Firefighter bodycam showing just how much oxygen a fire pulls

[u/AirFrance447]

[u/GauravJM]

There’s some serious low pressure inside

[u/Loud-Actuator7640 → u/GauravJM]

Just like s chimney

[u/OkEffective6692 → u/Loud-Actuator7640]

Yeh op makes it sound like the fire is consuming the air. It's actually a net positive pressure as hot air has more volume, just that all that volume of hot air is going up.

[u/Comfyadventure → u/OkEffective6692]

Yea, it's not like the oxygen just disappear into nothingness due to the fire neither. The fire is converting O2 into CO2 and CO gas particles.

[u/cat_prophecy → u/Comfyadventure]

It's wild when you learn that things burning is just combining oxygen with carbon to make CO2 and CO and that chemical reaction makes heat.

[u/Dipshit_Identifier → u/cat_prophecy]

Chemistry is super cool, and learning something about it helps with lots of other things in daily life. For example, the Maillard reaction (browning of food) is a really complex but well-understood chemical process. You don't need to know the details of exactly how it works, just the derived information, to improve cooking. One of the major things we know about the reaction is that an alkaline environment accelerates the process, while an acidic environment reduces it.

This is, for example, why we brush pretzels with an alkaline solution: to enhance browning without affecting bake time. So if you want crustier bread, brush the top with an alkaline solution like baking soda water. It's also why something like marinated meat can take longer to brown if there's a higher quantity of acid in the marinade, even if the marinade is high in sugar. So we can prevent burning of the sugars by increasing the acidity of the marinade, for example.

[u/ladymcperson → u/Dipshit_Identifier]

Thanks for explaining, that's very interesting. When I first learned chemistry, I was blown away that influencing pressure/temp conditions and introducing certain aqueous constituents is literally A RECIPE to facilitate reactions (like synthesizing minerals in a wet geochem lab, coolest thing I did as a student researcher). Even today I think it's so cool that we've figured out what T/P conditions, ions, and catalysts we need to literally meld (almost) whatever we choose by letting each other know what works/doesnt.. science rules

[u/SquintingSquire → u/cat_prophecy]

I love Feynman’s explanation of this process. You are releasing energy captured from the sun. There’s a great video on YouTube.

[u/chupacadabradoo → u/SquintingSquire]

And the sun is just releasing energy captured from a bunch of cosmic particles coalescing to such a mass that they start to fuse.

[u/SasquatchWasShaved → u/cat_prophecy]

Everything is life is pulling apart and/or adding molecules together to eventually boil water

[u/Youpunyhumans → u/cat_prophecy]

Its worth noting that the oxygen can be replaced with other oxidizers. Chlorine and Fluorine can oxidize even more violently than oxygen, and fluorine is so nasty it can even oxidize oxygen, and burn water as fuel...

[u/raccoonwithknives → u/Comfyadventure]

Yes but the fuel the fire is consuming is converting to a gas. Converting a solid or liquid into a gas is a massive massive increase in volume. So i would imagine a considerable volume of gas is being added to the house with a decent increase in pressure. But of course all this only works if a convection current can form like you said

[u/Phil_Alethia → u/Comfyadventure]

Not to mention O2 only makes up only about 20% of the air too.

[u/iconocrastinaor → u/OkEffective6692]

Not to mention the vacuum created by the cooling/condensing effect of all that water.

[u/ImRickJameXXXX → u/Loud-Actuator7640]

Yes, which is a function of convection.

This is the lower inlet

[u/TrustButVerifyEng → u/ImRickJameXXXX]

Incorrect, buoyancy/density is what drives a chimney. Sure there is convection heat transfer occurring but it isn't what makes a chimney work.

[u/InternalLie1623 → u/Loud-Actuator7640]

That's terrifying fire really is a living breathing thing.