| 摘要 |
A butterfly valve includes a valve housing ( 1 ) having a substantially cylindrical flow passage formed therein, a disc-shaped valve element ( 4 ) arranged in the flow passage so as to be rotatable therein, a stem ( 3 ) extending from the valve element ( 4 ) to its outside and supported by the valve housing ( 1 ) so as to be rotatable, and an operating unit ( 8 ) for rotating the stem ( 3 ). The rotation of the stem ( 3 ) rotates the valve element ( 4 ) in the flow passage to open and close the flow passage. A top flange ( 2 ) for mounting the operating unit ( 8 ) is formed integrally with the valve housing ( 1 ). The top flange is formed with a plurality of cutouts ( 12 ) extending from the outer peripheral edge of the top flange toward the center thereof.
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