Working Principle of Butterfly Valves

Working Principle of Butterfly Valves

Butterfly valves control fluid flow by rotating a disc (butterfly plate) around its stem axis. Key components include the valve body, disc, stem, and sealing ring. The operating principle is as follows:

1. ‌Opening/Closing Action‌: The disc rotates 90° around the stem axis—when fully open, it aligns parallel to the flow; when closed, it perpendicularly blocks the passage.
2. ‌Flow Regulation‌: By adjusting the disc angle (0°–90°), the flow cross-sectional area changes to control flow rate.
3. ‌Sealing Mechanism‌:
4. Centerline/Single Eccentric Design‌: Relies on seat compression against the disc, suitable for low-pressure applications.
5. ‌Triple Eccentric Design‌: Achieves metal-to-metal hard sealing via three-dimensional offset, enabling bidirectional pressure resistance and high-temperature tolerance.

6. Maintenance Key Points for Butterfly Valves‌

   1. ‌Sealing Inspection‌

      • Check for aging or wear of sealing rings, especially in corrosive media environments, and replace them periodically.
      • Perform pressure tests to verify seat leakage and ensure bidirectional sealing performance.

   2. ‌Mechanical Component Maintenance‌

      • Lubricate the stem and worm gear reducer to prevent jamming.
      • Inspect the disc for deformation or corrosion; multi-layer discs require disassembly for layer-by-layer inspection.

   3. ‌Special Maintenance for Signal Butterfly Valves‌

      • Clean feedback contacts to ensure accurate switch signal transmission.
      • Ensure manual operation mechanisms move smoothly without resistance to avoid stem bending due to forced operation.