What is a Confined Space?
A confined space is an enclosed space where there is a risk of death or serious injury from hazardous substances or dangerous conditions (e.g. lack of oxygen).
A confined space has one or more of the following characteristics:
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Limited access or egress
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The space contains known or potentially hazardous substances and / or atmospheres
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The space is not intended for continuous working
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Conditions of engulfment or entrapment may exist or develop.
Some confined spaces are obvious such as storage tanks, silos, enclosed drains and sewers. However, others may be less obvious, such as vats, ductwork, unventilated / poorly ventilated rooms and open-topped chambers
Principle Hazards of a Confined Space
Dangers can arise in confined spaces due to the following:
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Lack of oxygen - Low oxygen levels may occur through – engulfment; rust formation; chemical reaction between soil and oxygen; groundwater reacting with chalk and limestone to produce carbon dioxide and displacing normal air; or decomposition of organic matter.
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Fire and/or explosions
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Toxic substances - Poisonous gas, fume or vapour may accumulate in the space from surrounding ground, may enter from connection pipes, or may build up in connected vessels etc.
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Physical hazards are amplified - Examples include noise, extreme temperatures, burn hazards, engulfment hazards, mechanical hazards, slips/trips or falls, electrocution and moving machinery.
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Residues left in tank/vessel - These may give off gas, fume or vapour.
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Dust - This may be present in high concentrations e.g. flour silos.
Legal Duties
Employers are legally required to carry out a risk assessment under the Management of Health and Safety at Work Regulations 1999. For work in confined spaces this means identifying the hazards present, assessing the risks and determining what precautions to take. The assessment will normally include consideration of:
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The task
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The working environment
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Working materials and tools
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The suitability of those carrying out the tasks
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Arrangements for emergency rescue.
If your risk assessment identifies serious risk of injury from working in confined spaces, the Confined Spaces Regulations 1997 apply. The key requirements of the regulations are:
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Avoid entering the confined space e.g. by doing the work from the outside
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If entry is unavoidable, adopt a safe system of work
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Develop and implement suitable emergency procedures prior to commencing work.
Avoiding Entry to a Confined Space
You must consider whether the work can be done in another way so that entry or work in a confined space can be avoided. Good planning and adopting a different approach can reduce the need for confined space working.
Safe Systems of Work
You must have a safe system of work in place for work in a confined space. The safe system of work, and any precautions identified must be developed and put into practice. Everyone involved must be properly instructed to ensure they know what to do and how to do it safely.
The results of your risk assessment will help to identify the necessary precautions to reduce the risk of injury.
Risk Assessment
A suitable and sufficient risk assessment must be carried out by a competent person prior to work in a confined space. The risk assessment should question the following:
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Is entry to the space essential?
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Can the job be undertaken from outside the confined space?
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What hazardous substances may be encountered?
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What hazards may be encountered?
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What control measures could be adopted?
Where possible, keep hazards out of a confined space. For example, petrol or diesel engines should never be used inside the space, substances which emit solvent vapours should not be used, and burning processes should be undertaken outside of the space and the articles then lowered into place.
The work should be carried out from outside a confined space where possible. For example, cameras may be used to inspect inside confined spaces, or cleaning or sampling may be undertaken using tools from outside the space.
* See Appendix 2.