Types of Manholes

 

What Are Manholes?

Manholes are underground structures that give access to cables, pipes, wires, and sewers. They also come in handy when maintaining or repairing these things.

The purpose of these covers is pretty obvious from their name – they serve as an opening from a manhole into an underground chamber that contains one or more utility lines.

Whether or not you know it, you’ve likely seen manholes in your daily life. Manhole covers are used to cover small underground access points that allow workers to travel from one point to another safely.

Although manhole covers are often forgotten about once they’re put into place, they are crucial for everyday safety and underground utility maintenance.

How Are The Manholes Made?

In general, manholes are manufactured from concrete. However, several different types differ depending on their purpose. Here’s an overview: Round – The most common type is round and has an internal diameter of about 15 inches (38cm).

They’re relatively small compared to other types, making them easy to handle during construction work. If you’re renovating your house, you might need larger ones for future use.

Usually, cast iron or ductile iron (steel) manhole is made by machine casting methods. The machines are as follows: sand-making machine, melting machine, pouring machine, and surfacing-grinding machine. They are placed in a row for production.

According to different specifications, the standard manhole is divided into two types: ordinary type with lifting frame and special type without lifting frame; also divided into dry pipes and wet pipes.

The dry pipes watercourse has no contact with the underground water. In contrast, the wet pipes have the watercourse in contact with underground water.

In addition, the manhole can be produced in different shapes such as round, oval, square, polygonal (such as a triangle), etc.

Different Types Of Manholes

You might think that all manholes are essentially similar; after all, they’re essentially just holes in a road. But, as it turns out, there are several different types of manholes for various reasons—and even just in terms of location. Based on the depth of a manhole, it has been categorized into three parts- shallow, normal & deep.

1. Shallow Manhole

A manhole having a depth of up to 90 cm is termed a shallow manhole. It serves as an inspection chamber at the start of a branch sewer, and the cover is light in weight.

2. Normal Manhole

A manhole with a depth of 90-150 cm is categorized as a normal manhole, and it is covered with a heavy cover.

3. Deep Manhole

A deep manhole has a depth greater than 150 cm. The size of a deep manhole is also big, according to the size of the facility. It is also facilitated with a permanent ladder.

Purpose Of Manhole

The different types of manholes have different purposes.

1. Sanitary Sewer Manhole

It provides the entry or exit to a sanitary sewer.

2. Storm Sewer (also known as catch basin) manhole

It is used to enter or exit a storm sewer. The opening is designed with a lip on which water can flow, so rain will naturally wash any contamination into the storm sewer instead of entering buildings.

3. Utility Manhole

Also called fire protection system manhole. It is used for locating buried utility lines such as gas, water, cable TV, telephone systems, and others for maintenance work.

Utilities generally don’t place their own service pipes in underground concrete vaults—this allows customers access to these facilities if maintenance or repair is needed while providing physical security.