Which extinguishing system is best suited for commercial cooking hoods, plenums, ducts, and associated cooking appliances?

• A. Dry Chemical (ABC)
• B. Clean Agent
• C. Wet Chemical (Class K)
• D. Water Mist

Answer: (C)

Fats and oils in commercial cooking fires behave differently and often involve the vented path through hoods and ducts. To control these fires effectively, you need an extinguishing system designed specifically for cooking oils and capable of reaching through the hood, plenums, and ductwork. Wet chemical extinguishing systems (Class K) are made for this environment. The wet chemical agent saponifies fats, turning oils into a soapy layer that cools the oil and forms a barrier that helps prevent reignition. Because the system is installed within the hood and throughout the ductwork, it can deliver agent directly where grease fires occur, including inside ducts, which is critical for these scenarios. After discharge, the area and system require recharging and cleaning due to the oily residue. Other options don’t target grease fires in vented cooking spaces as effectively: they may be less effective on oil fires, leave difficult residues, or lack ductwork reach needed for commercial kitchens.