Butterfly Valves: Selection Principles and Key Applications

 
Butterfly valves are simple yet efficient control valves widely used for switching control in low-pressure pipeline media. These valves feature a circular disc as the closing element (valve disc or butterfly plate) that rotates around a valve shaft to achieve opening and closing. In pipeline systems, butterfly valves primarily serve to cut off and throttle flow, making them suitable for transporting various corrosive and non-corrosive fluid media.
 

Principles for Selecting Butterfly Valves

 
Selecting the appropriate butterfly valve for a given application involves several key considerations to ensure optimal performance and longevity. Below are the principles to guide the selection process.
 

• Pressure Loss: Due to the relatively high pressure loss of butterfly valves compared to gate valves and ball valves, they are suitable for pipeline systems where pressure loss requirements are not stringent.
• Flow Regulation: Butterfly valves excel in flow regulation, making them ideal for pipelines requiring flow control.
• Temperature and Pressure Limits: Given the structural and sealing material limitations of butterfly valves, they are not suitable for high-temperature and high-pressure pipeline systems. Generally, butterfly valves are used where the operating temperature is below 300°C and the nominal pressure is below PN40.
• Structure Length and Diameter: Butterfly valves have a short structural length and can be made in large diameters, making them suitable for situations where a short structural length or large diameter valve (e.g., DN1000 and above) is required.
• Quick Operation: Butterfly valves can be fully opened or closed with a 90° rotation, making them suitable for applications requiring fast operation.

 

Suitable Applications for Butterfly Valves

Butterfly valves are versatile tools for fluid control, known for their efficiency and adaptability across industries. This part showcases their suitability for diverse applications, emphasizing their effectiveness in meeting specialized requirements with precision and reliability.
 

1. Throttling and Control: Butterfly valves are recommended for use in slurry media where a short structural length, quick opening and closing (1/4 turn), and low-pressure cut-off (small pressure differential) are required.
2. Special Conditions: Butterfly valves are suitable for dual-position regulation, constricted passageways, low noise, absence of cavitation and vaporization, minimal leakage to the atmosphere, and abrasive media.
3. Strict Sealing Requirements: For special conditions requiring throttling regulation, strict sealing, severe wear, or low-temperature (cryogenic) conditions, specially designed metal-sealed triple-eccentric or double-eccentric butterfly valves with regulating devices are necessary.
4. Centerline Butterfly Valves: These valves are suitable for fully sealed applications, with zero leakage in gas tests, high longevity requirements, and operating temperatures between -10 to 150°C, in pipelines carrying freshwater, wastewater, seawater, saltwater, steam, natural gas, food, pharmaceuticals, oils, and various acids and bases.
5. Soft-Sealed Eccentric Butterfly Valves: These are used for bidirectional opening, closing, and regulation in ventilation and dust removal pipelines, commonly found in metallurgical, light industry, power, and petrochemical systems for gas and water pipelines.
6. Metal-to-Metal Sealed Double-Eccentric Butterfly Valves: These are suitable for city heating, steam, water supply, gas, oil, and acid-base pipelines, serving as regulating and shut-off devices.
7. Metal-to-Metal Sealed Triple-Eccentric Butterfly Valves: In addition to being used as program control valves in large-scale Pressure Swing Adsorption (PSA) gas separation units, they are widely used in petroleum, petrochemical, chemical, metallurgical, and power industries as excellent alternatives to gate valves and globe valves.

 
In summary, butterfly valves are crucial for efficient fluid control in various industries. Their design allows quick operation and effective flow regulation, ideal for low to medium-pressure systems. Proper selection based on application requirements ensures optimal performance and longevity. Their versatility and adaptability make them a reliable choice for critical applications, enhancing the efficiency of fluid control systems across multiple sectors.