Differences and applications of pneumatic ball valves and pneumatic butterfly valves

In the selection of  pneumatic  valves in quarter-turn valves, pneumatic ball valves and Pneumatic Butterfly Valves are two commonly used valves; and Pneumatic Butterfly Valves are two commonly used valves; Imported pneumatic butterfly valves and imported pneumatic ball valves account for 80% of pneumatic valves, so it is necessary to analyze the differences and applications between the two.

In the selection of pneumatic valves, quarter turn valves, Pneumatic Ball Valves, 
Pneumatic ball valve, Pneumatic ball valve, also known as pneumatic switch ball valve, pneumatic regulating ball valve, refers to a ball valve composed of a pneumatic actuator and a ball valve, with a pneumatic actuator to drive the valve switch or adjustment, which can realize the automatic control of the medium switch or adjustment. Pneumatic, flange connection, floating ball straight-through structure form, seat sealing surface material is PTFE, reinforced PTFE plastic (Q641F), metal surfacing cobalt-based (Q641Y), nominal pressure PN16~PN63, valve body material is WCB, CF8, CF8M, alloy steel ball valve. Imported Pneumatic Butterfly Valves (pneumatic regulating butterfly valves, pneumatic single-acting butterfly valves, stainless steel Pneumatic Butterfly Valves) are composed of pneumatic actuators and butterfly valves. The imported pneumatic butterfly valve is composed of a quarter-turn pneumatic actuator and a butterfly valve body, which is easy to operate through the control of a two-position five-way solenoid valve, and can also adjust the parameters of medium flow, temperature, pressure and other parameters with a valve positioner. I the valve fluid resistance is small, the effective flow area is large when fully opened, the opening and closing is fast and labor-saving, the butterfly plate can be opened and closed by rotating 90 degrees, because the butterfly plate on both sides of the rotating shaft is close to equal to the force of the medium, and the torque direction is opposite, so the opening and closing torque is small, and a good seal can be achieved under low pressure. Pneumatic butterfly valve classification: stainless steel pneumatic butterfly valve, hard seal pneumatic butterfly valve, soft seal pneumatic butterfly valve, carbon steel pneumatic butterfly valve. The imported pneumatic butterfly valve is different from the pneumatic ball valve, which is a kind of valve that uses the disc opening and closing parts to reciprocate about 90° to open, close and adjust the fluid channel.

They have various characteristics, advantages and disadvantages, as well as different applications 
1. Characteristics of imported pneumatic ball valves:
Blockage and secretion: When the valve is closed, the valve seat on the upstream and downstream side blocks the liquid, and the stagnant matter in the cavity of the valve body can be secreted through the secretion device. Automatic pressure relief structure: when the pressure of the side cavity is abnormally added, the medium of the middle cavity can automatically relieve the pressure by pushing the valve seat by relying on its own thrust, and then ensure the safety of the valve lift. Reliable sealing of the valve stem: the valve stem is selected with a bottom-mounted structure of the reverse seal, and the sealing force of the reverse seal increases with the increase of the medium pressure, so the reliable sealing of the valve stem can be guaranteed, and the valve stem will not be sprayed out when the valve stem is abnormally pressurized. Fireproof structure: According to the working conditions and the needs of users, the ball valve can be planned as a fireproof structure. Anti-static structure: when operating the valve, due to the friction between the ball and the valve seat, the electrostatic charge will occur and accumulate on the ball, in order to prevent the occurrence of electrostatic sparks, the electrostatic equipment is set on the valve to export the charge accumulated on the ball.

