In this Ask John we explain confined spaces and the lurking hazards. Then we answer the question… Why use gas detectors when working in confined spaces?
Confined space definition…
“An enclosed or partially enclosed space that is not intended or designed primarily for human occupancy. It is liable to have an atmosphere that contains harmful contaminants or not contain a safe oxygen level. It may have contents that could cause engulfment. It may have restricted means for entry and exit.”
Source: Worksafe
Breaking it down
A confined space is…
- An enclosed or partially-enclosed space (e.g. tanks, silos, holds, pipelines, etc).
- Designed to contain things, not people (e.g. fluids, sewerage, grains, powders, vehicles, etc).
- The atmosphere in the confined space is likely to contain contaminants that are harmful to people (e.g. carbon dioxide, carbon monoxide, chlorine, methane, etc).
- The atmosphere in the confined space is likely to contain unsafe oxygen levels (e.g. low oxygen causing unconsciousness, or high oxygen causing an explosion risk).
- It may have contents that could cause engulfment, i.e. flow over and completely cover somebody (e.g. grains, powders).
- It may have restricted means for entry and exit.
As you can see, there are numerous elements to confined space work that present possible hazards to workers. Wearing a gas detector helps mitigate some of those hazards.
The presence of harmful gas in a confined space can be exacerbated by the confined physical environment.
In confined spaces there is less dilution possible than in open spaces. And there is invariably less ventilation available in confined spaces than open spaces.
Furthermore, air quality may be compromised in confined spaces, resulting in unsafe low oxygen levels.
So, why use gas detectors in these situations?
It’s obvious really, but if you are wearing a suitable gas detector in any of those scenarios, it will raise an early alarm and make you aware of the need to evacuate.
The final point of Worksafe’s definition is also pertinent. Due to the nature of the confined space, it can take longer to make a safe exit. This makes it even more important that any gaseous or air quality hazards are notified as early as possible.
