Which type of firefighting foam is commonly used by ARFF vehicles?

Alcohol-resistant Aqueous Film-Forming Foam (AFFF) is the most commonly used type of firefighting foam by Airport Rescue and Firefighting (ARFF) vehicles due to its effectiveness in suppressing flammable liquid fires. This foam is designed to create a barrier between the fuel and the air, making it particularly suitable for aviation fires, which often involve jet fuels and other hydrocarbons.

What sets alcohol-resistant AFFF apart is its ability to handle fires involving polar solvents, such as alcohols, which can mix with water and become more challenging to extinguish with traditional foams. The alcohol-resistant formulation ensures that the foam remains effective even when in contact with these substances, providing a critical advantage in an airport environment where speed and efficiency are paramount in fire suppression.

The other options do not possess the same level of effectiveness in aviation fire scenarios: dry chemical foam is typically used for different types of fires and may not spread effectively over burning fuels; water-based foams can dilute in the presence of alcohols instead of forming a protective film; and protein-based foams, while effective, do not offer the same quick-dissipating film formation as AFFF, particularly in the presence of alcohols. Therefore, the unique properties of