Extinguishing Agent Properties & Chemistry Flashcards

What is the primary extinguishing mechanism of ABC dry chemical agents such as monoammonium phosphate?

Answer: Interrupting the chemical chain reaction of combustion

ABC dry chemical agents interrupt the free-radical chain reaction in the flame, which is the primary mechanism by which they extinguish fires.

Which extinguishing agent is electrically non-conductive and leaves virtually no residue after discharge?

Answer: Carbon dioxide (CO2)

Carbon dioxide (CO2) is electrically non-conductive and dissipates completely as a gas, leaving no residue on equipment or surfaces.

Purple-K dry chemical extinguishing agent contains which primary chemical compound?

Answer: Potassium bicarbonate

Purple-K is a potassium bicarbonate-based dry chemical agent, which is approximately twice as effective as sodium bicarbonate on Class B fires.

Carbon dioxide (CO2) extinguishes fires primarily by which two mechanisms?

Answer: Oxygen displacement and cooling

CO2 extinguishes fire by displacing oxygen (smothering) and by absorbing heat energy, providing a cooling effect on the burning material.

Halon 1211 (bromochlorodifluoromethane) is classified as what type of extinguishing agent?

Answer: Halogenated agent

Halon 1211 is a halogenated (halocarbon) agent that extinguishes fire by chemically interrupting the combustion chain reaction.

What is the approximate specific gravity of carbon dioxide gas compared to air at standard conditions?

Answer: 1.5 (heavier than air)

CO2 has a specific gravity of approximately 1.5 relative to air, which causes it to settle at low points and displace oxygen effectively in enclosed spaces.

Sodium bicarbonate dry chemical is rated for use on which fire classes?

Answer: Class B and C fires only

Sodium bicarbonate (ordinary dry chemical) is rated for Class B (flammable liquids) and Class C (energized electrical) fires but is not effective on Class A fires.