Why is it not recommended to use CO2 fire extinguishers extensively in enclosed spaces

Working Principle of CO2 Fire Extinguishers

Portable carbon dioxide (CO2) fire extinguishers work by releasing liquid CO2 under high pressure, forming a gas cloud that covers the fire source. This reduces the temperature of the flames and displaces oxygen, effectively suppressing combustion. CO2 does not leave residue or cause secondary pollution, making it ideal for electrical fires and sensitive equipment areas. The effectiveness of CO2 extinguishers relies on oxygen displacement, which presents special risks in enclosed spaces.

Safety Hazards in Enclosed Spaces

Releasing large amounts of CO2 in a confined area can rapidly reduce oxygen levels. Oxygen concentrations below 19.5% can cause dizziness, fatigue, and difficulty breathing. At concentrations below 15%, severe disorientation or unconsciousness may occur, and prolonged exposure can be life-threatening. The accumulation of CO2 gas also increases local pressure and concentration, further endangering personnel.

Using CO2 extinguishers in enclosed spaces increases operational difficulty. Gas clouds reduce visibility, and accumulated heat and smoke make navigation hazardous. The rapid cooling effect of CO2 spray may cause skin frostbite or condensation damage to sensitive equipment, increasing the risk of injuries.

Environmental Factors Affecting Fire Suppression

Confined spaces typically have poor air circulation, causing CO2 to accumulate in localized areas and reducing overall fire suppression effectiveness. Dense CO2 gas tends to settle near the floor, making breathing difficult for personnel. High-temperature fire sources interacting with cold CO2 may create local thermal stress, potentially damaging containers or piping.

Temperature and humidity within enclosed spaces also impact CO2 discharge performance. Low temperatures reduce gas expansion and shorten discharge range, extending extinguishing time. High temperatures increase cylinder pressure and recoil force, complicating safe handling and aiming during operation.

Management Guidelines for Enclosed Spaces

Using CO2 extinguishers in enclosed or semi-enclosed areas requires strict adherence to safety protocols. Oxygen monitoring equipment should be installed to track CO2 levels in real time. Personnel should evacuate the area or use breathing protection before activation. Discharge should be controlled to avoid large releases at once. Ventilation systems or automated sprinklers can assist in removing CO2 and improving fire suppression safety.

Organizations should select fire suppression methods based on risk assessment. For electrical or flammable liquid fires, CO2 extinguishers can serve as auxiliary tools but should not be the primary method in confined spaces. Training personnel on the physiological effects of CO2 and operational limitations is essential to prevent accidents.