Extinguishing Agent Properties & Chemistry Flashcards

Which extinguishing agent is specifically recommended for Class K fires involving cooking oils and fats in commercial kitchens?

Answer: Wet chemical potassium acetate solution

Wet chemical agents (potassium acetate, potassium carbonate, or potassium citrate) are designed for Class K fires because they react with hot cooking oils to form a soapy foam layer via saponification.

AFFF (Aqueous Film-Forming Foam) creates a suppression layer on flammable liquid fires by which mechanism?

Answer: Forming a thin aqueous film that seals the fuel surface

AFFF works by spreading a thin aqueous film over the fuel surface that seals vapors, preventing them from reaching the flame, while also cooling the fuel with water.

What minimum temperature limitation is a critical operational concern for CO2 extinguishers during discharge?

Answer: The discharge creates temperatures as low as -110°F (-79°C) at the horn

CO2 expands rapidly during discharge, dropping to approximately -110°F (-79°C) at the horn, which can cause frostbite if the horn is held improperly during use.

Monoammonium phosphate (MAP), the active ingredient in ABC extinguishers, melts on contact with burning Class A materials. Why is this significant?

Answer: It forms a vitreous coating that seals the fuel surface and prevents re-ignition

When MAP contacts hot Class A surfaces, it melts and forms a glassy (vitreous) coating that seals oxygen away from the fuel, which is why ABC extinguishers are effective on ordinary combustibles.

Which clean agent is most widely used as a replacement for Halon 1301 in fixed suppression systems?

Answer: FM-200 (HFC-227ea)

FM-200 (HFC-227ea) is the most widely used halon alternative for total-flooding applications because it has zero ozone depletion potential and extinguishes fires at low concentrations.

Which dry chemical extinguishing agent is considered the most effective pound-for-pound on Class B flammable liquid fires?

Answer: Potassium bicarbonate (Purple-K)

Potassium bicarbonate (Purple-K) is approximately twice as effective as sodium bicarbonate on Class B fires because potassium ions are more efficient at interrupting combustion chain reactions.

The 'saponification' reaction relevant to Class K extinguisher agents describes which chemical process?

Answer: Alkaline solution reacting with fatty acid oils to form soap and glycerol

Saponification is the reaction between the alkaline wet chemical agent and the fatty acid cooking oils to form a soap-like emulsion that blankets the surface and prevents vapor release.