What is a confined space?

You might imagine a confined space to be small and completely enclosed, but this is not the case. A hazardous confined space is any size of partially or fully enclosed space which offers the potential for build up of hazardous substances or dangerous conditions.

Where are you likely to find confined spaces?

Confined spaces may be storage tanks, silos enclosed drains or sewers, chambers within machinery such as wind turbines, combustion chambers or ductwork. They may also be less closed-off spaces, such as poorly ventilated rooms, open topped chambers, vats or other vessels. Anywhere offering the possibility of gas accumulation or oxygen starvation can be regarded as a confined space.

What hazards might be encountered?

In many confined spaces other processes going on can cause production of gases, such as the biological breakdown processes in septic systems which create hydrogen sulphide. Alternatively, some materials can react with oxygen, using it up in the reaction and causing a deficit. An example of this would be rust formation where iron, water and oxygen react to form iron oxide.

Accumulations or depletions of gas can lead to extreme hazards in a number of ways.

• Explosive conditions, where gas acts as an accelerant to fire.
• Asphyxiation – from oxygen deprivation or gases such as carbon monoxide which prevent the body from using oxygen.
• Poisoning – many gases, including excess oxygen can lead to unconsciousness/nerve damage and worse.
• Lung damage

Confined spaces may also be difficult to exit in an emergency and may be at height. The space could be at risk of flooding, by gases or liquids, it may be dark and inaccessible and possibly located in a remote area.

What should you do first?

A full assessment of the confined space is essential to identify all hazards present as well as an assessment of the need to enter at all. Can work be carried out from outside the space? Can it be modified so entry is unnecessary? Can remote equipment be used? If entry cannot be avoided, always consider mitigation of hazards first. Can the space be ventilated or drained?

It is then important to plan for every eventuality. This includes arranging for someone to remain outside the confined space to communicate with those inside and to set in motion any emergency recovery plans.

Anticipate all hazards involved before entry.

Your risk assessment should include identification of any gases involved and a full understanding of the likely results if these are inhaled. Remember that any work carried out may in fact create new hazards. Identify all the precautions you will need to take to reduce injury risk and exactly how rescue will be carried out in the event it is required.