This is a video clip from training in an acquired structure.

At the start of the video we can see two cameras on the left side, positioned with the firefighters in the second compartment next to the fire compartment.

The normal camera in the bottom shows that the visibility is very bad but the top thermal camera gives good orientation and ability to assess smoke conditions.

On the right side there are two cameras positioned against the entry to the second compartment, behind the firefighters.

Video breakdown

At 3 seconds

The door is opened to the fire compartment and the nozzle operator starts to cool the smoke and heat coming out with a straight stream in the ceiling.

The stream hits a surface in the ceiling and breaks up into droplets which cool the smoke on their way out to the sides and down.

The stream also creates a cold surface in the ceiling that prevents offgasing as long as it is cold, and further cools the smoke passing under it.

At 9 seconds

The nozzle operator has achieved good smoke cooling in the entire second compartment. The smoke flowing above the firefighters heads against the entry point behind them is cooler and safer.

If the objective in this training was to make that space safe, the door to the fire compartment should be closed as soon as possible. And the firefighter could also spray water over all the ceiling and wall surfaces to make sure they are cold and wet to increase that safety.

At 13 seconds

The firefighters stops to apply water. But the smoke continuous to flow from the fire compartment and it reheats the space above and behind the firefighters.

At 23 seconds

10 seconds after the application of water stops, the second compartment is again too hot and potentially dangerous.

Smoke cooling is probably only temporary.

In this example the firefighter only cooled the smoke outside of the fire compartment, to make that space temporarily safe for the firefighters to be in.

But the fire compartment is probably not affected by this action unless water is actually directed in through the opening. The outlet flow in the ceiling moves away from the fire and it pushes all the cooled smoke and steam towards the opening.

Unless we can actually pinpoint water in through the opening to a fire compartment, we should assume that it will not suppress the fire in any permanent way.

All the cooling outside of the fire compartment is thus probably very temporary. Maintaining the effect  requires a rapid reapplication with bursts of water, or a continuous flow, to maintain the smoke cold and mixed with steam.

Smoke cooling is critical!

Despite the temporary effect, smoke cooling is still critical for firefighters to be able to advance to a position where the hot surfaces in the fire compartment can be cooled.

Smoke cooling is primarily an enabler for surface cooling, which is the ultimate goal at fire suppression.

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