Molded manhole unit

Abstract

A corrosion resistant manhole unit having a rotationally molded plastic manifold forming a hollow chamber for providing access to sewer pipes to be connected to the manifold. A manifold inlet connector molded into the manifold for connecting the manifold to an upstream conduit and allowing an inflow of fluid to the hollow chamber. A manifold outlet connector molded into the manifold for connecting the manifold to a downstream conduit so that fluid flows out of the hollow chamber. A manifold riser molded atop the manifold having an open top forming an aperture for accessing the hollow chamber. The manifold riser extending upward from the manifold towards ground level for allowing equipment and personnel to access the hollow chamber through the aperture. A watertight removable riser cap is included for sealing the top of the riser to close and prevent fluid and debris from entering or leaving the manifold.

What is claimed is:  
     
         1 . A single-piece corrosion resistant manhole unit for placement underground to connect with a conduit system in a watertight manner and provide access to the conduits for inspection, maintenance, and repair, said manhole comprising: 
 a rotationally molded polyethylene manifold forming a hollow chamber for providing access to conduits to be connected to said manifold;    a plurality of lateral manifold extensions molded into said manifold for connecting to said conduits to facilitate the flow of fluids through the hollow chamber;    at least one manifold inlet connector included in said manifold extensions for connecting the manifold to an upstream conduit spigot and allowing an inflow of fluid to said hollow chamber;    a manifold outlet connector included in said manifold extensions for connecting the manifold to a downstream conduit bell and allowing fluid to flow out of said hollow chamber; and,    a manifold riser molded atop said manifold and extending upward from said manifold towards ground level for allowing equipment and personnel to access said hollow chamber;    whereby a cost effective, lightweight, and corrosion resistant manhole is provided that can be quickly and easily installed with watertight seals to reduce the problems of overflow and surcharge associated with leaking conduits.    
     
     
         2 . The manhole unit of  claim 1  including a plurality of reinforcing ribs molded into said manifold; said reinforcing ribs protruding from the manifold to increase the structural integrity of the manifold to withstand external pressures applied to the manifold when buried underground.  
     
     
         3 . The manhole unit of  claim 1  including a fluid channel molded into said manifold between said manifold inlet and outlet connectors for channeling fluid through said hollow chamber.  
     
     
         4 . The manhole unit of  claim 3  wherein said fluid channel is declined to form a downward gradient through said hollow chamber from said inlet connector to said outlet connector so that fluid is caused to flow through the hollow chamber in the fluid channel and continues through the conduit system.  
     
     
         5 . The manhole unit of  claim 1  wherein said manifold inlet connector includes an annular seal for sealing between said manifold inlet connector and said upstream conduit spigot; said annular seal conforming to surface variations in the shape of said conduit spigot to form a watertight connection;  
     
     
         6 . The manhole unit of  claim 5  wherein said annular seal is carried on an interior side of said manifold inlet connector so that the annular seal is protected from exposure to environmental corrosive agents surrounding the conduits.  
     
     
         7 . The manhole unit of  claim 6  including a seating groove molded into said interior side of said manifold inlet connector for receiving said annular seal; said seating groove restricting the seal from moving when said downstream conduit spigot is slid into said manifold inlet connector and contacts the seal to form the watertight connection.  
     
     
         8 . The manhole unit of  claim 1  wherein said manifold outlet connector includes a beveled spigot edge at a distal end of said outlet connector; said beveled spigot edge reducing the thickness of the distal end of the outlet connector for engaging a seal member carried by said downstream conduit bell and allowing the seal member to easily slide over said beveled spigot edge to move into position around the outlet connector and form a watertight connection.  
     
     
         9 . The manhole unit of  claim 1  including a riser extension for connecting with said manifold riser; said riser extension receiving said manifold riser to extending the height of said manifold riser to ground level when buried underground, so that access to said hollow chamber can be maintained at ground level when the manifold riser is of insufficient height to reach ground level.  
     
     
         10 . The manhole unit of  claim 9  including a sealing ring carried by said riser extension for sealing between said manifold riser and said riser extension; said sealing ring conforming to surface variation in the shape of said riser to provide a watertight connection between said manifold riser and said riser extension.  
     
     
         11 . The manhole unit of  claim 10  wherein said sealing ring is carried on an interior side of said riser extension so that the sealing ring is protected from exposure to environmental corrosive agents surrounding the riser extension.  
     
     
         12 . The manhole unit of  claim 10  wherein said sealing ring includes a hollow deformable o-ring for compressing against said manifold riser and forming to the surface shape of said manifold riser to provide the watertight connection.  
     
     
         13 . The manhole unit of  claim 10  wherein said manifold riser includes a beveled riser edge at a distal end of said manifold riser; said beveled riser edge reducing the thickness of the distal end of the riser for engaging said sealing ring and allowing the sealing ring to easily slide over said beveled riser edge to move into position around the riser and form a watertight connection.  
     
     
         14 . The manhole unit of  claim 1  including a removable riser cap for sealing the manifold riser closed to prevent fluid and debris from entering or leaving the manifold.  
     
     
         15 . The manhole unit of  claim 14  including an adaptive seal carried by said removable riser cap for sealing between said cap and said manifold riser; said adaptive seal conforming to surface variation in the shape of said riser to provide a watertight connection between said manifold riser and said cap.  
     
     
         16 . The manhole unit of  claim 15  wherein said adaptive seal includes a hollow deformable o-ring for compressing against said manifold riser and conforming to the surface shape of the manifold riser to provide the watertight connection.  
     
