| 摘要 |
PROBLEM TO BE SOLVED: To provide a backflow preventing flap valve with a valve box valve seat 8 having an adjustable mounting angle. SOLUTION: In the backflow preventing flap valve, an valve element 3 is rockingly lifted up to the upper part of a valve box 2 at the terminal end of an effluent pipe P and a valve seat 7 of the valve element 3 abuts on the valve seat 8 on the end face of the valve box to close the valve. The valve box valve seat 8 is fitted into the valve box 2 via an O-ring 13 with screwing 11, and fitting faces 8a, 2a of the valve box valve seat 8 and the valve box 2 are formed into spherical faces. With sliding motion on the spherical fitting faces, the valve seat 8 has a selective mounting angle in a sliding range. When the valve box valve seat 8 is replaced, there is no water leakage via the fitting faces because the fitting faces affected by rusting are uneven but the uneven fitting faces are sealed by the O-ring. The screwing 11 with an adjusting screw 12 is applied between the valve element valve seat and the valve box valve seat to just abut with each other after sliding the valve seat 8 to the valve box, thus actualizing reliable valve closing operation. COPYRIGHT: (C)2006,JPO&NCIPI
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