Difference between Fixed Ball Valve and Floating Ball Valve

Ball valve is evolved by cock valve. It has the same rotate 90 degrees mention action, and the difference is that its cock body is sphere, and has circular through hole or channel through its axis. Ball valve only needs to rotate 90 degrees with the operation and small rotation moment can shut tight. Completely equal body cavity for medium provides very small resistance and straight-flow passage. 

Recently, ball valves are designed to make it has the throttle and control flow with. The main characteristics of ball valve is that its structure is compact, it is easy to operate and maintain, and it can be applicable to some working medium such as water, solvent, acid and gas; it is also suitable for poor working conditions of medium, such as oxygen, hydrogen peroxide, methane and ethylene, etc. Ball valve body can be whole or combined type.

There are mainly two types of ball valve– fixed ball valve and floating ball valve, so what’s the difference between the two?

The sphere of floating ball valves is floating, under the action of medium pressure, the ball physically produces certain displacement and presses in the outlet seals, in order to ensure outlet seal, and it belongs to the single forced seal.

Fixed ball valve is fixed, has a sphere with the fixed shaft, the fixed shaft are connected together by the two sections with the ball bearing; when it is closed, and together with the function of the medium pressure, the ball will not produce displacement. Therefore, in the design of this kind of product, there must be enough pre-stressing force between the two seals so as to guarantee leakproofness. It belongs to the double forced seal.

The design of floating ball valve should consider whether the seal material can withstand sphere medium action load. Because the load when sphere under medium are all passed to outlet seals, therefore, the floating ball structure is widely used in low pressure ball valve. In addition, the design should also consider that large diameter ball valve needs bigger moment during operation process.

As for the fixed ball valve, there are shafts connected together with the ball, the upper and lower shaft is equipped with rolling bearings or sliding bearings, in order to reduce the open and close when the journal of the frictional force, and to reduce the operating torque. Therefore, the fixed ball valve is suitable for high pressure and large diameter valves.