A ‘confined space’ refers to an area that is enclosed with limited access, but is large enough for a person to enter to perform tasks. This can make it dangerous to work in. Most confined spaces are not designed for personnel to work within on a daily basis. Confined spaces are usually designed to store materials, enclose a process or transport materials. Inspection, repair and cleanup can produce physical and chemical hazards within these spaces. Examples of hazards within combined spaces include unbreathable gases (which may be invisible), submersion in liquids or free flowing grain and risk of explosion. Those working in confined spaces must receive specific training. Those entering and working within confined spaces must have permits to do so, and, only enter when it is safe to do so. They must only remain as long as necessary for the work to be done. These permits set out the work to be done, precautions to be taken and a record of all foreseeable risks. It may be necessary to wear a respirator, but even so, the space should only be entered if it is safe. Precautions to be taken when working in these spaces include testing breathable air quality, ensuring adequate ventilation, observation of workers and an emergency rescue plan to. Examples of confined spaces include the inside of a boiler, a fluid storage tank, cargo holds, pump rooms, pressure vessels, ballast tanks and an underground electric vault.
Air Quality: Because the space is small, the amount of breathable air may be constricted. A safe concentration of oxygen would be 19.5% and 23.5% of the total atmosphere. Even if the space is found to have breathable air, a hazard can develop during operations which may release toxic gas or vapour which may then be accidently ignited. Toxic substances may arise when coating or sandblasting in or around a confined space. If work is being carried out in a pipline, personnel should be aware of the other connecting pipes and any possible hazards that may be imposed. As well as testing for oxygen, testing should be carried out for flammable atmospheres. Air quality can present hazards to health.
Stored Products: There may be entrapment due to the unexpected free flowing of liquid or solids. PPE may help in these cases. PPE can include body protection, foot and head protection, gas meter, ear and eye protection and breathing apparatus. Certain chemicals stored in spaces can cause headache and nausea.
Noise: Not only can this cause hearing loss, but also hinder hearing other personnel trying to communicate.
Temperature: There may be loss of consciousness due to rise in body temperature. At very cold temperatures, hypothermia can occur.
Isolation: Communications with outside personal should not be hindered in any way. A person(s) should be on permanent guard outside the confined spaced and be in constant contact by visual or radio means. The standby person(s) should not have any other duties, should not be distracted and be trained in how to react in an emergency. They will be the immediate contact in the emergency escape plan.
Size of space: All confined spaces will differ in size. Some can be as small as 18 inches in diameter, through which is may be very difficult to move or administer life saving equipment.
Flammable atmospheres: The amount of oxygen in the air and flammable gas makes the confined space an explosive risk. If a source of ignition like an electric tool is introduced into a confined flammable space then the result may be an explosion. There may have to be forced ventilation in confined spaces. Not ventilation with pure oxygen, because if there is a fire, oxygen will cause things to burn quicker. Ventilation with normal air should be done.
General precautions for entry into confined spaces (depending on the hazards) can include an emergency breathing set, portable radio, light source, retrieval harness and a gas detector capable of monitoring oxygen and hydrocarbon.
As well as adherence to the Health and Safety at Work Act 1974, there is the Confined Spaces Regulations 1997 which applies where the assessment identifies risks of serious injury within these spaces. There is also the Management of Health and Safety at Work Regulations 1999, which requires employers and the self-employed to carry out a suitable risk assessment for the purposes of deciding what measures are necessary for safe working.