Eccentric/Offset Butterfly Valve

Eccentric butterfly valves, also known as single eccentric butterfly valves, are a type of quarter-turn valve commonly used for controlling the flow of fluids in various industrial applications. The term “eccentric” refers to the offset or eccentricity of the valve shaft from the centerline of the valve body. Here are key features and characteristics of eccentric butterfly valves:

  1. Eccentric Design:
    • The eccentricity in these valves refers to the offset of the shaft from the centerline of the valve body. This design allows the disc to move away from the valve seat with minimal friction during operation.
  2. Butterfly Disc:
    • The valve disc or butterfly is mounted on the shaft and positioned off-center within the valve body. When the valve is open, the disc rotates perpendicular to the flow direction, allowing for unrestricted flow.
  3. Seating Options:
    • Eccentric butterfly valves can have either soft or metal seats. Soft seats are typically made of materials like rubber, elastomers, or PTFE for applications where tight shut-off is required, while metal seats are used for higher-temperature and more robust applications.
  4. Low Torque Requirement:
    • The eccentric design results in a lower torque requirement for valve operation. This contributes to ease of actuation and can reduce wear on the valve components.
  5. Bi-Directional Sealing:
    • Eccentric butterfly valves are designed for bi-directional sealing, meaning they can provide a tight seal regardless of the flow direction. This feature adds versatility to their applications.
  6. Applications:
    • These valves are commonly used in various industries, including water treatment, HVAC systems, chemical processing, power generation, and general fluid-handling applications.
  7. End Connections:
    • Eccentric butterfly valves can have different end connections, including wafer, lug, or flanged designs. The choice of end connection depends on the specific requirements of the piping system.
  8. Manual and Automated Operation:
    • Eccentric butterfly valves can be operated manually using a lever or handwheel. They can also be automated using electric or pneumatic actuators for remote control and precise flow regulation.
  9. Versatility:
    • These valves are versatile and find application in various fluid-handling systems, including those involving water, air, gas, and a range of process fluids.
  10. Cost-Effective:
    • Eccentric butterfly valves are often considered cost-effective solutions for applications where tight shut-off is not critical, and moderate pressure drops are acceptable.
  11. Ease of Installation and Maintenance:
    • Eccentric butterfly valves are generally easy to install and maintain due to their simple design and fewer components compared to other types of valves.

While eccentric butterfly valves are suitable for many applications, their use may be limited in scenarios where absolute tight shut-off is required or in applications with high-pressure differentials. Careful consideration of the specific requirements of the system, including pressure, temperature, and fluid characteristics, is essential for proper valve selection and performance. Regular maintenance and adherence to manufacturer recommendations contribute to the efficient and reliable operation of eccentric butterfly valves.

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