What is the purpose of dry chemical extinguishing agents on ARFF vehicles?

• A. To suppress electrical fires
• B. To supplement foam during fuel fires
• C. To cool down metal surfaces
• D. To enhance visibility during smoke

Answer: (B)

The purpose of dry chemical extinguishing agents on Aircraft Rescue and Firefighting (ARFF) vehicles is primarily to supplement foam during fuel fires. Dry chemical agents, such as sodium bicarbonate or potassium bicarbonate, are effective at interrupting the chemical reactions that sustain combustion when used in conjunction with foam. The foam helps to provide a protective blanket over the fuel, preventing ignition and suppressing vapors, while the dry chemical can quickly put out flames and protect the environment from potential fire hazards.

In the context of ARFF operations, fuel fires are a significant risk, especially around aircraft, where flammable liquids can be present. The combination of dry chemicals and foam enhances overall firefighting effectiveness in these scenarios.

While dry chemicals can also suppress certain types of electrical fires, their main role in an ARFF context is as a supplementary agent to foam for controlling flammable liquid incidents. Cooling metal surfaces or enhancing visibility during smoke is not their intended purpose within the operational strategies of ARFF.