| 摘要 |
A liquid-tight manhole closure structure including a base frame having a manhole opening therein, a manhole cover for placement in the manhole opening, and a retainer ring for detachably securing the cover on the frame. The retainer ring and frame having peripheral coacting, detachably interlocking, cam surfaces for removably securing the ring to the frame. A resilient sealant is disposed between the cover and the frame to prevent liquid seepage through the manhole opening. The sealant may be vulcanized or otherwise secured directly to the periphery of the cover and/or to the frame.
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