globe valve The opening and closing part is a ball with a circular channel, which rotates around the axis perpendicular to the channel, and the ball rotates with the valve rod, so as to achieve the purpose of opening and closing the channel. The ball valve only needs us to use 90 degree rotation operation and very small rotation torque to close tightly. According to the actual working condition data needs, the drive technology devices with different assembly methods can form ball valves with different enterprise control research methods, such as electric ball valve, pneumatic ball valve, hydraulic ball valve, etc.
According to the structure, it can be divided into:
1、 Floating ball valve
The ball valve floats under the medium pressure, which can produce a certain displacement of the ball and the extrusion port end, so as to ensure the sealing surface of the outlet end of the seal.
The floating ball valve has simple structure and good sealing performance, but the ball bears the load of social working environment medium, and all information is transmitted to the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material enterprise can withstand the actual working load of the ball medium. This economic structure is widely used in medium and low pressure ball valves.
2、 Fixed ball valve
The ball of ball valve is fixed and does not move after compression. The fixed ball valve is equipped with floating valve seat. After medium pressure, the valve seat moves to make the sealing ring close to the ball to ensure sealing. The ball is usually used on the upper and lower bearings, and the operating torque distance is small, which is suitable for high pressure and large diameter valves.
In order to reduce the operating torque of ball valve and improve the effectiveness of sealing, a kind of oil sealed ball valve has appeared in recent years. It not only injects special lubricating oil between the sealing surfaces to form an oil film, that is to improve the sealing performance and reduce the operating torque, but also is more suitable for high-pressure large diameter ball valves.
3、 Elastic ball valve
The ball valve is flexible. And a ball valve seat ring is made of metal material according to the requirement that the pressure medium itself has reached less than the sealing element. The sealing pressure ratio is large, and the external force must be applied. Such valves are designed for high temperature and high pressure platforms.
Elastic analysis of the sphere is to obtain psychological elasticity by opening an elastic slot at the lower end of the inner wall of the sphere. When a channel is closed, the wedge head of the valve stem is used to make the ball open and the valve seat is pressed to improve the sealing. Before rotating the ball, loosen the wedge head, and the ball will return to its original shape, so that there is no small gap between the ball and the valve seat, which can reduce the trade friction on the working face of the mechanical seal and the torque during operation.