Small diameter hard seal ball valve product knowledge

1 Overview Ball valve in the petroleum, chemical, metallurgical and urban central heating and other industries have been widely used. But the sealing pair made of PTFE polymer material ball valve, can not be used for the temperature is greater than 280 ℃ or the medium is tiny granular transport conditions. The metal seal material as a hard seal on the valve, the ball will rotate due to the structure of a variety of different situations. Such as metal elastic seat seal structure, as the elastic seat and the ball did not form a gap between the ball, so the friction is great. Metal floating seat seal structure between the floating seat and the body is not easy to seal. Due to the large number of parts and complicated structure, the combined ball distraction seal structure increases the machining difficulty and manufacturing cost, especially the small-diameter hard seal ball valve. This structure obviously is not suitable. After repeated analysis and testing, and with the aid of CAD-assisted design, the Q47H cam eccentric single-seat fixed type hard-sealing ball valve was successfully developed. 2 Working principle Eccentric eccentric single seat ball center line relative to the valve body center line offset a, b, seat sealing surface eccentric b. When the valve stem rotates 90 ° clockwise around point O, the ball will rotate 90 ° and closely match with the sealing surface of the valve seat. When the friction torque between the seal pair and the friction torque between the filler and the valve stem is greater than the medium pressure Of the moment, the valve will achieve a reliable seal. As the valve seal cam eccentric structure, when the valve is opened, the ball quickly from the valve seat sealing surface. When the valve is closed, the ball quickly fits the seat sealing surface. So as to achieve a small opening torque, close the purpose of tight. 3 structural features small-caliber valve body cavity space is narrow, the usual structural design is not applicable. Therefore, the end of the valve stem is processed into a flat shape and has a short shaft. The ball body has a flat groove and a hole on the upper and the lower. The hole is used for fixing the ball body connected with the upper and the lower valve stems, limiting the freedom degree of the ball body. The role of media pressure. The flat groove cooperates with the stem to transmit the torque from the handle. 4 manufacture and processing of the coaxiality of the two holes and the centerline of the ball relative to the valve body centerline eccentricity tolerance requirements are more stringent, generally require boring machine or CNC machining. Before assembly, the sealing surface of the valve seat and the ball surface should be matched with the research surface. Then put the ball in the closed position, install the left valve body, adjust the gasket, tighten the screws, and the static pressure water does not leak, then the valve can be sealed under the seal test . 5 Conclusion Small diameter hard seal ball valve in line with existing domestic and international ball valve structure length, connection and connection dimensions of the relevant standards, the valve is not only suitable for conveying gaseous or liquid single-phase media, but also for gas-liquid mixed media and gas-liquid mixed medium. The valve has been used in metallurgical, textile and oil industries, the effect is good.