What is a confined space?

What is a confined space?  Well it isn’t what everyone may think…

They don’t have to be small – they can be massive [think as big as a ships hold!], they can even be open like a building site trench, and you may not even be doing any task in the space.


What is a confined space?

Answer these two questions. Is it fully or partially enclosed? and, does it have one of the 5 specified risks?

“Confined spaces” must be fully or partially enclosed, entrances can be at the top, the side or even from the bottom, and they may be above or below ground.


Consider the gases that could be inside…

  • Are the gases lighter or heavier than air?
  • Are the team being lowered down in to, or
  • climbing in to the deadly hazard?

You wouldn’t climb in to a big bath of water and expect to be able to breathe. An open trench, vat, tank or silo – is just like a bath, but instead of water – it’s full of a non breathable gas.

Some of the more common gases you can’t even see, smell or taste. You don’t know its affecting you, until it’s too late.


Is your Confined Space fully or partially enclosed?

These can be fully or partially enclosed - entrances can be from above, underneath or from the side

To be defined as a “Confined space” – the space must be fully or partially enclosed. Most people just see the entrances as from the top like manholes to go down in to a pit, tank or sewer. This could even be an open trench like on a building site…


Is it full of gas that is heavier than air? You wouldn’t climb in to a big bath of water (or gas in this case) and expect to be able to breathe! The same is true if the gas is lighter than air and you climb up in to it… [The best case scenario – you may fall out of the hole in to fresh air!]

Entrances are often at the side… but the gas inside could still be the same buoyancy as air – waiting to fill the team’s lungs.

You need to know the dangers, monitor the atmosphere, ventilate the space and supply respiratory protection.


How are the team getting in…

How are we getting them out in an emergency?


Specified Risks of a confined space

Regulation 1 of Confined Space Regulations states that a “specified risk” means a risk of:

Confined space specified risk - Fire or explosion

Fire or explosion

Serious injury to any person at work arising from a fire or explosion.

  • Flammable substances and Oxygen enrichment
  • Risk of fire or explosion from:
    • Oxygen cylinders e.g. welding equipment
    • Airborne flammable contaminates
    • Leaks from adjoining plant not effectively isolated


Confined space specified risk - risk of suffocation from being immersed in a free flowing solidFree flowing solids

The asphyxiation of any person at work arising from a free flowing solid or the inability to reach a respirable environment due to entrapment by a free flowing solid.

  • Solid materials that can flow
    • Can submerge a person
    • Can trap a person

‘Free flowing solids’ means, any substance consisting of solid particles and which is of, or is capable of being in, a flowing or running consistency, and includes flour, grain sugar, sand or similar material.


Confined space specified risk - flooding - risk of drowning in a liquid


The drowning of any person at work arising from an increase in the level of a liquid.

  • Ingress or presence of liquid
    • Liquids can flow into and collect in low level confined spaces
    • Can be corrosive, toxic or harmful


Specified risk - toxic gas, fume, vapour or lack of oxygen

Toxic gas, fumes or vapour, or a lack of oxygen

The loss of consciousness or asphyxiation of any person at work arising from gas, fume, vapour or the lack of oxygen.

Toxic Gas, Fume or Vapour

  • Fumes from previous process or storage
  • Sludge
  • Build up in sewers, service hatches (man holes), contaminated ground
  • Leak from behind vessel lining
  • Welding, cutting, lead lining, brush and spray painting
  • Moulding using grip adhesives or solvents
  • Products of combustion
  • Hot work taking place outside the space
  • Plant failure causing build-up


Oxygen Deficiency

  • Inert gas purging
  • Natural occurring biological processes consuming oxygen
  • Fermentation in sealed silos
  • Leaving vessels closed for long periods
  • Carbon dioxide produced when limestone chippings get wet
  • Burning operations
  • Displacement of air when pipe
  • freezing
  • Depletion of oxygen in poorly ventilated space


Confined space specified risk - heat exhaustion


The loss of consciousness of any person at work arising from an increase in body temperature.

  • Presence of excessive heat
    • Dangerous rise in body core temperature
    • Incorrect use of PPE could raise body core temperature
  • Working in heat – In hot and humid atmospheres, the body temperature is regulated to a large extent by the cooling action produced by the evaporation of sweat. The body temperature can only be maintained within safe limits so long as the
    surrounding air is capable of providing adequate evaporation of the sweat on a human body. This will depend on the air’s moisture level.


Heat exhaustion

Symptoms include:

  • Exhaustion with restlessness
  • Headache, dizziness, nausea
  • Muscular cramps in lower limbs and abdomen through salt deficiency
  • Pale face, cold/clammy skin
  • Fast/shallow breathing and a rapid weak pulse

In such circumstances, withdraw all the team to a cooler environment; give drinks and seek medical aid.


Heat Stroke

Symptoms include:

  • Headache
  • Dizziness
  • Feeling hot and restless
  • Flushed
  • Dry skin
  • Full and bounding pulse, noisy breathing

In such circumstances, withdraw all the team: cool off urgently and seek medical aid urgently.


Other Hazards of a Confined Space

  • Human hazards i.e. tripping, stumbling
  • Too many people within a confined space
  • Obstructions within a confined space
  • Biological i.e. sewers, septic tanks
  • Cross contamination of liquids and gases
  • Rats and other infestations
  • Control of Substances Hazardous to Health
  • Electrical
  • Mechanical
  • Noise
  • Dust
  • The general public
  • Working at height


Confined Space Rescue Planning (P.E.T.S)


Emergency Planning – Before any entry is made, arrangements must be made to deal with any emergency eventuality that may occur based on an adequate risk assessment without putting the rescuers unnecessarily at risk.


Equipment – Including rescue equipment must be appropriate in view of any likely emergency identified in the risk assessment. All equipment must be checked and tested and findings recorded on a regular basis. Equipment will include fire and first aid equipment.


Training – Persons involved in any confined space entry, or who could be involved with any foreseeable rescue attempt, must be trained to a standard appropriate to all identifiable risk, i.e. resuscitation.


Confined Space Supervisor – The supervisor (top person) is the link to the outside and plays a vital role in any confined space emergency situation. It is the supervisors responsibility to initiate the emergency arrangements.


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