| 摘要 |
<p>The watertight manhole inserts (1) have dish-shaped, square, rectangular and elliptical seals (14) or stoppers molded from a polymeric material to prevent rainwater from entering a sewer through round, square, rectangular or elliptical manholes (22) having similarly configured covers. The manhole inserts (1), located beneath the manhole covers, plug the manhole and prevent flooding of the underlying sewer. The dish-shaped, rounded or flat bowl or bottom manhole inserts (1) have a pressure-relief valve (12), optional vacuum relief valve (27), lift strap (9) and substantially perpendicular, upward-standing side wall (3) with an outwardly-extending top rim (5) engaging a shoulder (23) in the manhole supporting the manhole inserts (1). Optional multiple, upward-standing bottom (7) and side wall ribs (4) are provided to stiffen the bottom (6) and side walls (3). In a preferred embodiment, the insert rims (5) are sandwiched between two parallel elements of a ribbed rubber seal (14), the top of which seal receives the manhole cover and the bottom (20) of which includes spaced seal ribs (14) which engage the manhole shoulder (23) and act as a water barrier.</p> |
