How does a butterfly valve control water flow?

A butterfly valve controls water flow by rotating a circular plate, known as a disc, typically by 90 degrees. This rotation either allows or restricts the flow of water through the pipe. When the valve is in the open position, the disc is parallel to the flow of water, minimizing resistance and allowing for maximum flow. Conversely, when the valve is turned to the closed position, the disc turns perpendicular to the flow, effectively blocking the water passage. This design is advantageous for its compact size and ability to open or close rapidly with less force, making it suitable for various applications in fluid management systems.