TCFP Plans Examiner Practice Test

What is added to detergent foam to create an aqueous film that sits on top of hydrocarbon fuel spills?

1. Silicone surfactant

2. Fluorinated surfactant

3. Alkali surfactant

4. Nonionic surfactant

The correct answer is: Fluorinated surfactant

The addition of a fluorinated surfactant to detergent foam is specifically designed to create an aqueous film that effectively responds to hydrocarbon fuel spills. Fluorinated surfactants are characterized by their unique chemical properties, including a fluorinated tail that provides a high degree of surface tension reduction and the ability to spread rapidly across liquid surfaces. When a fluorinated surfactant is incorporated into firefighting foam, it forms a stable film on top of hydrocarbon fuels, which helps to suppress flammable vapors and reduces the risk of ignition. This film acts as a barrier, preventing oxygen from reaching the fuel and thus enhancing fire control and extinguishment. The hydrophobic nature of the fluorinated portion promotes excellent spreading and coverage over the spill area, which is critical in managing hydrocarbon fires effectively. In contrast, the other surfactants mentioned do not provide the same level of performance for creating the necessary protective film on hydrocarbon spills. Each of those surfactants may have their own applications, but they lack the specific properties required to form an effective aqueous film barrier on hydrocarbon fuels.