Manhole Chambers & Risers
Our budget manhole bases, chambers and risers are manufactured in the UK and are kitemarked, meaning they’ve been tested and approved for use. The come 320mm and 450mm in size and have a 110m or 160mm outlet size. They are compatible with Polypipe and other major brands made to the same size.
A manhole chamber is a necessity in any home or commercial property. Whether your project is big or small, any building contractor who handles the installation of the drainage system will need to use the access point, so choose one that will serve you well.
If you're planning to install underground drainage, perhaps, as part of a renovation project, there is a chance you will have to install multiple inspection chambers with fittings for the sewage. What are these chambers, and what purpose do they serve? Read on and find out.
Below, we explain what an inspection chamber (IC) is and what a disconnecting chamber does precisely. We also look at the purpose of the inspection chamber, describing various similar units and depths, as well.
What Is The Function of The Inspection Chamber?
The primary role of an inspection chamber is to provide an easy, large enough access point into a storm drain or sewer systems for inspection, manual cleaning procedures, and sampling.
If that’s not the answer your expected, these entries also allow drainage professionals to carry out maintenance work out from the ground level.
Common IC uses include:
Line clean-out access
Effluent sampling stations
Interim access points for long pipes (22 meters or longer)
You will need to install an inspection chamber whenever your pipework changes direction (exceeding 30 degrees) before emptying to the sewer. It's necessary to install it where there is a change of gradient (start and endpoint) in sloping land, too.
Building regulations typically govern the use of the inspection chamber and its fittings.
The mainline adapt-a-valve inspection chamber can also serve as a backwater valve to protect the home or commercial property against municipal back surge or isolate sewer laterals. Water in the manhole means the blockage is on the municipality side.
It provides access to sewers and drains for purposes like effluent sampling—the mainline adapt-a-valve inspection chamber is used to run a pressure test on the lateral or isolate it. The manhole chamber also acts as a vital storage point for water. It will collect and hold water in the drainage system instead of flooding it, which could be your answer to perennial flooding.
Before selecting an inspection chamber, check the size of the fittings, especially the drainage pipe and the type of pipe. It's also important to consider the inspection chamber cover level or depth and its configuration.
Another crucial factor is depth, which determines what type of chamber to install or manhole to use.
What Is The IC?
An inspection chamber (IC), also known as a manhole, is a sectional entry point to underground drainage and sewer. It creates an access point that enables technicians to clean, clear, and inspect drains when necessary.
It is also a way to stop people from entering the manhole without authorisation. Risk assessments and method statements are required to access the space, for example.
Chambers can be rectangular (with a concrete cover) or circular. A typical chamber consists of the base (or bottom), sealed risers, and a manhole cover made from plastic, brick, steel, or concrete.
Inspection chambers are made from precast concrete and thick polyethylene plastic (HDPE). The products are available in different styles, such as prefabricated HDE chambers, wide wall concrete rings, and standard concrete manhole rings.
What's the best material? The answer depends on the size of the IC, its purpose, and the diameter and depth of the chamber. It also depends on whether a person has to access it.
Some manhole covers are a few meters deep, enabling a person to see the inside of the pipe when the cover is removed. Often, it leads to deeper drains and sewer systems several meters underground, requiring ladders on one side for safe access.
Pipes outside the manhole chamber have to connect to a rocker joint to accommodate a slight ground movement that may affect the connection. It will ensure that any change does not fracture or split the pipes. Manholes previously had steps built into the wall for a descent into the drainage.
Manhole covers are available in various shapes and sizes, depending on the pipe used and the position. Bigger, stronger, and thicker covers are commonly in locations with heavy vehicles or traffic over the top of the chamber. Larger access points also require steel grills to stop unauthorised access and prevent debris or items from being thrown inside.
What lies at the bottom? The answer depends on factors, such as depth of drainage pipe, purpose, and size, and whether it leads to a piece of equipment, like a sump pump.
What Is A Disconnecting Chamber?
Every new home that has a drainage system ought to have a disconnecting chamber. The manhole sits at the boundary of a home, where the foul pipe connects to the gravity pipework (just before it flows to the main sewers along the street).
Often, the point acts as a minor septic tank, receiving and storing sewer waste from the home for several days, even weeks.
Where is it located? The answer is better understood if the purpose is clear. It's placed away from the home to prevent the entry of sewerage gas into the home drainage system, which could lead to smells and other unpleasant effects.
The size of the manholes depends on the number of branching drains connected to it. There should be enough room to access the disconnecting trap for drain inspection and routine cleaning. Some people use entrance covers with open grating, which serves as an air inlet, and others prefer airtight covers.
If the disconnecting chamber is in an isolated position, the lid is probably cast iron with a grating that serves a means of ventilation for the sewage. Otherwise, the chamber comes with a ventilating pipe that acts as an air inlet. It rises above the ground level, where an accidental emission of gases from manholes won't become a nuisance.
How deep can an inspection chamber be?
The depth of an inspection chamber depends on two things. The first is the usability/size of the chamber, and the second is safety. For a manhole to be compliant with building regulations, its installation has to be at a depth where it poses no risk to humans, yet still offer easy access for inspection and cleaning.
There are three types of chambers, as well as traditional brick manholes to consider:
Small inspection chambers
Small ICs made from polypropylene and are usually 300mm in diameter. It can be installed near the top of the drain or the house. It is narrow, so the manholes reach a maximum depth of 600mm.
Standard inspection chambers
At 470mm in diameter, the standard manhole provides access for cleaning and rodding. It is large enough for a child to fall into, so the maximum depth is 1200mm.
Inspection chambers deeper than 1.2m
Deep inspection chambers can reach a depth of 3m, provided it incorporates a chamber reducing ring that restricts the opening to 350mm in diameter. It often serves as an access point for drainage and pipe inspection cameras where there's a blockage.
It's unusual for a 470mm chamber to go deeper than 1.5m—rodding becomes challenging to manage at such depths.
Traditional brick manholes
Contractors can also install chambers into wide brick manholes. Benching isn't necessary, as the chamber bottom provides connection and flow channels for pipe inlets and outlets.
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Regular manholes provide access to a drain or sewer during maintenance. Contractors use it to enter the drainage system, so a typical manhole is roughly 600x900mm of any depth.
If you're looking for PVC fittings or pipes for your manhole, we have you covered. Order any of high-quality parts from our website and receive your purchase in perfect condition.
Call our office and speak to our building and drainage experts for any problems and advice on the choice of materials and regulations. We’ll answer all your burning questions and address concerns with your individual challenges.
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Manhole Base Invert Depths:
320mm Manhole Base = 185mm
320mm Manhole Riser = 140mm
470mm Manhole Base = 225mm
470mm Manhole Riser = 235mm