American Standard flanged ball valve is a new type of valve is widely used in recent years, it has the following advantages: 1. Fluid resistance, its drag coefficient with the same pipe lengths are equal. 2. Simple structure, small size and light weight. 3. Compact and reliable valve sealing surface material widely used plastic, sealing, has also been widely used in the vacuum system. 4. Easy to operate, opening and closing rapidly, from fully open to fully closed as long as the rotation of 90 °, to facilitate remote control. 5. Easy maintenance, simple ball valve, seals are generally activities, the removal replacement is more convenient. 6. When fully open or fully closed, the sealing surface and the dielectric isolation ball and seat, through the media, will not cause erosion of the valve sealing surface. 7. Wide range of applications, from small diameter to a few millimeters to a few meters from high vacuum to high pressure can be applied. This type valve in the pipe should generally be installed horizontally. American Standard flanged ball valve classified by structural classification of a floating ball valve ANSI flanged ball valve is floating in the medium under pressure, the ball can produce a certain displacement and pressed at the outlet end of the sealing surface to ensure the outlet end seal. Simple floating ball valve structure, good sealing, but the ball all bear the load of the working medium to pass the exit ring, so to consider the ring material can withstand the work load of the media sphere. This structure is widely used in low-pressure valve. Second, the fixed ball valve ANSI flanged ball valve is fixed, no movement after compression. All with a floating ball valve fixed valve seat, by medium pressure, the valve seat to move, so that the ball seals pressed on, in order to ensure the seal. Usually with the ball, the lower shaft with bearings, operating torque, suitable for high pressure and large diameter valves. To reduce the valve operating torque and increase the reliability of the seals, valve seals has emerged in recent years, both the pressure injection of a special lubricant between the sealing surface to form a layer of film that enhances the seal, but also reduce operating torque more suitable for large diameter high pressure valve. Third, the elastic ball valve ANSI flange ball valve is resilient. Ball and seat ring are made of metal materials, sealing pressure than large, rely on the media itself has reached less pressure sealing requirements, must apply force. This valve is suitable for high temperature and high pressure medium. Elastic sphere is the sphere of the inner wall at the lower end of a resilient open slot, and access flexibility. When closing the channel, with the stem of the wedge-shaped head on and make the ball up the valve seat seal. Before turning the ball to loosen the wedge-shaped head, the ball along with restoration of the original prototype, so that small gap, sealing surface can reduce friction and operating torque between the ball and seat. American Standard flanged ball valve works like an open process in a closed position, the ball by the stem [wiki] machinery [/ wiki] pressure effect, pressed on the seat. 2 When the handwheel counterclockwise stem the reverse movement, its flat bottom corner to make the ball disengage the seat. 3 stem continues to rise, and the interaction between the valve stem and guide pin spiral groove, so that the ball began to rotate without friction. 4 up to the fully open position, the valve stem to the limit position, the ball rotated to the fully open position. Second, when you close the process a closed hand wheel clockwise, the stem and the ball began to fall away from the seat starts to rotate. 2 continues to rotate the handwheel stem being embedded in the spiral groove on its role of guide pins, so the stem and ball while rotating 90 °. 3 is about to shut down, the sphere has been in the case of non-contact with the valve seat is rotated 90 °. The last four laps hand wheel rotation, angular plane mechanically wedge at the bottom of the stem to the oppression of the ball, making it tightly pressed on the seat, to be completely sealed.