| 摘要 |
PROBLEM TO BE SOLVED: To provide a manhole cover capable of preventing odor from leaking therefrom while making releasable the inner pressure of the pipe. SOLUTION: In this manhole cover 1A, the sediment or the like flowing on a ground surface GL in case of rain does not adhere to a packing 10 since a high stage part 6 is set on a cover body 5A and the packing 10 is disposed at the upper end of the high stage part 6. Since the sediment is not caught between a valve element 2A and the packing 10 in normal times, the manhole cover can reliably prevent odor from leaking. COPYRIGHT: (C)2011,JPO&INPIT |
