1. Floating ball valve: The ball of a ball valve is floating, and under the action of medium pressure, the ball can produce a certain displacement and tightly press on the sealing surface of the outlet end, ensuring the sealing of the outlet end.
(Note: The floating ball valve has a simple structure and good sealing performance, but the ball bears all the load of the working medium and is 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. When subjected to high pressure impact, the ball may deviate. This structure is generally used for medium and low pressure ball valves.)
2. Fixed ball valve: The ball of a ball valve is fixed and does not move under pressure. Fixed ball valves are equipped with floating valve seats, which move when subjected to medium pressure, causing the sealing ring to tightly press against the ball to ensure sealing.
(1) Usually, bearings are installed on the upper and lower shafts of the ball, with small operating torque, suitable for high-pressure and large-diameter valves.
(2) In order to reduce the operating torque of ball valves and increase the reliability of sealing, lubricating oil is used to form a layer of oil film, which enhances sealing performance and reduces operating torque, making it more suitable for high-pressure large-diameter ball valves.
3. Elastic ball valve: The ball of a ball valve is elastic. Both the ball and valve seat sealing rings are made of metal materials, with a high sealing pressure ratio. The pressure of the medium itself cannot meet the sealing requirements, and external forces must be applied. This valve is suitable for high-temperature and high-pressure media.
An elastic sphere is achieved by opening an elastic groove at the lower end of the inner wall of the sphere. When closing the channel, use the wedge-shaped head of the valve stem to expand the ball and compress the valve seat to achieve sealing. Before rotating the ball, loosen the wedge head first, and the ball will return to its original shape, creating a small gap between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface
