The opening and closing component of a ball valve is a spherical body with a circular channel that rotates around an axis perpendicular to the channel. The spherical body rotates with the valve stem to achieve the purpose of opening and closing the channel. Ball valves can be tightly closed with only a 90 degree rotation and a small rotational torque. According to the working conditions, different driving devices can be assembled to form ball valves with various control methods, such as electric ball valves, pneumatic ball valves, hydraulic ball valves, and so on.

I. According to structural form, it can be classified as follows

1. Floating ball valve

The ball of a ball valve is floating, and under the pressure of the medium, the ball can produce a certain displacement and press tightly against the sealing surface at the outlet end, ensuring the sealing of the outlet end.

The structure of a floating ball valve is simple and has good sealing performance, but the load borne by the working medium on the ball is all transferred 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 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 seats, which move when subjected to medium pressure, causing the sealing ring to press tightly against the ball to ensure sealing. Usually, bearings are installed on the upper and lower shafts of the sphere, with a small operating torque, suitable for high-pressure and large-diameter valves.

In order to reduce the operating torque of ball valves and increase the availability of seals, oil sealed ball valves have emerged in recent years. They inject special lubricating oil between the sealing surfaces to form an oil film, which enhances sealing performance and reduces operating torque, making them more suitable for high-pressure and large-diameter ball valves.

3. Elastic ball valve

The ball of a ball valve is elastic. The ball and valve seat sealing ring are both made of metal materials, and the sealing pressure ratio is very high. According to the pressure of the medium itself, it cannot meet the sealing requirements and external force must be applied. This type of valve is suitable for high temperature and high pressure media.

An elastic sphere is obtained by creating an elastic groove at the lower end of its inner wall. When closing the channel, use the wedge-shaped head of the valve stem to expand the ball and press it against the valve seat to achieve sealing. Release the wedge-shaped head before rotating the sphere, and the sphere will return to its original shape, creating a small gap between the sphere and the valve seat, which can reduce friction and operating torque on the sealing surface.

4. Other classifications

According to pressure: high pressure ball valve, medium pressure ball valve, low pressure ball valve

By channel type: full bore ball valve, reduced bore ball valve

By channel position: straight through, three-way, right angle

According to temperature: high temperature ball valve, normal temperature ball valve, low temperature ball valve, ultra-low temperature ball valve

According to sealing form: soft seal ball valve, hard seal ball valve

Assemble by valve stem: top mounted ball valve, side mounted ball valve

According to the connection form: flange ball valve, welded ball valve, threaded connection ball valve, clamp ball valve

By driving mode: manual ball valve, automatic control ball valve (pneumatic ball valve, electric ball valve, hydraulic ball valve)

By caliber size: super large caliber ball valve, large caliber ball valve, medium caliber ball valve, small caliber ball valve.

II. Working Principle 

When the ball valve rotates 90 degrees, it should appear spherical at both the inlet and outlet to close the valve and cut off the flow of the medium.

When the ball valve rotates 90 degrees, the ball ports should be fully present at the inlet and outlet, thereby opening the flow and having almost no flow resistance.

III. Structural Principles 

1. Ball valves are not limited by installation direction, and the flow direction of the medium can be arbitrary. Low fluid resistance, full bore ball valves have almost no flow resistance.

2. Ball valves have a simple structure, relatively small volume, light weight, and are easy to maintain.

3. Tight and reliable. It has two sealing surfaces, and currently, various plastics are widely used as sealing surface materials for ball valves, which have good sealing performance and can achieve complete sealing. It has also been widely used in vacuum systems.

4. Ball valves are suitable for frequent operation, with quick and easy opening and closing. Easy to operate, quick opening and closing, only need to rotate 90 ° from fully open to fully closed, making it convenient for remote control.

5. Easy maintenance, simple ball valve structure, and generally movable sealing rings make disassembly and replacement relatively convenient.

6. The ball valve has good sealing performance. When fully open or fully closed, the sealing surfaces of the ball and valve seat are isolated from the medium, and when the medium passes through, it will not cause erosion of the valve sealing surface.

7. It has a wide range of applications, with diameters ranging from a few millimeters to several meters, and can be used from high vacuum to high pressure.

Due to the wiping property of ball valves during opening and closing, they can be used in media with suspended solid particles.

9. Ball valves have low fluid resistance, no vibration, and low noise.

Iv. Function 

The opening and closing component of a ball valve is a circular ball with holes, which uses the ball core to rotate back and forth 0-90 ° around the axis of the valve stem to achieve the purpose of opening or closing the valve. Ball valves have many functions and are generally used to cut off or regulate media in pipelines. Among them, three-way ball valves can flexibly cut off, distribute, and change the flow direction of media. The sealing surface of ball valves is usually in a closed state with the spherical surface, so it is not easily eroded by the medium, easy to operate, simple and compact in structure, and can be used in working conditions with water, natural gas, acid, solvents, etc.

V. Usage 

Ball valves can generally be divided into three categories based on their structural form: floating ball valves, fixed ball valves, and elastic ball valves. According to their sealing performance, they are divided into hard sealed ball valves and soft sealed ball valves. Among them, soft sealed ball valves have better sealing performance and can achieve zero leakage. They are generally used in pipelines with corrosive media at room temperature and pressure. Hard sealed ball valves can not only be used in pipelines at room temperature and pressure, but also in pipelines with low temperature, low pressure, and high temperature and high pressure. Ball valve and its working principle, function and application.