Working principle of butterfly valve

Working principle of butterfly valve

The working principle of butterfly valves is based on the principle of "valve disc rotation changing the flow cross-section", which achieves the on/off or flow regulation of the medium through simple mechanical motion. The specific process is as follows:

Closed status

The valve disc (butterfly plate) rotates to be perpendicular to the axis of the valve body channel (90 °), at which point the valve disc completely covers the valve body channel, tightly adheres to the seal, blocks the flow of the medium, and achieves the "closing" function.

Open

When the driving device drives the valve stem to rotate, the valve disc rotates synchronously with the valve stem:

When rotating 0 °: the valve disc is parallel to the axis of the valve body channel, with the maximum flow cross-section, and the medium can completely pass through (fully open state);

Rotation between 0 ° -90 °: The valve disc partially obstructs the channel, and the flow cross-section decreases with increasing rotation angle, allowing for adjustable medium flow rate;

When rotated 90 °: the valve disc completely blocks the channel, and the medium cannot pass through (fully closed state).

seal principle

When closed, the valve disc compresses the sealing element (such as a rubber valve seat), filling the gap with the elastic deformation of the sealing element to achieve sealing;

Some high-pressure butterfly valves will use "metal hard seals", which achieve sealing through precision machining (such as grinding) of the valve disc and valve body, relying on metal surface contact, suitable for high temperature and high pressure scenarios.