What is a ball valve?

Update:28-10-2020
Summary:

Convenient operation, rapid opening and closing, from b […]

Convenient operation, rapid opening and closing, from bai fully open to fully closed as long as du rotates 90°, which is convenient for remote control. 3. Convenient maintenance, simple structure of ball valve dao, generally movable sealing ring, easy to disassemble and replace. 4. Simple structure, small size and light weight. 5. It is tight and reliable. At present, the sealing surface material of the ball valve is widely used in plastics with good sealing performance, and it has also been widely used in the vacuum system. 6. When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the medium will not cause erosion of the valve sealing surface when the medium passes.

 

 

Ball valves have been widely used in petroleum, chemical, power generation, papermaking, atomic energy, aviation, rockets and other sectors, as well as people's daily lives. Ball valvesUPVC Strong Union Flanged Ball Valve can be divided into structural forms: 1. Forged steel fixed ball valve The ball of the ball valve is fixed and does not move after being pressed. The fixed ball valve has a floating valve seat. After receiving the pressure of the medium, the valve seat will move, so that the sealing ring is pressed tightly on the ball to ensure sealing. Bearings are usually installed on the upper and lower shafts of the ball, and the operating torque is small, which is suitable for high pressure and large diameter valves. In order to reduce the operating torque of the ball valve and increase the reliability of the seal, oil-sealed ball valves have appeared in recent years. Special lubricating oil is injected between the sealing surfaces to form an oil film, which enhances the sealing performance and reduces the operating torque. , It is more suitable for high pressure and large diameter ball valves. 2. Elastic ball valve The ball of the ball valve is elastic. Both the ball and the valve seat sealing ring are made of metal materials, and the sealing specific pressure is very large. The pressure of the medium itself cannot meet the sealing requirements, and external force must be applied. This valve is suitable for high temperature and high pressure media. The elastic sphere is made by opening an elastic groove on the lower end of the inner wall of the sphere to obtain elasticity. When closing the passage, use the wedge-shaped head of the valve stem to expand the ball and press the valve seat to seal. Loosen the wedge-shaped head before rotating the ball, and the ball will return to its original shape, so that there is a small gap between the ball and the valve seat, which can reduce the friction of the sealing surface and the operating torque. Ball valves can be divided into straight-through type, three-way type and right-angle type according to their channel position.

The three-way four-sealed ball valve is used to distribute the medium and change the flow direction of the medium. 3. Hard-sealed floating ball valve The ball of the ball valve is floating. Under the action of the medium pressure, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet end to ensure that the outlet end is sealed. The floating ball valve has a simple structure and good sealing performance, but the load of the ball bearing the working medium is all transmitted to the outlet sealing ring, so it is necessary to consider whether the sealing ring material can withstand the working load of the spherical medium. This structure is widely used in medium and low pressure ball valves. Ball valves are widely used in irrigation systems, mainly at the inlet of branch pipes. The ball valve has a simple structure, small volume, and low resistance to water flow. The disadvantage is that it opens or closes too quickly, which will produce water hammer in the pipeline (the pressure will increase when the water flow speed in the pipeline changes suddenly). Therefore, it is not appropriate to use ball valves on the main pipes, and can be used for flushing on the stem and branch pipes or at their ends. The flushing effect is good. Ball valves are divided into O-shaped ball valves and V-shaped ball valves. The O-type ball valve adopts a floating structure, the ball core is a precision casting, the surface is plated with hard chromium, and the valve seat is made of reinforced polytetrafluoroethylene. The flow passage is the same as the pipe diameter, the flow capacity is very large, the flow resistance is very small, and there is no Leakage, generally used as on-off valve, especially suitable for high-viscosity, fiber-containing, granular media; V-shaped ball valve adopts a fixed structure, with a V-shaped cut on the ball core, which can achieve proportional adjustment, and the flow characteristic is approximately equal percentage. According to different process equipment, high-pressure internal thread ball valve and forged steel three-piece hard-sealed ball valve can be composed, of which high-pressure internal thread ball valve must be equipped with a valve positioner to achieve proportional adjustment, and forged steel three-piece hard-sealed ball valve must achieve proportional adjustment Must choose electronic electric actuator or equipped with servo amplifier, etc.

 

The male threaded ball valve butt-welded ball valve is a valve that uses a sphere with a circular channel as the opening and closing part, and the sphere rotates with the valve stem to realize the opening and closing action. The opening and closing part of the external thread ball valve butt welding ball valve is a holed sphere, which rotates around the axis perpendicular to the channel to achieve the purpose of opening and closing the channel. Ball valves are mainly used to open and close pipelines and equipment media. (It can reduce the resistance when opening and closing the pipeline and prolong the use time.) O-type ball valves have more descriptions of fixed structure ball cores that use forgings: Ball valves evolved from plugs. The opening and closing part is a sphere, and the sphere is rotated 90o around the axis of the valve stem to achieve the purpose of opening and closing. The ball valve is mainly used to cut off, distribute and change the direction of the medium flow in the pipeline. The ball valve designed as a V-shaped opening also has a good flow adjustment function. The ball valve is not only simple in structure, good in sealing performance, but also small in size, light in weight, low in material consumption, small in installation size, and small in driving torque within a certain nominal passage range. It is simple to operate and easy to achieve rapid opening and closing. One of the fastest growing valve varieties in the past ten years. Especially in developed countries such as the United States, Germany, France, Italy, Spain, and Britain, the use of ball valves is very extensive, and the variety and quantity of use continue to expand, and the use of high temperature, high pressure, large mouth, high sealing, long life , Excellent adjustment performance and multifunctional development of a valve, its reliability and other performance indicators have reached a higher level, and have partially replaced gate valves, globe valves, and throttle valves. With the advancement of ball valve technology, in the foreseeable short time, there will be a wider range of applications in oil and gas pipelines, oil refining crackers, and the nuclear industry. In addition, ball valves will also become one of the leading valve types in large and medium-sized calibers and medium and low pressure fields in other industries.