Pneumatic butterfly valve working principle

Pneumatic disc valves, also known as butterfly valves, operate by rotating a circular disc that is attached to the valve body. This rotation allows the valve to open and close, making it primarily suitable for shut-off applications. However, these valves can also be designed for flow regulation or stepwise control. Their use in low-pressure pipelines with medium to large diameters is becoming increasingly common due to their efficiency and reliability.

One of the main advantages of disc valves is their simple construction, compact size, light weight, and cost-effectiveness. These features are especially beneficial for pneumatic models, which are often used in hard-to-reach areas like high-altitude tunnels. They can be easily controlled using a two-position five-way solenoid valve. Additionally, they offer minimal fluid resistance. When fully open, large and medium-sized pneumatic disc valves allow for a large flow area, enabling quick and effortless operation. A 90-degree rotation of the disc is sufficient to open or close the valve. Since the forces acting on both sides of the disc are nearly balanced, the torque required for opening and closing is small, allowing for excellent sealing performance under low pressure.

The sealing materials used in disc valves include nitrile rubber, fluororubber, edible rubber, and PTFE lining. This ensures good sealing performance. Hard-seal disc valves combine metal sheets with elastic materials, offering the benefits of both a rigid metal seal and an elastic seal. This hybrid design provides excellent sealing, even at low temperatures.

The working principle of a butterfly valve involves a disc mounted within the pipe’s diameter. As the disc rotates around the axis inside the cylindrical body, it controls the flow. The rotation angle typically ranges from 0° to 90°, with full opening occurring at 90°. This mechanism makes it ideal for various industrial applications.

Butterfly valves are known for their simple structure, compact size, and lightweight design. They consist of only a few components, making them easy to install and maintain. A 90-degree rotation allows for fast opening and closing, and their operation is straightforward. Electrically actuated versions provide excellent flow control characteristics. When fully open, the disc acts as the only resistance, resulting in minimal pressure drop across the valve, which enhances its flow control performance.

There are two main types of sealing in butterfly valves: spring-loaded seals and metal seals. Elastomeric seals can be either mounted directly on the valve body or attached to the edge of the disc. While metal-sealed valves tend to last longer, they may not seal completely. On the other hand, elastomeric seals have temperature limitations but offer better flexibility in certain conditions.

When selecting a butterfly valve for flow control, it's essential to choose the right size and type based on the application. Butterfly valves are particularly well-suited for large-diameter installations. They are widely used in industries such as oil and gas, chemicals, water treatment, and power generation, including cooling systems in thermal power plants.

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