| 摘要 |
PROBLEM TO BE SOLVED: To promote drainage by easily opening a valve element with a small flow by supporting a flap valve to freely swing round the shaft center of a horizontal support shaft, and forming a downward inclined passage on the lower side part of an opening edge of a drain port of a valve easing toward the flat valve. SOLUTION: This flap valve 13 is so constructed that a valve easing 14 is connected to a conduit pipe 11, and a flap valve element 16 for opening and closing a drain port 15 of the valve casing 14 is supported by a holder part 18 provided on the valve casing 14 to freely swing round the shaft center of a horizontal support shaft 17. The axis (b) of an internal passage 14A of the valve casing 14 is inclined at a designated angleθto the axis (a) of the conduit pipe 11 to become lower as it goes toward the drain port 15. That is, at the inclined lower end part of the internal passage 14A of the valve casing 14, a lower part below the axis (b) of the internal passage 14A is formed like a square to form a downward inclined passage 19 toward the flap valve element 16. Thus, draining can be smoothly performed even in the case of a small quantity of drainage.
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