Which extinguishing agent is effective on Class B and C fires, but has limited use on Class A fires?

Carbon dioxide is effective on Class B and C fires due to its properties of displacing oxygen and suppressing combustion. Class B fires involve flammable liquids like gasoline or oil, and Class C fires involve electrical equipment. Since carbon dioxide does not conduct electricity and does not leave a residue, it is ideal for dousing these types of fires.

However, its effectiveness on Class A fires, which include ordinary combustibles such as wood, paper, and textiles, is limited. This is because Class A fires require a cooling agent to lower the temperature below the ignition point, which carbon dioxide does not provide. Instead, the gas simply displaces the oxygen around a fire without cooling the material involved, which may allow for reignition once the CO2 is exhausted. Therefore, while carbon dioxide is a versatile agent for certain fire classes, its limited utility in managing Class A fires underscores its specific application within fire safety protocols.