The ball valve evolved from the plug valve. It has the same rotating 90 degree lifting action, the difference is that the plug body is a sphere with a circular through hole or passage through its axis. The ratio of the sphere and the passage opening should be such that when the ball is rotated 90 degrees, it should all present a spherical surface at the inlet and outlet, thus intercepting the flow.

The ball valve needs to be closed tightly with only a 90 degree rotation operation and a very small turning torque. Completely equal valve body cavity for the medium to provide a very small resistance, straight through the flow path. Usually considered to be the most suitable for the direct use of the ball valve, but recent developments have been designed to make the ball valve has throttling and flow control purposes. The main feature of the ball valve is its own compact structure, easy to operate and maintain, suitable for water, solvents, acids and natural gas and other general working media, but also for harsh working conditions of the media, such as oxygen, hydrogen peroxide, methane and ethylene. The ball valve body can be integral or combined.

The working principle of the ball valve is to rotate the valve love to make the valve open or closed. Ball valve switch lightweight, small size, can be made into a large calibre, reliable sealing, simple structure, easy maintenance, sealing surface and the ball surface is often in the closed state, is not easy to be eroded by the medium, in various industries have been widely used.
Ball valves and plug valves are the same type of valve, only its closing member is a sphere, the sphere rotates around the centre line of the valve body to achieve the opening and closing of a valve.
Ball valve in the pipeline is mainly used to do cut off, distribution and change the direction of flow of media. Ball valve is a new type of valve widely used in recent years, it has the following advantages:

1. small fluid resistance, its resistance coefficient is equal to the same length of the pipe section.

2. simple structure, small size, light weight.

3. compact and reliable, the current ball valve sealing surface materials are widely used in plastics, good sealing, in the vacuum system has been widely used.

4. easy to operate, open and close quickly, from fully open to fully closed as long as the rotation of 90 °, easy to control from a distance.

5. Convenient maintenance, ball valve structure is simple, the sealing ring is generally active, disassembly and replacement are relatively convenient.

6. in fully open or fully closed, the ball and the sealing surface of the valve seat and the media isolation, the media through, will not cause erosion of the valve sealing surface.

7. Wide range of applications, from small diameter to a few millimetres, up to several metres, from high vacuum to high pressure can be applied.

Ball valves have been widely used in petroleum, chemical, power generation, paper, atomic energy, aviation, rockets and other sectors, as well as people's daily life.