Generally, a complete manhole consists of the following elements:
Let us look in detail at the function of these components.
The moulded bases of manholes can be of innumerable types since, in addition to the different shapes, the number of inlets/outlets and their diameter must also be considered. The faces, in fact, accommodate the sockets that serve as connections to the inlet and outlet pipes.
Each base also has a truncated cone or socket at the top to receive the extension element.
The riser consists of a piece of pipe that rises to the surface to allow inspection inside the main pipe. A seal can be placed between the extension and the base or a weld can be made.
In some cases, a ladder can be welded onto the inside wall of the riser to facilitate the descent into the manhole for cleaning and inspection personnel.
The upper part of the manholes can be made with a conical reducer element fitted on the extension element to taper the manhole up to crawl space.
These are plates that manhole covers rest on. It is advisable to include them in cases where there is vehicular traffic.
In fact, these plates are not in direct contact with the conical reducer and therefore transfer the overloads caused by vehicular traffic to the compact backfill soil around the manhole. In this way, they do not weigh directly on the riser or the conical reducer.