Please find attachment of below a link to a short video introducing Manhole Systems.
Please find below a short brief on precast manhole systems.
A typical drawing of circular manhole system is also attached.A typical Manhole System includes the following components
Depending on the specific requirements for the Manhole System other components may be included. The following types of components are often used:
Base Section:The Base section has several functions. The Base Section must
Riser Sections:The function of the Riser Sections is to provide a safe access connection from ground level to the pipeline. Riser Sections are standardized components normally supplied in different lengths. Riser Sections can be specified with provisions for the installation of steps. For the handling of the Riser Sections the can be made with lifting holes or cast in lifting provisions that makes it easy for the contractor handle and install the Riser Section.
Cone Sections:It is a very common to install a Cone Section on top of the Riser Section. The function of the Cone Section is to reduce the diameter of the top Cover and still provide an opening large enough for a person to enter into the Manhole System. Also the Cone Section has the function of distributing an eventual traffic load to the Riser Sections and further down to the Base Section. By using Eccentric Cones a straight vertical access is provided for the persons entering the Manhole System. Cone Section like the Riser section can be supplied with provisions for steps and also with lifting provisions.
Adjusting Rings:The function of the Adjusting Rings is to be bring the top level of the Manhole Systems ( the cover ) to match the ground level ( or any other specified level ). Adjusting Rings can be made as flat rings or with a tongue/groove configuration to prevent the rings from shearing off the Cone Section. Adjusting Rings are normally supplied indifferent heights. Common heights are: 50 mm, 100 mm, 150 mm and 200 mm.
Covers:The function of the Cover is to close the access to the Manhole System.
Transition Slabs:The function of a Transition Slab is to provide a connection between a Base Section and the Manhole System providing access to the pipeline. The Transition Slab is required because the diameter of the Base section is larger than the diameter of the Manhole System installed for access.
Top Slab:When a pipeline is not installed deep enough to allow installation of a Cone Section a Top Slab with an Dia.600 mm access opening can be installed. The Top Slab provides access to the Manhole System in the same way as a Cone Section.