Ball valves are quarter turn valve and in the path of fluid a ball are placed and therefore it is called ball valve. There is a straight hole in the ball. As the hole of the ball is placed in same direction as the flow of fluid, the fluids get released and when the hole is at 90 degree position the fluid path is blocked.
These type of sanitary valves are defined as per their ball and hole sizes. There are three different kinds of valves, which are as follows:
- Floating ball valve
Since the sphere-shaped ball of the valve floats, it has been so named and under the influence of medium pressure, certain displacement is produced by the sphere. It also gets pressed tightly to sealing surface at its opening, so that the outlet gets sealed. The structure of this floating valve is quite simple and having good sealing but working medium’s load is sustained by this sphere, which is completely passed on the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material can sustain the sphere medium’s working load. This structure is generally used in low or medium pressure valves.
- Fixed ball valve
Here the ball or the sphere of the valve remains fixed and after being pressured it does not move. There are floating valve that seats with all fixed ball valves. The valve seat moves under medium pressure and as a result, sealing ring is tightly pressed on the sphere to make sure the sealing is done. Usually, on the sphere’s lower and upper shafts, the bearings are installed. There is a small operating stroke, which is suitable for valves of large diameter and high pressure.
If you want to increase the reliability of sealing and reduce the operating torque of this ball valve, you will find an oil sealing ball valve used nowadays. Between the sealing surfaces, special types of lubricant is injected so that a layer of oil film gets created. Due to this reason, sealing is enhanced and at the same time operating torque reduces. This type of ball valve is more suitable for large diameter and high-pressure type of valves.
- Elastic ball valve
In this case the sphere of the valve is elastic. Both sealing ring as well as sphere is made of metals. Sealing pressure of these valves is very high. If you rely on the medium’s pressure then it is not possible to meet the requirement of sealing and hence external force need to be applied. This type of valve is suitable for high or medium high pressure applications.