| 摘要 |
A water pressure adjustable double manhole cover is provided to prevent displacement of manhole cover and damage of manhole because the sewage is flowed backward and in order to be maintained less than the constant pressure the water pressure of the inside man-hole is controlled. A water pressure adjustable double manhole cover(100) comprises a main body member(110) forming an opening and closing hole penetrated toward the center with a constant size, and an opening and closing cover(120) hanging on the main body member by the lower part and limit the translation distance. |
