| 摘要 |
PROBLEM TO BE SOLVED: To ensure a sufficient amount of ventilation while miniaturizing a device to simplify mounting construction, to facilitate inspection/repair or the like and to immediately cope with an installation space, not to mention reliable elimination of trouble in a drain pipe. SOLUTION: This ventilator for drainage is provided with a normally closed check valve 14 in a position adjacent to an intermediate part of the drain pipe 3 piped in a vertical or horizontal direction. The check valve is springingly energized to the primary side by energizing force to the extent of releasing a valve element against negative pressure in the drain pipe, and the check valve and the drain pipe are connected through a communicating part of approximately rectangular cross section. COPYRIGHT: (C)2008,JPO&INPIT
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