Pneumatic butterfly valve is a kind of valve that uses disc-type opening and closing parts to reciprocate to rotate about 90 ° to open, close and adjust the fluid channel. The pneumatic ball valve uses the ball to rotate 90 ° around the axis of the valve stem to achieve the purpose of opening and closing.
feature:
1. Pneumatic ball valves are mainly used to cut off, distribute and change the direction of medium flow on the pipeline. Pneumatic ball valves designed as V-shaped openings also have a good flow adjustment function. When the valve is closed, the valve seat on the upstream and downstream sides blocks the liquid, and the accumulation in the cavity of the valve body can be secreted by the secretion device. When the pressure in the side chamber is abnormally added, the medium medium can automatically release the pressure by pushing the valve seat based on its own thrust, and then ensure the safety of the valve. The stem adopts a bottom-mounted structure with an inverted seal. The sealing force of the inverted seal increases with the increase of the medium pressure, so it can ensure the reliable sealing of the stem, and when the stem is abnormally boosted, the stem will not eject . According to the working conditions and the needs of users, the ball valve can be designed as a fireproof structure. When operating the valve, due to the friction between the ball and the valve seat, cattle electrostatic charge will occur and accumulate on the ball. In order to prevent the occurrence of static sparks, an electrostatic device is specially installed on the valve to discharge the charge accumulated on the ball.
2. The circular butterfly plate with the pneumatic butterfly valve rolling along with the valve is used for opening and closing. The pneumatic valve that completes the activation action is mainly used as a shut-off valve. According to the structural characteristics of the pneumatic butterfly valve, it can also be planned to have a scheduling or segment valve and scheduling function. Nowadays, the application of butterfly valves in low-pressure large-medium-caliber pipelines is continuously added. In fact, many devices have pneumatic butterfly valves, especially pipes, but we must not underestimate it. However, many people have heard of pneumatic butterfly valves, but they do not understand their advantages and disadvantages. But it doesn't matter that the editor will introduce us the advantages and disadvantages of pneumatic butterfly valves.
advantage:
1. The fluid resistance of the pneumatic ball valve is small, and its resistance coefficient is equal to that of the pipe section of the same length. Simple structure, small size and light weight. It is tight and reliable. The sealing surface material of ball valve is widely used plastic and has good sealing performance. It has also been widely used in vacuum system. It is easy to operate and quick to open and close. It only needs to rotate 90 ° from fully open to fully closed to facilitate remote control. The maintenance is convenient, the structure of the pneumatic ball valve is simple, the sealing ring is generally movable, and the disassembly and replacement are more convenient. When fully open or fully closed, the sealing surfaces of the ball and the valve seat are isolated from the medium. When the medium passes through, it will not cause corrosion of the valve sealing surface. It has a wide range of applications, from small diameters to a few millimeters to a few meters, from high vacuum to high pressure. Because the power source of the pneumatic ball valve is gas, it is generally 0, 2-0, 8MPa pressure, which is relatively safe. If the pneumatic ball valve leaks, the gas can be directly discharged compared to the hydraulic and electric, which has no pollution to the environment and has high safety.
2. Pneumatic butterfly valve opening and closing is convenient, fast, labor saving, low fluid resistance, and can be operated frequently. The structure is simple, small in size and light in weight. It can transport mud and has little liquid accumulation in the pipe mouth. Under low pressure, it can achieve excellent sealing. Conditioning performance is good.
Disadvantages:
1. The adjustment performance of the pneumatic ball valve is worse than that of the globe valve; because the main seat sealing material of the pneumatic ball valve is PTFE, it is inert to almost all chemical substances. However, the physical characteristics of PTFE, including the higher coefficient of expansion, sensitivity to cold flow and poor thermal conductivity, require that the design of the valve seat seal must be carried out around these characteristics. When the sealing material becomes hard, the reliability of the seal is destroyed. Moreover, PTFE has a low temperature resistance level and can only be used at less than 180 ° C. Above this temperature, the sealing material will age. If you want to use it for a long time, it is generally recommended to use it at 120 ℃;
Second, the sealing performance of pneumatic butterfly valves is poor compared to pneumatic ball valves and pneumatic valves, so it is not used in places where the sealing requirements are very high; due to the limitations of the structure and sealing materials of pneumatic butterfly valves, it is not suitable for high temperature and high pressure pipeline systems . The general working temperature is below 300 ℃, below PN40; the flow adjustment range of the pneumatic butterfly valve is not large, when the opening reaches 30%, the flow reaches more than 95%;
Pneumatic butterfly valves and pneumatic ball valves are not allowed to use valves with reduced diameters under certain working conditions. This aspect is to reduce the resistance loss of the pipeline, on the other hand, it is to avoid obstacles caused by mechanical shrinkage of the pipeline after the diameter shrinks.
