| 摘要 |
PROBLEM TO BE SOLVED: To provide a drainage perforated plate of which the float valve favorably goes down due to its own weight without an interference with the surface tension of the drainage even if surface tension occurs which cuts off even if the float valve displaces and prevents scale or the like of the valve from clogging to secure favorable cut-off performance and prevents the deterioration of the valve due to drainage. SOLUTION: The perforated plate is constituted of a top face water-tightly attached to an outlet, an opening opened at the top face, and a float valve closing the opening. A protruded groove or a recessed groove is formed at the peripheral edge of the lower face of the opening. COPYRIGHT: (C)2005,JPO&NCIPI
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