Patent ID: 9004810
Filing Date: 2015-04-14
Classification: E02D

Abstract:
1. A manhole cover adapted to move from a seated position to an unseated position with respect to a frame to relieve pressure, the frame having a manhole cover receiving surface and a peripheral wall defining an access opening, said manhole cover comprising: a cover portion having an upper face, an outer peripheral edge, and an underside opposing said upper face; a first leg and a control leg extending from said cover portion, wherein said first leg and said control leg extend away from said underside toward said access opening; whereby in response to pressure on said underside reaching a threshold, at least a portion of said cover portion displaces from a seated position to an unseated position such that fluid flows through the access opening; wherein in said unseated position, said first leg and said control leg cooperate with the frame to enable said at least a portion of said cover portion to have a range of movement with respect to the manhole receiving flange, wherein said legs contact the frame at a limit of said range to prevent said cover portion from moving beyond said limit of said range; and wherein in said unseated position, said range of movement varies about said outer peripheral edge of said cover, such that a first region of said peripheral edge of said cover is displaced a greater distance from said seated position than a second region of said peripheral edge.