| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball valve capable of certainly relieving a fluid pressure abnormally raised in a cavity, retaining the pressure in the cavity to a normal value and being not restricted in a pressure loading direction with respect to a ball valve element. SOLUTION: In the ball valve, the ball valve element 6 having a penetration hole 5 is stored in the cavity 4 provided with a pair of seal rings 3, 3 formed on a flow passage 2 in the valve body 1 and opposed in an axial direction. A relief hole 7 for connecting the flow passage 2 with the penetration hole 5 is provided on the ball valve element 6 in the valve-closed state of the flow passage 2, and a relief valve 10 is provided on the relief hole 7. When the fluid pressure P in the cavity 4 is higher than a set pressure P<SB>0</SB>of the relief valve, the relief valve 10 is opened to relieve the fluid pressure P in the cavity 4 by releasing the fluid to the flow passage 2. COPYRIGHT: (C)2008,JPO&INPIT
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