Butterfly Valve
A butterfly valve is a quarter-turn valve used to regulate or isolate the flow of fluid in a pipeline. Its simple design, low cost, and fast operation make it a popular alternative to other valves, especially in large-diameter applications. A 90-degree rotation of the internal disc controls the flow of media, which can be liquids, gases, or slurries.
Key Features
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Quarter-Turn Operation
A 90-degree rotation of the stem, controlled by a lever or handwheel, quickly opens or closes the valve.
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Compact and Lightweight
Their small footprint and low weight, compared to other valve types like gate or globe valves, result in lower installation costs.
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Simple Design
With only a disc, stem, and seat, butterfly valves have few moving parts, contributing to their simplicity and lower maintenance needs.
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Low Pressure Drop
In the fully open position, the disc aligns with the flow, causing minimal resistance and a minimal pressure loss through the valve.
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Cost-Effective
Due to their simple design and use of less material, they are often an economical choice, particularly for larger sizes.
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Versatility
They can be used for both controlling flow (modulating) and for on-off applications, and are suitable for a wide range of fluids.
Disadvantages and Limitations
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Disc in Flow Path
The central disc remains in the flow stream, which can cause some flow resistance even when the valve is open.
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Limited Seal
Standard butterfly valves may not provide a truly tight seal, which is why they are best for low-pressure situations or where some leakage is acceptable.
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Unsuitability for Some Applications
The presence of the disc makes them unsuitable for pipelines that need to be "pigged" (cleaned with a device that travels through the pipe) and can cause issues with media containing solids.
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Potential for Cavitation
In certain throttling scenarios, the flow restriction can lead to cavitation.
