Which of the following extinguishing agents is not recommended for Class "A" fires?

• A. Water
• B. Foam
• C. Carbon dioxide
• D. Chemical dry powder

Answer: (C)

For Class "A" fires, which involve common combustible materials such as wood, paper, and textiles, the recommended extinguishing agents effectively cool and suppress the fire. Water is commonly used because it effectively reduces the temperature of the burning materials. Foam is also appropriate as it can smother flames and cool down the fire.

Carbon dioxide, however, is not recommended for Class "A" fires. While it is effective against Class "B" fires (like flammable liquids) and electrical fires, its lack of cooling capacity makes it less useful against Class "A" materials. Carbon dioxide works by displacing oxygen, which isn't as effective in extinguishing fires fueled by solids, as it does not address the underlying heat and does not cool the combustible materials.

Chemical dry powders can be versatile and effective for multiple classes of fire, including Class "A," as they smother the fire and interrupt the combustion process.

In summary, the ineffectiveness of carbon dioxide in cooling and addressing the specific combustion characteristics of Class "A" fires makes it unsuitable compared to the other agents listed.