Pneumatic ball valves are mainly used in pipelines for fast shut-off, distribution and changing the flow direction of the medium. Pneumatic ball valve is a new type of valve, which has the following advantages:
　　1. The fluid resistance is small, and its resistance coefficient is equal to that of the pipe section of the same length.
　　2. Large circulation capacity.
　　3. Tight and reliable, the sealing surface material of the ball valve is widely made of plastic, with good sealing, and has been widely used in the vacuum system.
　　4. Easy to operate, fast opening and closing, from full open to full closed, as long as the rotation is 90°, which is convenient for long-distance control.
　　5. It is easy to maintain, the structure of the pneumatic ball valve is simple, the sealing ring is generally movable, and it is more convenient to disassemble and replace.
　　6. When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the erosion of the sealing surface of the valve will not be caused when the medium passes.
　　7. Wide range of application, from small to a few millimeters, as large as several meters, from high vacuum to high pressure can be applied.
　　8. 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, compared with hydraulic and electric, the gas can be discharged directly, which does not pollute the environment and has high safety.
　　9. The fluid can enter the valve body from any direction, that is, there is no inlet and outlet, and it is easy to install and use; Two-way sealing.
10. Compared with the pneumatic butterfly valve, the pneumatic ball valve can achieve a higher pressure, such as the imported pneumatic ball valve of the American Weidun VTON brand, the maximum pressure is 50Mpa, 2500LB, and the pneumatic butterfly valve cannot reach it.
11. The pneumatic ball valve can be made into a V-shaped mouth, which is suitable for controlling high viscosity, fibrous and fine particles. 

The disadvantages are as follows:
　　1. Its adjustment performance is worse than that of globe valves, especially pneumatic valves; 2. Because the most important seat sealing ring material of pneumatic ball valve is PTFE, it is inert to almost all chemicals. However, the physical properties of PTFE, including a high coefficient of expansion, susceptibility to cold flow, and poor thermal conductivity, require that seat seals be designed around these properties. When the sealing material hardens, the reliability of the seal is compromised. Moreover, PTFE has a low temperature resistance rating and can only be used at temperatures less than 180°C. Beyond this temperature, the sealing material will deteriorate. If you want to use it for a long time, it is generally recommended to use it at 120°C;
　　2. Because the most important seat sealing ring material of pneumatic ball valve is PTFE, it is inert to almost all chemicals. However, the physical properties of PTFE, including a high coefficient of expansion, susceptibility to cold flow, and poor thermal conductivity, require that seat seals be designed around these properties. When the sealing material hardens, the reliability of the seal is compromised. Moreover, PTFE has a low temperature resistance rating and can only be used at temperatures less than 180°C. Beyond this temperature, the sealing material will deteriorate. If you want to use it for a long time, it is generally recommended to use it at 120°C;
　　2. Advantages of imported pneumatic butterfly valves:
　　1. It is convenient and fast to open and close, labor-saving, and has low fluid resistance, and can be operated frequently.
　　2. The structure is simple, small in size and light in weight.
　　3. It can transport mud and accumulate the least liquid at the mouth of the pipeline.
　　4. Under low pressure, it can complete outstanding sealing.
　　5. The flow characteristics tend to be straight, and the adjustment performance is good.
6. It can achieve a super large diameter, with a diameter of up to DN3000, which pneumatic ball valves cannot achieve.
7. Under the condition of the same caliber pressure material, the imported pneumatic butterfly valve is more cost-effective, and the price cost will be lower than that of the pneumatic ball valve.

Shortcoming:
　　1. The sealing performance of pneumatic butterfly valve is poor compared with pneumatic ball valve and pneumatic valve, so it is used in places where the sealing requirements are not very high;
　　2. Due to the limitation of the structure and sealing material of the pneumatic butterfly valve, it is not suitable for use in the pipeline system of high temperature and high pressure. The general working temperature is below 300°C, PN40 or below;
　　3. The flow adjustment range of the pneumatic butterfly valve is not large, when the opening reaches 30%, the flow rate reaches nearly 95%; Pneumatic butterfly valves and pneumatic ball valves are not allowed to use valves with bore shrinkage under certain operating conditions.
　　Through the above analysis, users can choose the imported pneumatic valve suitable for the working conditions according to the advantages and disadvantages of pneumatic ball valve and   pneumatic  butterfly valve.