| 摘要 |
PROBLEM TO BE SOLVED: To surely prevent the infiltration of rainwater into a manhole or the like, to which a cover is installed, and to require no closing cap and no indicating cap not marked. SOLUTION: In the valve box, which has a lower frame 1, an external cylinder 2 detachably installed on the lower frame 1 through a fixing means 9 and an internal cylinder 3 screwed inside the external cylinder 2 in a freely lifting- lowering manner and in which a flange 8 is formed to the lower section of the external cylinder 2 and the internal cylinder 3 is freely opened and closed by the cover 6, ribs 1A for preventing an accompanying turn are formed to the lower frame 1. The fixing means 9 is composed of a receiving section 1B, which is formed to the top face of the lower frame 1 and to which a part 8A of the flange 8 for the external cylinder 2 is inserted, and a clamping means 10 fixing a flange 8B on the side opposed to a part 8A of the flange inserted into the receiving section 1B onto the lower frame 1. COPYRIGHT: (C)2003,JPO
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