Ball valve is evolved from plug valve. It has the same 90 degree rotation lifting action, the difference is that the plug body is a sphere, with a circular through-hole or channel through its axis. The ratio between the sphere and the passage port should be such that when the sphere rotates 90 degrees, the sphere should be present at the inlet and outlet, so as to cut off the flow.
The ball valve can be closed tightly only with 90 degree rotation operation and small rotation torque. The completely equal inner cavity of the valve body provides a small resistance and straight passage for the medium. It is generally believed that the ball valve is the most suitable for opening and closing directly, but in recent development, the ball valve has been designed to throttle and control the flow. The main features of ball valve are compact structure, easy operation and maintenance, suitable for general working media such as water, solvent, acid and natural gas, and also suitable for media with poor working conditions, such as oxygen, hydrogen peroxide, methane and ethylene. The ball valve body can be integral or combined.
Working principle and practical function of ball valve
The working principle of ball valve is to make the valve unblocked or blocked by rotating the valve. The ball valve has the advantages of light switch, small volume, large caliber, reliable sealing, simple structure and convenient maintenance. The sealing surface and spherical surface are often in closed state and are not easy to be eroded by medium, so it is widely used in various industries.
Ball valve and plug valve belong to the same type of valve, only its closing part is a ball, and the ball rotates around the center line of the valve body to open and close a valve.
Ball valve is mainly used to cut off, distribute and change the flow direction of medium in pipeline. Ball valve is a new type of valve widely used in recent years. It has the following advantages:
1. The fluid resistance is small, and its resistance coefficient is equal to that of the same length of pipe section.
2. Simple structure, small volume and light weight.
3. It is tight and reliable. At present, the sealing surface material of ball valve is widely used in plastic, with good sealing performance, and also widely used in vacuum system.
4. It is easy to operate and fast to open and close. It only needs to rotate 90 ° from full open to full close, which is convenient for remote control.
5. The maintenance is convenient, the ball valve structure is simple, the sealing ring is generally movable, and the disassembly and replacement are relatively convenient.
6. When the valve is fully open or closed, the sealing surface of the ball and the valve seat shall be isolated from the medium. When the medium passes through, the corrosion of the valve sealing surface will not be caused.
7. It has a wide range of applications, ranging from small diameter to several millimeters and large diameter to several meters, from high vacuum to high pressure.
Ball valve has been widely used in petroleum, chemical industry, power generation, paper making, atomic energy, aviation, rocket and other departments, as well as in people's daily life