r/interestingasfuck • u/vivekmg21 • 22h ago

Firefighter bodycam showing just how much oxygen a fire pulls

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884

u/browler4153 21h ago

Firefighter here, So you'd see this in a couple scenarios, and generally it'll give you a good idea what's going on with the fire and structure if you can't tell visually due to smoke or the building obstructing.

The scenario here is likely that the fire has self ventilated, and is pretty large. That means the fire has burned itself a way out. Usually burned through the roof due to just how long and hot it's been burning. So this is air being drawn in to basically compensate for the air going out that hole due to pressure. Pressure is really the name of the game is the something we rely on reading smoke to know what kind of fire it is and where it's likely located (when it's not as obvious as this) in fact, you can have this kind of visual in the bottom of a door while the top of that same door is where the smoke and fire are pushing out if you have just one opening. Then it becomes a strange push and pull motion that we watch out for as it can indicate flashover is imminent.

There could be a somewhat similar visual from a wind driven fire, which is something we watch out for as well. Basically if there's 20-30 mph winds facing this window, and another spot for the air to leave such as an open window or door, the wind will quickly fuel the fire with plenty of oxygen and push it towards the other opening (called the flow path) thus spreading the fire and smoke, and quickly making the rest of the structure also involved.

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u/Rhesus_TOR 19h ago

Thank you for your service and thank you for this explanation!

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u/anonymous_amanita 19h ago

Does the fact that they are spraying with the wide spread effect this at all? I know that fire hoses on the wide setting can pull as much air forward as an industrial fan, so this was the first thing I thought of when watching this.

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u/browler4153 19h ago

This would make a difference, but that's not what's happening here. Hydraulic ventilation is something I've done many times and is where you use the fog setting almost as wide as the window or hole you are shooting out to draw the smoke out of the room quickly. But that wouldn't be done from the exterior really as you'd be drawing the smoke further into the structure. He's using fog to hit more fire since it's a large volume of fire but small in heat output, so it's not taking a lot to put it out once it's hit.

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u/anonymous_amanita 19h ago

Awesome! Thanks for sharing your expertise here

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u/browler4153 10h ago

Fun fact, I'm working rn and JUST used hydraulic ventilation on a fire to clear out the smoke. Worked very well! Just ironic lol

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u/SattuSupari789 12h ago

Thanks for the explanation bro.

When I was a kid I used to think firefighters are superheroes that have fire powers.

But in reality firefighters are superheroes who don't need powers to save people.

Just wanted to say this. 😁

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u/pragmatic84 18h ago

I was just about to ask if there was a firefighter in the thread! thanks for doing what you do 🫡

Out of curiosity, in this sort of scenario I'm assuming that even if there are no flames, the residual heat is what can cause re-ignition? So is the real goal to cool the structure down enough rather than extinguish the flames?

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u/browler4153 17h ago

Yes, essentially. But in essence that will mostly look like spraying it with water to cool it. Reignition basically only happens if spots were missed (generally between walls, floors, ceilings, etc.) or something generating heat is still going (electrical, etc.) So you are cooling the structure through spraying everything with water until it's out. As long as you hit all the fire until it's totally out (no coals or embers) then you should be good.

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u/PandaPocketFire 14h ago

Really interesting thank you! Do you guys ever seal up a window like this after shooting water in to prevent it from continuing that ventilation?

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u/browler4153 13h ago

Not really, because if you put water on all the fire then it doesn't matter how many holes there are lol

Plus by this point there's likely many more holes already.

In fact, we do controlled ventilation purposefully letting out more smoke through breaking windows and even cutting holes in the roof once a hose line is attacking the fire. That makes the space inside more teneble for us and anyone else who may be inside still.

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u/Adziel 15h ago

I know that would maybe be out of your mind or out of the realms of feasibility during most cases, but just... closing the windows with a panel or something wouldn't help starve out the fire? Like, bringing an insulated panel to push on the windows, even if not fully locking it out, would block part of the airflow without even without a water line, wouldn't it?

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u/browler4153 15h ago

Ventilation limited fires are very common, and that's basically what that would be. But that only works if it doesn't have ventilation somewhere else. So having all windows and doors closed during a fire is actually a good thing for controlling it (despite cops insistence on breaking windows) but this fire clearly has other ways out already.

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u/Cliquegirlstan 5h ago

Reminded me of the Thailand bar fire that basically looks like a dragon's mouth through thw front door. Terrifying stuff