The difference between ball valve and plug valve

The ball valve evolved from the plug valve. The ball valve has a line seal and the plug valve has a surface seal. The plug valve is not as good as the ball valve in terms of high temperature and high pressure resistance. The plug valve has a simple structure, rapid opening and closing, and low fluid resistance. It is suitable for regular operations. It opens and closes quickly, is light, has a simple structure, is relatively small in size, is light in weight, and is easy to maintain. More importantly, it is much cheaper than a ball valve. In terms of application, as long as it is not used in high temperature and high pressure, plug valves will basically be chosen. For example, many plug valves will be used in coal chemical industries such as the production of acetic acid and acetic anhydride. Ball valves can achieve full diameter, but plug valves cannot. The channel is usually rectangular or trapezoidal, while ball valves are O-shaped. Plug valves are also suitable for high temperatures and high pressures, but they must use metal seals. Since their sealing surfaces are face seals, the torque is much larger than that of ball valves. In addition, in order to reduce friction on the sealing surface, metal plug valves Usually, an oil filling port is set outside the valve, and a lubricating groove is set inside to reduce friction and provide sealing life. Another advantage of the plug valve is that the gap between the valve core and the valve body is much smaller than that of the ball valve, which can reduce medium accumulation and overpressure. In terms of price comparison, the overall price of the plug valve with actuator is more expensive than that of the ball valve.

Plug valve (xuansaifa) Ball valve Plug valve uses a plug body with a through hole as the opening and closing part. The plug body rotates with the valve stem to achieve opening and closing actions. Small unpacked plug valves are also called "cock". The plug body of the plug valve is mostly a cone (there are also cylinders), which cooperates with the conical hole surface of the valve body to form a sealing pair. Plug valve is the earliest type of valve with simple structure, fast opening and closing, and low fluid resistance. Ordinary plug valves are sealed by direct contact between the precision-machined metal plug body and the valve body, so the sealing performance is poor, the opening and closing force is large, and it is easy to wear. It can usually only be used in low (not higher than 1 MPa) and small diameter (less than 100 mm) situations. In order to expand the application range of plug valves, many new structures have been developed. Oil-lubricated plug valves are the most important type (see picture). Special grease is injected from the top of the plug body between the taper hole of the valve body and the plug body to form an oil film to reduce the opening and closing torque and improve sealing and service life. Its working pressure can reach 64 MPa, its maximum working temperature can reach 325°C, and its maximum diameter can reach 600 mm. 　　Plug valve passages come in many forms. The common straight-through type is mainly used to cut off fluid. Three-way and four-way plug valves are suitable for fluid reversing. The opening and closing part of the plug valve is a cylinder with a hole, which rotates around an axis perpendicular to the channel to achieve the purpose of opening and closing the channel. Plug valves are mainly used to open and close pipelines and equipment media. 　　The main advantages of plug valves are as follows: 　　1. Suitable for frequent operations, opening and closing quickly and easily. 　　2. Small fluid resistance. 　　3. Simple structure, relatively small size, light weight and easy to maintain. 　　4. Good sealing performance. 5. It is not restricted by the installation direction, and the flow direction of the medium can be arbitrary. 　　6. No vibration and low noise. 　　Plug valves can be divided into four types according to their structural forms: tight-fitting plug valves, self-sealing plug valves, packing plug valves and oil-filled plug valves. According to the channel form, it can be divided into three types: straight-through type, three-way type and four-way type. Ball valves evolved from plug valves. It has the same lifting action of rotating 90 degrees, but the difference is that the cock body is a sphere with a circular through hole or channel passing through its axis. The ratio of the spherical surface to the channel opening should be such that when the ball is rotated 90 degrees, all spherical surfaces should appear at the inlet and outlet, thus cutting off the flow. Has the following advantages: 　　1． The fluid resistance is small, and its resistance coefficient is equal to that of a pipe section of the same length. 　　2. It has simple structure, small size and light weight. 　　3． Tight and reliable, plastic is widely used as the sealing surface material of ball valves at present, with good sealing performance, and has also been widely used in vacuum systems. 　　4． It is easy to operate and opens and closes quickly. It only needs to be rotated 90° from fully open to fully closed, which is convenient for long-distance control. 　　5. It is easy to maintain. The ball valve has a simple structure and the sealing ring is generally movable, making it easy to disassemble and replace. 　　6. When fully open or fully closed, the sealing surfaces of the ball and valve seat are isolated from the medium. When the medium passes, 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 applied from high vacuum to high pressure. 　　Ball valves have been widely used in petroleum, chemical industry, power generation, papermaking, atomic energy, aviation, rocket and other departments, as well as in people's daily life

The second floor seems to be a bit contradictory. :lol This post was last edited by Wa Duotou on 2009-3-17 22:20 ]

It seems that compared to plug valves, ball valves are used in high-pressure and high-temperature applications. Others seem to be similar, right?

I don’t know if there are any pictures, but I’ll send them to you so that you can have a deeper understanding.

Plug valves have an important feature: there is no dead space in the valve cavity, so they are often used in the food industry.

The main difference is that the temperature difference between the two is relatively large, and the ball valve has a wider range of uses.