Air exhaust fans - Confined spaces interventions

The main risks that can occur when working in confined spaces are the depletion of the oxygen rate and the presence of toxic, flammable or explosive gases. Air exhaust fans - also known as COBRA fans - are essential equipment for working in these totally or partially closed areas. 

The CATEC ® system (Certificate of Ability to Work in Confined Spaces) defines the recommendations and good practices to prevent hazards in confined spaces. Air exhaust fans are part of the measures to be adopted to work safely in these hazardous areas. 

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Interventions in confined spaces: Risks and hazards

The main risks associated with working in confined spaces are the following:

  • Risks of asphyxiation: the lack of oxygen and the accumulation of asphyxiating gases such as carbon dioxide (CO2) can lead to asphyxiation and serious illness;
  • Risk of explosion or fire: the presence of flammable gases (natural gas, butane, propane, hydrocarbon vapors) or dust can lead to fires and explosions;
  • Risk of poisoning or intoxication: exposure to chemicals or biological contaminants can lead to poisoning.

Why ventilate a confined space properly?

Ventilation of a confined space is extremely important because it allows to reduce the risks of asphyxiation, toxicity or explosion. Air exhaust fans are used to provide fresh air to the workers. Therefore, they increase the level of safety because they dilute the toxic gases or vapors that may be present and provide healthy air throughout the intervention.

For an efficient ventilation, 3 rules must be respected:

  • Prefer ventilation to extraction to take full advantage of the unit's performance;
  • Count 7.5 times the volume of the confined space to renew the indoor air;
  • The fan must be able to ventilate 20 times the volume of the room per hour.