What can lead to re-ignition after a Class K extinguishing event?

• A. The cooling film breaks down or heat sources remain.
• B. Re-ignition cannot occur after proper discharge.
• C. The extinguisher's contents are inert.
• D. The hood system being activated counts as re-ignition.

Answer: (A)

Re-ignition after a Class K extinguishing event happens when heat sources or fuel remain and the protective cooling layer created by the wet chemical agent breaks down. Class K agents work by cooling and saponifying cooking fats, forming a film over the oil that helps smother flames and slow heat transfer. If that cooling film degrades or the oil and hot surfaces stay hot, heat can transfer back to the fuel and reignite the fire even after the initial discharge. So the breakdown of the cooling film or leftover heat sources are what can lead to re-ignition.

The other ideas aren’t correct because simply discharging the extinguisher doesn’t guarantee no re-ignition, especially if heat or fuel persist. An inert extinguisher content wouldn’t provide active cooling, so it wouldn’t prevent re-ignition. And the hood system activating is part of the suppression/ventilation response, not a rekindling event.