Which is the most effective extinguishing...

🔍 Key Concepts

• Dry chemical extinguishers work mainly by affecting the combustion process, not just by cooling or displacing oxygen • The fire tetrahedron (heat, fuel, oxygen, chemical chain reaction) and which side dry chemical most directly attacks • Difference between smothering a fire and interrupting the chemical chain reaction

💭 Think About

• Think about what makes dry chemical extinguishers especially effective on flammable liquids and electrical fires compared to water or foam • Ask yourself: does dry chemical mainly cool the fire, block oxygen, block heat, or interfere with the combustion chemistry itself? • Consider how long the extinguishing effect lasts after you stop discharging a dry chemical extinguisher

✅ Before You Answer

• Identify which option refers to the chemical chain reaction part of the fire tetrahedron • Eliminate options that mostly describe cooling or heat shielding, which are not the primary strength of dry chemical agents • Verify which method explains why a relatively small amount of powder can stop a large flame quickly and keep it from immediately re‑igniting

Which is the most effective extinguishing action of dry chemical extinguisher?

Shielding of radiant heat

The CO2 that is formed by heat

Smothering

Breaking the chain reaction