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:
- 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.
- Flow Regulation: By adjusting the disc angle (0°–90°), the flow cross-sectional area changes to control flow rate.
- Sealing Mechanism:
- Centerline/Single Eccentric Design: Relies on seat compression against the disc, suitable for low-pressure applications.
- Triple Eccentric Design: Achieves metal-to-metal hard sealing via three-dimensional offset, enabling bidirectional pressure resistance and high-temperature tolerance.
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Maintenance Key Points for Butterfly Valves
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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.
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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.
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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.
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