15th April, 2019

The Definition Of A Confined Space And 20 Examples

In simple terms, a confined space is any enclosed place with limited access and increased risks due to that. Confined spaces can be above or below ground. They also don't need to be entirely enclosed. They might only be partially enclosed, but enclosed enough that means risk is increased.

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Every year, people die and are seriously injured in confined spaces. We recently wrote about what makes confined spaces dangerous places. But it is not always obvious when you are working in a confined space. In this blog post, we are taking it back to basics and looking at what exactly a confined space is, with definitions and examples.

Confined space definition

In simple terms, a confined space is any enclosed place with limited access and increased risks due to that. Confined spaces can be above or below ground. They also don't need to be entirely enclosed. They might only be partially enclosed, but enclosed enough that means risk is increased.

Increased risks in confined spaces can be because of restricted access and exit. It might be difficult to get in and out. This increases risks because, if something was to happen, it will be hard for you to escape. It will also mean it is difficult for someone to rescue you. Those outside the space might not be able to see those inside the space. This makes it difficult to communicate when you need help, or problems occur.

Access and communication aren't the only hazards in confined spaces. Because the space is enclosed, there can be issues with ventilation. Hazardous substances can get trapped in the space and cause the atmosphere to become unsafe. There may not be enough oxygen present, and not enough ventilation to provide fresh oxygen when needed (oxygen has been used up through breathing or other activities within the confined space). Confined spaces can also quickly flood with water or other materials.

Confined spaces are not usually intended for occupancy by people, but during maintenance work or other activities, entry in the space may be required. A confined space permit to work will often be used to control entry, due to the high-risk nature of the work, and the hazards it can present.

Find out more about the hazards in confined spaces in our blog post 7 hazards that make confined spaces dangerous places.

The definition of a confined space varies slightly depending on where you look. But it all boils down to the same thing. An enclosed place with increased risks. Where better to look for an official definition of confined spaces than the confined space regulations themselves...

“confined space” means any place, including any chamber, tank, vat, silo, pit, trench, pipe, sewer, flue, well or other similar space in which, by virtue of its enclosed nature, there arises a reasonably foreseeable specified risk;

So that's the official definition. Any place which, because of its enclosed nature, there is a reasonably foreseeable risk. It also includes a few helpful examples, like chambers, tanks, vats, silos and pits. We will expand on a few more examples shortly.

The HSE website also includes a useful definition, which means the same thing, but uses slightly different wording...

A confined space is a place which is substantially enclosed (though not always entirely), and where serious injury can occur from hazardous substances or conditions within the space or nearby (e.g. lack of oxygen).

If we are looking for a confined space then, we are looking for a place that is enclosed (not always entirely). It will have restricted access. Entry to this place would be at an increased risk because of the access issues, or hazardous substances or conditions within the space.

confined space tank
A confined space is a place which is substantially enclosed

Examples of confined spaces

Now we know what a confined space is, by definition. Maybe you have come up with some examples yourself. Here are 20 examples of confined spaces:

  1. Manholes this is usually an opening or access to a confined space, which is also a confined space itself!
  2. Sewers underground pipes and tunnel systems carrying drainage water and waste matter.
  3. Storage tanks and vats containers used to hold liquids and gases.
  4. Excavations often for temporary access or construction below ground, excavations can quickly flood or collapse.
  5. Trenches as above, trenches are usually dug for short term work, but can often be enclosed and form confined spaces with restricted access.
  6. Pits vehicle inspection pits, industrial pits and mining pits.
  7. Tunnels these underground passageways are often what springs to mind when thinking if a confined space.
  8. Lift and access shafts a vertical shaft that often extends below ground but even at the floors above ground it still forms a confined space.
  9. Ducts conduits, passages and pipe systems used in heating, ventilation, and air conditioning.
  10. Pipes move liquids and gases from one area to another, both vertically and horizontally (often at a gradient).
  11. Chambers may be fully or partially enclosed and sealed, but can often be confined spaces.
  12. Silos fully or partially enclosed structures for storing bulk (often loose) materials like grain.
  13. Flues found at the end of duct, pipe, or openings.
  14. Boilers and boiler rooms, usually in larger industrial applications can be confined spaces where entry is required.
  15. Vaults underground or enclosed storage area accessed by a maintenance hole.
  16. Hoppers storage container and dispenser via a chute.
  17. Wells a vertical excavation or structure, e.g. a water well.
  18. Cargo holds in ships access to holds is restricted by a large hatch at the top.
  19. Unventilated areas and rooms in buildings particularly below ground level but can be found on any floor.
  20. Vessels and voids spaces that may need to be occasionally accessed for maintenance, repairs and during construction.

Remember, confined spaces are dangerous places. The Confined Spaces Regulations apply to all work within confined spaces and must be applied.

If you need help preparing your safe systems of work, we have health and safety documents to help you. Download the confined space risk assessment template to plan the work, the confined space permit to work to control the work, and the confined space toolbox talk to raise awareness.

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This article was written by Emma at HASpod. Emma has over 10 years experience in health and safety and BSc (Hons) Construction Management. She is NEBOSH qualified and Tech IOSH.

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