What Structures Does Flange Ball Valve Have? What Are Its Characteristics?
Ball Valve can be divided into three categories according to the structure:
1. Floating ball valve
The ball of the ball valve is floating. Under the pressure of the medium, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet to ensure the sealing of the outlet. The floating ball valve has a simple structure and good sealing performance, but the load of the working medium borne by the ball is all transmitted to the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the ball medium. This structure is widely used in medium and low pressure ball valves.
2. Fixed ball valve
The ball of the ball valve is fixed and does not move after being pressurized. Fixed ball valves are all equipped with floating valve seats. After being pressurized by the medium, the valve seat moves, so that the sealing ring is pressed tightly on the ball to ensure sealing. Bearings are usually installed on the upper and lower shafts of the ball, with small operating torque, 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, an 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, but also 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
The ball of the ball valve is elastic. The ball and the valve seat seal ring are both made of metal materials. The sealing pressure ratio is very large. The pressure of the medium itself cannot meet the sealing requirements, and external force must be applied. This valve is suitable for high-temperature and high-pressure media. The elastic ball is elastic by opening an elastic groove at the lower end of the inner wall of the ball. When closing the channel, the wedge head of the valve stem is used to expand the ball and press it against the valve seat to achieve sealing. Before turning the ball, loosen the wedge head, and the ball will return to its original shape, so that a small gap appears between the ball and the valve seat, which can reduce the friction of the sealing surface and the operating torque.
