Structure and type of fixed sealing ball valve


Floating ball valve with fixed sealing seat. The struct […]

Floating ball valve with fixed sealing seat. The structure of this fixed sealing ball valve is shown in Figure 2-2. Its main structure is a sealing ball (floating ball), a fixed sealing seat (two), a valve cover, a valve stem, a handle and a packing sealing device. A fixed sealing valve seat made of two fluoroplastics is installed in the valve body, and the floating ball sphere is clamped between the two valve seats. In order to improve the sealing performance of the fixed sealing ball valve, the ball has higher manufacturing precision and smaller surface roughness. With the rotation of the handle and the valve stem, the ball can be rotated to achieve the switching purpose.
The type of fixed ball valve can be divided into two types: the sealing seat in front of the ball and the sealing seat behind the ball, depending on the size of the tightness of the seal at work. Commonly used ball valves are: electric ball valve and pneumatic ball valve.
Types of fixed seal ball valves 1 Fixed ball valves with seal seats in front of the ball. The structure of this fixed ball valve is shown in Figure 2-4. The principle of operation is that the ball with the shaft can rotate freely in two sliding or rolling bearings. The sealing seat is mounted on a movable sleeve that is sealed in the body with a round rubber seal. Both the left and right sealing seat and the sleeve are pre-pressed on the ball by the spring set. The valve seat on the left inlet end presses the ball against the pressure acting on the annular surface of the inner diameter d and the outer diameter Di when the ball is closed, thereby achieving the sealing effect, and the sealing seat at the outlet end does not seal.
Types of fixed seal ball valves 2 Sealed ball valves with a sealed seat behind the ball. The structure of the fixed sealing ball valve is shown in Figure 2-5. Compared with the ball valve sealed in front of the ball, the structural difference is that the sealing diameter D2 on the movable sleeve is smaller than the average diameter of the sealing. In order to ensure this condition, The inner diameter di of the valve seat should be greater than the diameter d of the ball. When the fixed ball valve is pressurized in the closed state, the valve seat at the inlet end does not seal because the medium pressure does not cause the inlet sealing seat to press against the ball but the valve seat leaves the ball. On the contrary, due to the effect of the medium pressure, the ball rear sealing seat presses the ball, which ensures the complete sealing of the ball.