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Which gas is primarily used in fire extinguishers to put out electrical fires?
Carbon dioxide
Oxygen
Nitrogen
Hydrogen
Carbon dioxide
Carbon dioxide (CO2) is the primary agent used in fire extinguishers for electrical fires because it is an electrically non-conductive, chemically inert gas. It effectively suppresses fire by displacing oxygen, which is essential for combustion, without damaging sensitive electrical components.
Carbon dioxide (CO2) is the primary agent used in fire extinguishers for electrical fires because it is an electrically non-conductive, chemically inert gas. It effectively suppresses fire by displacing oxygen, which is essential for combustion, without damaging sensitive electrical components.
Think of it like placing a heavy, non-conductive blanket over a candle; you are starving the fire of the 'air' it needs to breathe while ensuring you don't get electrocuted by touching the flames.
CO2: Cut Off Oxygen
C+O2тАЛтЖТCO2тАЛ тАФ The basic combustion reaction, where removing O2тАЛ halts the process
╬ФH=mтЛЕcтЛЕ╬ФT тАФ Represents the heat absorption (cooling) during the phase change of CO2
COтВВ works via the principle of oxygen displacement and cooling. When released from a pressurized cylinder, liquid COтВВ expands rapidly into a gas, absorbing significant heat (Joule-Thomson effect). By creating a blanket of dense, non-combustible gas, it reduces the oxygen concentration below the critical threshold required to sustain the fire (O2тАЛ<15%) without leaving any messy residue.
CO2 is non-conductive, making it safe for electrical equipment.
It leaves no residue, protecting delicate circuitry from damage.
It is heavier than air, allowing it to settle over the fire base.
It is ineffective on Class D fires (combustible metals).
Non-corrosive and non-conductive
Does not leave a residue
Effective on Class B and Class C fires
Risk of frostbite during discharge
Limited effectiveness in windy outdoor areas
Risk of asphyxiation in confined, small spaces
Server rooms and data centers
Electrical laboratories and control rooms
The density of CO2 is roughly 1.5 times that of air.
Oxygen (Option B) is an oxidizer and accelerates combustion.
Nitrogen (Option C) is sometimes used in clean agent systems but is less common for portable manual fire extinguishers.
Hydrogen (Option D) is highly flammable and would explode rather than extinguish a fire.
A is correct тАФ Carbon dioxide is the preferred agent for electrical fires as it does not conduct electricity and displaces the oxygen required for combustion.
Always remember that CO2 extinguishers are for Class C (electrical) and Class B (flammable liquids) fires; never use water on electrical fires to avoid the risk of electrocution.
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