How does a butterfly valve work

The principle of operation of a butterfly valve is based on the flow of fluid being blocked by a flat disc that rotates around the stem axis. The disc is rigidly attached to the stem, whose axis is perpendicular to the flow direction.

In the closed position, the plane of the disc is perpendicular to the pipeline axis and blocks the entire passage of the valve. Turning the handle 90 degrees rotates the disc to a plane parallel to the flow direction, opening the passage.

One of the disadvantages of butterfly valves is that in the open position, the disc is in the center of the flow, making full passage impossible for this type of valve.

The sealing of the closure is achieved by the tight fit of the disc edge to a polymer sleeve in the flow part of the body. In addition to sealing, the polymer sleeve protects the valve body from contact with the working environment and also serves as a seal between the flanges and the butterfly valve body during flange assembly.

The axis of rotation of the disc may intersect with the axis of the pipeline or be offset from it.

Handles are used for manual control of butterfly valves up to DN150 in diameter, while larger sizes use gear actuators. For automatic control, the disc valve can be equipped with an electric actuator.

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