26 HEALTH AND SANITATION
Safety in enclosed spaces
By
Chris Coetzee , health and safety consultant , OHSS
Plumbers may be exposed to enclosures with limited openings such as drains , sewers , tanks and silos as confined spaces . These are often places that are not usually entered by people but may need to be during maintenance work or inspections .
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During construction work , some areas may become confined spaces due to the work being carried out , for example within trenches , unventilated rooms or building voids . Let ’ s look at seven hazards that arise .
A ‘ confined space ’ is defined as an enclosed space which :
• Is large enough and so configured that an employee can enter with their whole body and perform assigned work
• Has limited or restricted means for entry or exit ( some examples are tanks , vessels , silos , storage bins , hoppers , vaults , pits and diked areas )
• Is not designed for continuous employee occupancy
A confined space is also defined as having one or more of the following characteristics :
• Contains or has a known potential to contain a hazardous atmosphere
• Contains a material with the potential for engulfment of an entrant
• Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or a floor which slopes downward or tapers to a smaller cross-section
• Contains any other recognised serious safety or health hazards
1 . Lack of oxygen Oxygen can be removed from the atmosphere within a confined space through naturally occurring reactions . A reaction between certain soils and the oxygen , or groundwater and chalk or limestone can produce carbon dioxide which displaces oxygen . Rust forming inside tanks can also create a lack of oxygen .
Great care needs to be taken when working in confined spaces .
2 . Gases , fumes and vapours Poisonous gases and fumes can build up within confined spaces , especially where there is a lack of ventilation . Deadly gases can leak into the confined space , for example through a burst gas pipe or from contaminated land . Or they may be created from the work being carried out , such as welding , adhesives or paint fumes . Without extraction or ventilation , these gases and fumes can create a toxic atmosphere within the confined space .
3 . Flooding Liquids can quickly flood the confined space , particularly in drainage or sewer work , trapping and potentially drowning those within . And it ' s not just liquids you should worry about . Solids can also flood confined spaces , for example in trench collapses , with those within the trench at the risk of being trapped or buried . Confined spaces can be small , so flooding can occur in a matter of seconds , leaving no time to escape .
4 . Dust Dust can build up within confined spaces , either naturally occurring or through the activity being carried out , such as drilling or grinding . Excessive dust inhalation causes respiratory problems , and hazardous dust can be fatal . Dust build-up can also increase fire / explosion risk , especially where there is a lack of ventilation .
5 . Fire and explosions Flammable vapours , liquids , gases and dust within the confined space can all increase the risk of fire and explosions . The risk is increased further where any hot works or tools which can spark are used within the confined space . Remember how lack of oxygen was number one on our list ? Well , too much oxygen is also bad . Excessive oxygen levels increase the risk of fire and explosions .
6 . Temperature Strenuous work , hot work or naturally occurring hot conditions can lead to a dangerous increase in body temperature . This can quickly become a problem within confined spaces that are hard to escape from at the best of times . Heat can rapidly rise due to the enclosed nature of a confined space . This can lead to heatstroke , exhaustion and collapse .
7 . Access restrictions Confined spaces are also dangerous because they can be difficult to access . This makes escape difficult and also hinders any emergency
www . plumbingafrica . co . za @ plumbingonline @ plumbingonline @ PlumbingAfricaOnline April 2025 Volume 31 I Number 02