The working principle of the ball valve : the ball valve only needs to rotate 90 degrees and a small rotating torque to reach or cut the medium of the pipe. However, recent developments have designed ball valves to provide throttling and control flow.
The main features of the ball valve are its compact structure, reliable sealing, simple structure, sealing surface and spherical surface are often closed, not easily eroded by medium, easy to operate and maintain, suitable for general working medium such as water, solvent, acid and natural gas, and It is also suitable for mediums with harsh working conditions, such as oxygen, hydrogen peroxide, methane and ethylene, which are widely used in various industries. The ball valve body may be integral or combined.
Ball valve advantages : 1 . The fluid resistance is small, and the full-bore ball valve has substantially no flow resistance. 2 . The structure is simple, small in size and light in weight. 3 . Tight and reliable. It has two sealing faces, and the sealing surface material of the ball valve is widely used in various fluoroplastics, and has good sealing performance and can achieve complete sealing. It has also been widely used in vacuum systems. 4 . The operation is convenient, the opening and closing is rapid, and the rotation is 90 ° from full opening to full closing , which is convenient for long-distance control. 5 . The maintenance is convenient, the ball valve has a simple structure, and the sealing ring is generally movable, and the disassembly and replacement are relatively convenient. 6 . When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the medium does not cause erosion of the sealing surface of the valve. 7 . Since the ball valve is wiping during opening and closing, it can be used in a medium with suspended solid particles.
Ball valve classification and characteristics :
1. Floating ball valve : The ball of the valve is floating. Under the action of medium pressure, the ball can generate a certain displacement and press on the sealing surface at the outlet end to ensure the sealing of the outlet end. The floating ball valve has a simple structure and good sealing performance, but the load of the ball subjected to the working medium is all transmitted to the outlet sealing ring, so it is necessary to consider whether the sealing ring material can withstand the working load of the spherical medium, and when subjected to a high pressure shock. The sphere may be offset. This structure is generally used for medium and low pressure ball valves.
2. Fixed ball valve : The ball of the ball valve is fixed and does not move after being pressed. The fixed ball valve has a floating valve seat. After the medium pressure, the valve seat moves, so that the sealing ring is pressed against the ball to ensure the seal. Usually mounted on the upper and lower shafts of the ball, the operating torque is small, suitable for high pressure and large diameter valves. In order to reduce the operating torque of the ball valve and increase the reliability of the seal, oil seal ball valves have appeared in recent years, and the special lubricating oil is injected between the sealing faces to form an oil film, which enhances the sealing performance and reduces the operating torque. It is more suitable for high pressure and large diameter ball valves.
3. Elastic ball valve (ie track ball valve) : The ball of the ball valve is elastic. Both the ball and the seat ring are made of metal material, and the sealing pressure is very large. The pressure of the medium itself cannot meet the sealing requirements, and an external force must be applied. This valve is suitable for high temperature and high pressure media. The elastic sphere is made by opening an elastic groove at the lower end of the inner wall of the sphere to obtain elasticity. When the passage is closed, the wedge of the valve stem is used to open the ball and press against the seat to seal. Before the ball is rotated, the wedge head is loosened, and the ball is restored to its original shape, so that a small gap occurs between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.
4 , V -type ball valve : This ball valve belongs to the fixed ball valve, is also a single seat ball valve, the adjustment performance is good in the ball valve, the flow characteristics are equal percentage, the adjustable ratio is up to 100:1 . Its V -shaped slit has shearing action with the metal seat, especially suitable for media containing fibers, tiny solid particles, slurry.
5 , three-way ball valve : three-way ball valve has T and L type. The T -type enables three orthogonal pipes to communicate with each other and cut off the third channel to function as a split and merge. The L -shaped can only connect two pipes that are orthogonal to each other, and cannot simultaneously maintain the mutual connection of the third pipe, and only serves as a distribution.
Ball valve installation : 1) Remove the protective cover on both sides of the flange end and clean it with the valve fully open. 2 ) Before the installation of the ball valve with the actuator, the whole machine test should be carried out according to the specified signal (electricity or gas) (to prevent the use of vibration due to transportation). After passing the test, it can be installed on the line (wiring according to the electric actuator circuit diagram). 3) Before installing the pipe, flush and remove the remaining impurities in the pipe (these materials may damage the seat and the core). 4) During installation, please do not use the actuator part of the valve as a lifting point for lifting to avoid damage to the actuator and accessories. 5) This type of valve should be installed in the horizontal or vertical direction of the pipe. 6) The pipe near the installation point should not be drooped or subjected to external force. Pipe supports or supports can be used to eliminate the deviation of the pipeline. 7) After connecting with the pipe, cross-tighten the flange connection bolt with the specified torque.
