🔍 Key Concepts

• Fire tetrahedron (fuel, heat, oxygen, chemical chain reaction) and how different agents attack it • Characteristics of Class B fires (flammable liquids and gases) • Primary action of dry chemical extinguishing agents compared with foam, CO₂, and water

💭 Think About

• Think about which part of the fire tetrahedron dry chemical powder is specifically designed to interrupt, beyond just covering the surface • Compare how foam works on a fuel spill versus how dry chemical acts in a vapor-rich environment • Ask yourself: does dry chemical mainly remove heat, remove oxygen, or interfere with the combustion process in another way?

✅ Before You Answer

• Confirm what water is mainly used for (which method) and eliminate that option • Confirm what foam and CO₂ are mainly used for and which methods they rely on (smothering vs. oxygen dilution) • Identify which option is most directly linked to stopping the chemical chain reaction of combustion, rather than just covering or cooling the fuel