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This post was last edited by 鎴戠編鎴戜换鎬р樅 on 2020-12-7 at 11:35. A ball valve is a type of self-acting control valve; it evolved from a plug valve. Its closing element is a sphere, and the valve is opened or closed by rotating the stem by 90 degrees. Ball valves are primarily used in pipelines for cutting off, distributing, and changing the direction of flow of the medium. Ball valves with a V-shaped opening also exhibit excellent flow regulation capabilities. Ball valves can be opened and closed quickly, offer good sealing performance, have a simple structure, and exhibit low flow resistance; they are widely used in modern industrial applications. Based on their structural design, self-acting control valve ball valves can be classified into fixed-ball valves, floating-ball valves, track-ball valves, V-ball valves, eccentric hemispherical valves, three-way ball valves, four-way ball valves, and so on ； Based on the connection method, they are classified into flanged ball valves, wafer ball valves, threaded ball valves (internal thread), threaded ball valves (external thread), welded ball valves, clamp ball valves (usually sanitary-grade ball valves), and socket ball valves, among others ； Based on the sealing material, they can be divided into soft-sealed ball valves and metal hard-sealed ball valves. Soft-sealed ball valves are generally suitable for media at temperatures below around 150 degrees; for media at temperatures above 150 degrees, PPL sealing or metal sealing is used. For self-acting control valves with small diameter ball valves, floating ball valves are generally used; whereas for large diameter ball valves, fixed ball valves are often chosen due to the higher torque required to open and close them. This approach helps reduce the torque needed during operation and improves reliability. V-ball valves and eccentric half-ball valves can be used to regulate flow, while three-way ball valves and four-way ball valves are used to redirect the fluid. Common materials for ball valves include carbon steel, 304 stainless steel, and 316 stainless steel; for media with high corrosivity, the valve body and the ball are lined entirely with polytetrafluoroethylene. The driving methods for ball valves mainly include electric, pneumatic, and worm gear drive; for small-diameter manual ball valves, they are generally operated using a handle.