Most Chemical Safety Guide

All You Need To Know About Working in a Confined Space


Confined spaces refers to largely enclosed areas or spaces not designed for people, where workers can enter and perform certain jobs. Confined spaces have restricted means of entry or exit, with high risk to workers of explosion, fire, asphyxiation, loss of consciousness or drowning. Confined spaces may include pits, tunnels, duct work, equipment housings, manholes, tanks, vessels, storage bins, silos, vaults, hoppers, and pipelines. OSHA defines "permit-required confined space" as a confined space that has one or more of the characteristics: containing potential hazardous materials and atmosphere, containing material with potential to entrant or engulf, has floors that sloping downward or inward or walls converging inwards, areas that can asphyxiate or trap an entrant, and areas with other health hazard such as exposed wires, heat stress, and unguarded machinery.


The hazards associated with working on confined spaces include toxic atmosphere, oxygen deficiency, oxygen enrichment, flammable or explosive atmospheres, flowing liquid or free-flowing solids, and excessive heat. An area is considered to have a toxic atmosphere because of different hazardous substances caused by disturbance of sludge or other deposits, leftovers from previous storage or processing, presence of flames or fire within the space, seepage from improperly isolated plant, or formation during work operation that are carried out in space. A toxic atmosphere causes acute and chronic effects on health, as well as unconsciousness, impairment of judgement and death. Read for example this post:


Oxygen deficiency can be caused by air gas displacement, chemical reactions such as burning or rusting of chemicals, and steel surfaces absorb air especially for damp areas. On the other hand, oxygen enrichment or excessive amount of oxygen is brought about by combustible materials, resulting in increased risk of fire or explosion. A flammable atmosphere may cause explosion, which results in hot gas expulsion and structure disintegration. The presence of free-flowing liquids may cause suffocation, drowning, burns and other injuries, while free-flowing solids in powder can be distributed in a confined space causing asphyxiation.


The essential elements to be considered when drawing up a safe system of work in a confined space include  training, competence, supervision and suitability, permit-to-work procedure,  gas purging and ventilation, dangerous residues, respiratory protective equipment, mechanical, electrical and process isolation, monitoring and testing of the atmosphere, safe use of equipment, communications, access and egress, explosive or flammable atmospheres and presence of combustible materials. Safety data sheets(SDS) is a document containing important information about the potential hazards (fire, reactivity, environmental and health) and how to be able to work safely with the chemical product.


Safety Data Sheet from contains detailed information on the use, handling, storage and emergency procedures which are relevant to the hazards of a specific material, in order to have focal point for development of complete program to prevent health and safety issues.