Which chemical is commonly used in portable extinguishers for Class C fires?

Portable extinguishers designated for Class C fires, which involve electrical equipment, commonly use carbon dioxide (CO2) as the extinguishing agent. CO2 is effective for Class C fires primarily because it is non-conductive, ensuring that no electrical current can travel through it, thus minimizing the risk when extinguishing fires involving live electrical circuits. Additionally, CO2 displaces oxygen in the area of the fire, which helps to smother the flames without leaving a residue that could potentially damage sensitive electrical equipment.

In contrast, other agents such as water can conduct electricity and can be hazardous in the presence of live electrical equipment. Dry chemical powders can also be effective but are typically more associated with Class B fires involving flammable liquids and solids. Foam is primarily used for Class A and B fires and is not suitable for electrical fires. Therefore, carbon dioxide is the most appropriate and safe choice for extinguishing Class C fires.