| 摘要 |
PURPOSE: To provide a butterfly valve, in which a valve element peripheral portion almost simultaneously abuts on protrusions of a seat ring. CONSTITUTION: By gradually varying inclination of a pressure contact surface 28 of the protrusion 26, the pressure contact surface 28 in the vicinity of a valve shaft 3 is sharply inclined, and the surface 28 far from the valve shaft 3 is gently inclined. The abutting portion 31 of the pressure contact surface 28 abutting on the peripheral portion of the valve element 2 is expanded to an opening direction side more in a portion far from the valve shaft 3 than in the vicinity of the valve shaft 3. The peripheral portion of the valve element 2 almost simultaneously abuts on an abutting portions of protrusions 26 of the peripheral portion of the valve element 2.
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