1. Basic structure and working principle of butterfly valve
The main feature of the butterfly valve is to adjust the flow of the fluid through a circular butterfly plate. The basic structure of the butterfly valve includes a valve body, a valve stem, a butterfly plate and a sealing ring. The butterfly plate is installed in the middle of the pipeline and controls the flow of the fluid by rotation. The switch operation is usually completed with a 90° rotation.
The working principle of the butterfly valve is relatively simple. The opening and closing of the valve is controlled by the rotation of the butterfly plate, and the rotation angle determines the size of the flow. It is suitable for large-caliber and low-pressure occasions, especially in flow regulation and fluid isolation.
2. Key factors for purchasing butterfly valves
When purchasing butterfly valves, the following key factors need to be considered:
1. Fluid properties
The type, temperature, pressure and corrosiveness of the fluid are one of the most important considerations when purchasing butterfly valves. Different fluids require different valve materials and sealing methods. For example, acidic, alkaline or high-temperature fluids require corrosion-resistant and high-temperature resistant butterfly valves; for flammable and explosive gas media, special attention should be paid to sealing performance.
2. Working pressure and temperature
The working pressure and temperature range of butterfly valves directly affect their material selection. The working pressure of butterfly valves is usually low, but if used in high-pressure systems, butterfly valves suitable for high-pressure environments must be selected. At the same time, high-temperature fluids require the use of high-temperature resistant materials such as stainless steel or special alloys.
3. Valve body material
The valve body of a butterfly valve is usually made of cast iron, carbon steel, stainless steel or alloy steel. When purchasing, choose the appropriate valve body material according to the working environment:
- Cast iron butterfly valve: suitable for general water treatment and low-pressure occasions
- Carbon steel butterfly valve: Suitable for general gas or liquid control systems, with poor corrosion resistance.
- Stainless steel butterfly valve: Suitable for highly corrosive media, with good corrosion resistance and high temperature resistance.
- Alloy steel butterfly valve: Suitable for high temperature, high pressure or special chemical media environment.
4. Sealing method
There are two sealing methods for butterfly valves: soft sealing and hard sealing. Soft-sealed butterfly valves use rubber, polytetrafluoroethylene (PTFE) and other materials for sealing, which are suitable for low-pressure occasions and have good sealing; hard-sealed butterfly valves use metal materials as sealing rings, which are suitable for high temperature, high pressure or highly corrosive working environments.
5. Diameter and installation method
Butterfly valves are suitable for large-diameter pipelines, so when purchasing, choose the corresponding butterfly valve according to the size of the pipeline. Common butterfly valve connection methods include flange connection, clamp connection and threaded connection. For large-diameter pipelines, flange connection is generally selected; for small-diameter pipelines, threaded or clamp connection can be selected.
6. Drive mode
The drive modes of butterfly valves include manual, electric, pneumatic and hydraulic. Choosing the right drive mode can improve the operating efficiency and safety of the system.
- Manual drive: Suitable for occasions with low operating frequency and low cost.
- Electric drive: Suitable for systems that require automated operation and can be remotely controlled.
- Pneumatic drive: Suitable for fast opening and closing and frequent operation, and can achieve efficient and fast switch control.
- Hydraulic drive: Suitable for occasions with high pressure or higher operating force.
7. Flow characteristics
Butterfly valves have good flow control capabilities, but their flow characteristics are nonlinear, so this needs to be taken into account when adjusting the flow. If the system needs to accurately adjust the flow, it is recommended to choose a butterfly valve with flow adjustment function, or use it in combination with flow control equipment.
8. Wear resistance and lifespan
For some special media (such as mortar, sewage, etc.), it is necessary to choose a butterfly valve with strong wear resistance. High-quality valve body and sealing materials can greatly extend the service life of the butterfly valve and reduce maintenance costs.
3. Common applications of butterfly valves
Butterfly valves are widely used in the following fields:
1. Water treatment industry: used for water flow control in water plants and sewage treatment plants.
2. Petroleum and natural gas: used for fluid cut-off and regulation in pipeline systems.
3. Chemical industry: used to control the flow of chemicals, especially in pipelines with corrosive or toxic media.
4. Power industry: used for fluid regulation in boiler systems and circulating water systems.
5. HVAC system: used for air volume regulation and temperature control in HVAC systems.
4. Selection case of butterfly valves
Suppose a chemical plant needs to purchase butterfly valves to control the flow of a chemical liquid, which requires corrosion resistance, high temperature resistance, and high flow regulation accuracy. Then, the key considerations should be:
- Material: Choose stainless steel or polytetrafluoroethylene sealed butterfly valves to ensure corrosion resistance and high temperature resistance.
- Sealing method: Choose soft-sealed butterfly valves to ensure good sealing performance.
- Drive method: Consider electric or pneumatic drive for easy remote operation and automatic control.
5. Conclusion
When purchasing a butterfly valve, you must first clarify the application requirements, understand the fluid properties, temperature, pressure and other conditions, and select the appropriate material and sealing method; secondly, consider factors such as valve body size, connection method and drive method to ensure that the butterfly valve can operate stably under specific working conditions. By comprehensively considering these factors, you can choose the most suitable butterfly valve product to provide a reliable flow control solution for your industrial system.