, as well as its highly reliable shut-off function, and because the change in the valve seat orifice is proportional to the stroke of the valve disc, it is very suitable for regulating flow rate. Therefore, this type of valve is very suitable for use in cutting off or regulating flow, as well as for throttling. 1. No friction during opening and closing. This feature completely solves the problem of poor sealing in traditional valves, which is caused by friction between the sealing surfaces. 2. Upper-mounted structure. Valves installed on pipelines can be inspected and repaired directly online, which helps to reduce plant downtime and lower costs. 3. Single-seat design. It eliminates the problem of the medium in the valve cavity affecting safety of use due to abnormal pressure rise. 4. Low-torque design. The valve stem, with its specially designed structure, allows the valve to be easily opened and closed using only a small handle. 5. Wedge-shaped sealing structure. The valve seals by using the mechanical force provided by the valve stem to wedge the ball against the valve seat, ensuring that its sealing performance is not affected by changes in pipeline pressure differences; thus, reliable sealing is maintained under various operating conditions. 6. Self-cleaning structure for the sealing surface. When the ball is tilted away from the valve seat, the fluid in the pipeline flows evenly around the ball’s sealing surface at 360°, which not only eliminates the localized scouring of the valve seat by high-speed fluid but also removes any deposits accumulated on the sealing surface, thereby achieving self-cleaning. 7. For valve diameters of DN50 and below, the valve stems used for opening and closing are made entirely of plastic; for diameters above DN65, they are made of plastic-coated steel. All components that come into contact with fluid flow are made of plastic, providing excellent corrosion resistance. 8. The material is corrosion-resistant plastic (FRPP, CPVC, UPVC, PPH, PVDF). Working principle of plastic globe valves: A. Opening process: 1. In the closed position, the valve body is pressed against the valve seat by the mechanical force exerted by the valve stem. 2 When the handwheel is turned counterclockwise, the valve stem moves in the opposite direction; its angular flat surface at the bottom causes the ball to disengage from the valve seat. The 3 valve stem continues to rise and interacts with the guide pin in the spiral groove of the valve stem, causing the ball to begin rotating frictionlessly. 4 Until it reaches the fully open position, the valve stem is lifted to its extreme position, and the ball rotates to the fully open position. B. Shutdown process: 1. To shut down, rotate the handwheel clockwise; the valve stem begins to descend, causing the ball to move away from the valve seat and start rotating. 2. Continue to turn the handwheel; the valve stem, acted upon by the guide pins embedded in the helical grooves on it, causes both the valve stem and the gate to rotate 90° at the same time. 3 By the time it was about to be shut down, the gate had already rotated 90° without making contact with the valve seat. During the last few turns of the handwheel, the angular surface at the bottom of the valve stem mechanically presses against the ball, forcing it to fit tightly against the valve seat and achieving a complete seal.