| 摘要 |
PCT No. PCT/JP90/01651 Sec. 371 Date Aug. 19, 1991 Sec. 102(e) Date Aug. 19, 1991 PCT Filed Dec. 18, 1990 PCT Pub. No. WO91/09243 PCT Pub. Date Jun. 27, 1991.In a ball valve wherein the rotation of a ball (1) provided in a valve chest (8) opens and closes a valve, an orifice (4) is provided in a passage (3) of the ball, and communicating passages (5) connecting the upstream side of the orifice (4) with the valve chest (8) and communicating passages (6) connecting the downstream side of the orifice with the valve chest (8) are provided. The passage (3) provided in the ball (1) has a large aperture at one end (30) and a small aperture at the other end (31), the respective communicating passages (5) (6) are formed so as to communicate the passage (3) with the valve chest (8) when the valve is opened, and the aperture of the passage (32) whereat a seat carrier (11) of the small aperture side of the ball faces the ball is made substantially the same as the aperture of the small aperture side end (31) of the passage of the ball (1).
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