Choosing the Right Manhole Cover for your Application
This simple guideline will provide you with explanations on how you can determine the type of manhole cover required for different applications: from light duty manhole covers for pedestrian use, all the way to super-heavy duty covers which will be suitable for airports, and sea ports.
Why do we use manhole covers ?
Manhole covers are an extremely important part of all infra-structure projetcs (underground utility networks). These services could be as simple as septic tank, or as complicated as a municiplal sewer network, and pumping stations.
A. First, we have to determine the “duty”, or how much each cover is supposed to handle – load wise.
The diagram below explains the duty required for each cover around the house. The cover closest to the house will only handle “light duty” as only pedestrians will use that area, while the cover on the street is expected to bear the weight of a car, and therefore will need to be of “heavy duty”.
More on loading capacity at the bottom of this guide.
B. Next: determine the size
Manhole covers are measured based on their clear opening dimensions. This is the size that is left when the cover is removed from the frame, as shown below:
The clear opening is equivalent to the size of your chamber access opening.
As far as the shape is concerned, a round chamber opening will require a round- shaped manhole cover. Likewise, the same goes for a square or rectangular chamber openings.
C. Type of covers: now, it’s time to determine the type of manhole covers you want around your house. You can choose:
1. A solid-top cover, which means that the top of the cover is visable (checkers, writing).
2. A recessed, or in-fill cover, which allows you put tile on top of the cover to match the surrounding area.
3. A sealed cover: a sealant between the cover and the frame prevents ground liquids from seeping through the cover.
4. A cover with a locking mechanisim.
Note: sealed and locked covers are covered extensively in a separate technical paper, which can be found on our web site.
More on Load bearing capacity:
Below is an excerpt from the European standard BS EN 124 indicating the design load with the corresponding area of installation:
|Class||Max. weight load (tonnes)||Uses|
|A15||1.5||Very light duty for pedestrian areas like gardens, patios and driveways|
|B125||12.5||Domestic driveway thresholds for family cars, vans and 4x4s|
|C250||25||Lightly trafficked roads and small private car parks|
|D400||40||Main roads, highways and high traffic areas like public car parks|
|E600||60||Industrial estates, loading bays and cargo handling yards|
|F900||90||Docks and airports, extreme heavy duty applications|
The function of a manhole cover is only as good as how it’s selected and the way it is installed.
Please contact us if you have any doubts about your selection and installation. Saudi Cast provides superior customer support by offering made-to-order manhole cover to ensure all the requirements are met.
For more information on Saudi Cast’s manhole cover features in our previous articles:
Part 1: Sealing and Locking features (http://www.saudicast.com/manhole_cover_features_part1/) and
Part 2: Other features of the manhole cover (http://www.saudicast.com/features-of-a-saudi-cast-manhole-cover-part-2/)
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