Working Principle and Structure of Butterfly Valves
A butterfly valve is a type of valve that opens and closes by rotating the valve stem to turn the disc. Its working principle relies on the disc-shaped disc inside the cylindrical channel of the valve body, which rotates around an axis. Flow control is primarily achieved through a 90° rotation. When the disc rotates to 90°, the butterfly valve is fully open, and the flow rate of the medium can be precisely adjusted by varying the disc angle. These valves are typically installed along the pipeline diameter.
It is important to note that butterfly valves inherently lack a locking function. To achieve effective flow regulation, a worm gear reducer is often installed. Equipped with a worm gear reducer, the butterfly valve gains self-locking capability and significantly improves its operational performance, allowing for more accurate control of the medium flow.
Structure of Butterfly Valves
Valve Body
The main pressure-bearing component of the valve, providing a flow channel for the medium and connecting to the pipeline. Typically manufactured via casting or forging, materials include cast iron, cast steel, stainless steel, and alloys.
Disc (Butterfly Plate)
The core opening/closing component. Its design varies, including center-symmetric plate, inclined plate, and fishtail shapes, each optimized to reduce flow resistance, improve sealing, or suit specific media.
Valve Stem
A transmission part connecting the actuator (e.g., handwheel, gearbox, or electric drive) to the disc, transferring operating torque. The stem must have sufficient strength and stiffness to prevent torsion failure.
Seat
A sealing element installed on the inner valve body or disc edge. When closed, the disc edge tightly contacts the seat to form a sealing pair, preventing leakage. Seat material is critical for sealing performance and lifespan.
Sealing Structure & Bearing
Dynamic seals (e.g., packing or O-rings) between the stem and valve body, along with bearings supporting stem rotation, ensure smooth operation and sealing integrity.
Technical drawn
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