     
         17 . The manhole unit of  claim 14  including a pressure release valve disposed within said removable riser cap for venting built-up gases from said hollow chamber.  
     
     
         18 . The manhole unit of  claim 14  including a vacuum ventilation valve disposed within said removable riser cap for allowing excess gases formed in said hollow chamber to be vacuumed out before attempting to remove said removable riser cap.  
     
     
         19 . A corrosion resistant manhole unit for placement underground to connect with conduits of a sewage system, and the like, in a watertight manner and provide access to the conduits for inspection, maintenance, and repair, said manhole comprising: 
 a molded plastic manifold having a hollow chamber for providing access to sewage system conduits to be connected to said manifold;    a bell inlet connector extending laterally from said manifold for connecting the manifold to an upstream sewage conduit to facilitate the flow of sewage into said manifold;    an annular seal carried by said bell inlet connector for forming a watertight seal between said bell and said upstream sewage conduit;    a spigot outlet connector extending laterally from said manifold for connecting the manifold to a downstream sewage conduit to allow sewage to flow out of the manifold; and,    a fluid channel molded into said manifold between said bell inlet and spigot outlet connectors for channeling sewage through said hollow chamber;    whereby a cost effective, lightweight, and corrosion resistant manhole is provided that can be quickly and easily installed with watertight seals to reduce the problems of overflow and surcharge associated with leaking conduits.    
     
     
         20 . The manhole unit of  claim 19  wherein said fluid channel is declined to form a downward gradient through said hollow chamber from said bell inlet connector to said spigot outlet connector so that fluid is caused to flow through the hollow chamber in the fluid channel and continues through the sewage system.  
     
     
         21 . The manhole unit of  claim 19  wherein said annular seal is carried on an interior side of said bell so that the annular seal is protected from exposure to environmental corrosive agents surrounding the sewage system conduits.  
     
     
         22 . The manhole unit of  claim 21  including a seating groove molded into said interior side of said bell inlet connector for receiving said annular seal; said seating groove restricting the seal from moving when said upstream sewage conduit is slid into said bell and contacts the seal to for a watertight connection.  
     
     
         23 . The manhole unit of  claim 19  wherein said spigot outlet connector includes a beveled spigot edge at a distal end of said spigot; said beveled spigot edge reducing the thickness of the distal end of the outlet connector for engaging a seal member carried by said downstream conduit and allowing the seal member to easily slide over said beveled spigot edge to move into position around the spigot and form a watertight connection.  
     
     
         24 . A corrosion resistant manhole unit for placement underground to connect with a conduit system in a watertight manner and provide access to the conduits for inspection, maintenance, and repair, said manhole comprising: 
 a molded plastic manifold forming a hollow chamber for providing access to conduits to be connected to said manifold;    a manifold inlet connector molded into said manifold for connecting the manifold to an upstream conduit and allowing an inflow of fluid to said hollow chamber;    a manifold outlet connector molded into said manifold for connecting the manifold to a downstream conduit so that fluid flows out of said hollow chamber;    a manifold riser carried atop said manifold having an open top forming an aperture for accessing said hollow chamber, said manifold riser extending upward from said manifold towards ground level for allowing equipment and personnel to access said hollow chamber through said aperture; and,    a removable riser cap for sealing the top of said riser to close and prevent fluid and debris from entering or leaving the manifold;    whereby a cost effective, lightweight, and corrosion resistant manhole is provided that can be quickly and easily installed with watertight seals to reduce the problems of overflow and surcharge associated with leaking conduits.    
     
     
         25 . The manhole unit of  claim 24  including a riser extension for connecting with said manifold riser; said riser extension receiving said manifold riser to extending the height of said manifold riser to ground level when buried underground, so that access to said hollow chamber can be maintained at ground level when the manifold riser is of insufficient height to reach ground level.  
     
     
         26 . The manhole unit of  claim 25  including a sealing ring carried by said riser extension for sealing between said manifold riser and said riser extension; said sealing ring conforming to surface variation in the shape of said riser to provide a watertight connection between said manifold riser and said riser extension.  
     
     
         27 . The manhole unit of  claim 26  wherein said sealing ring is carried on an interior side of said riser extension so that the sealing ring is protected from exposure to environmental corrosive agents surrounding the riser extension.  
     
     
         28 . The manhole unit of  claim 26  wherein said sealing ring includes a hollow deformable o-ring for compressing against said manifold riser and forming to the surface shape of said manifold riser to provide the watertight connection.  
     
     
         29 . The manhole unit of  claim 26  wherein said manifold riser includes a beveled riser edge at a distal end of said manifold riser; said beveled riser edge reducing the thickness of the distal end of the riser for engaging said sealing ring and allowing the sealing ring to easily slide over said beveled riser edge to move into position around the riser and form a watertight connection.  
     
     
         30 . The manhole unit of  claim 24  wherein said manifold riser is molded with said manifold as a single unit.  
     
     
         31 . The manhole unit of  claim 24  including an adaptive seal carried by said removable riser cap for sealing between said cap and said manifold riser; said adaptive seal conforming to surface variation in the shape of said riser to provide a watertight connection between said manifold riser and said cap.  
     
     
         32 . The manhole unit of  claim 31  wherein said adaptive seal includes a hollow deformable o-ring for compressing against said manifold riser and conforming to the surface shape of the manifold riser to provide the watertight connection.