Identify three signs that may indicate flashover is imminent.

Identify three signs that may indicate flashover is imminent.

• A. Rapid temperature drop, flames in lower layer, clear air.
• B. Decrease in heat, sparse smoke, and low humidity.
• C. Rapid temperature rise, rollover of flames in the upper layer, and dense, black smoke with rapidly decreasing visibility.
• D. Strong wind, loud creaking, humidity increase.

Answer: (C)

When flashover is about to happen, the fire’s behavior changes in a way you can recognize with three clear signs. First, you’ll see a rapid rise in temperature inside the space, as heat builds quickly and the environment becomes increasingly hot to the touch or feel in the airway. Second, you may observe a rollover—flames moving across the ceiling as the hot gases at the upper layer ignite, signaling the upper layer is reaching ignition temperatures. Third, the smoke becomes dense and black, with visibility dropping rapidly, indicating very hot, fuel-rich gases and heavy particulate loading in the upper layer. These signs together point to an extremely dangerous transition about to occur, requiring immediate action and restraint in interior operations. The other scenarios don’t fit flashover indicators: a rapid temperature drop points to cooling rather than a heat buildup; a decrease in heat with sparse smoke suggests a less intense or ventilated fire; and strong wind with creaking and humidity changes aren’t reliable predictors of an imminent flashover.

When flashover is about to happen, the fire’s behavior changes in a way you can recognize with three clear signs. First, you’ll see a rapid rise in temperature inside the space, as heat builds quickly and the environment becomes increasingly hot to the touch or feel in the airway. Second, you may observe a rollover—flames moving across the ceiling as the hot gases at the upper layer ignite, signaling the upper layer is reaching ignition temperatures. Third, the smoke becomes dense and black, with visibility dropping rapidly, indicating very hot, fuel-rich gases and heavy particulate loading in the upper layer.

These signs together point to an extremely dangerous transition about to occur, requiring immediate action and restraint in interior operations. The other scenarios don’t fit flashover indicators: a rapid temperature drop points to cooling rather than a heat buildup; a decrease in heat with sparse smoke suggests a less intense or ventilated fire; and strong wind with creaking and humidity changes aren’t reliable predictors of an imminent flashover.