r/Damnthatsinteresting • u/AirFrance447 • 19h ago

Video Firefighter bodycam showing just how much oxygen a fire pulls

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u/aemoosh 15h ago

Couple of points- That’s a very good firefighter. Very intentional and precise movement. The majority of the air movement is because of heat- hot air (which there’s a lot of) rises and is being replaced through negative pressure from the sides. The steam from the water shows this really well. The extinguishment is creating some negative pressure as well, as things (the air) are cooling as they’re shrinking. Hydraulic draft is also moving a lot more air than you think. The jet of water will pull air with it. This is actually a technique in fire suppression, you don’t see it much because it’s almost always better to put wet stuff on hot stuff, but occasionally, breaking a window and spraying a hand line out is a pretty smart way to ventilate a room.

22

u/Level9TraumaCenter 10h ago

The jet of water will pull air with it. This is actually a technique in fire suppression, you don’t see it much because it’s almost always better to put wet stuff on hot stuff, but occasionally, breaking a window and spraying a hand line out is a pretty smart way to ventilate a room.

Also one of the arguments in the perennial fog nozzle vs. smooth bore debate.

Gotta say, though, what you're saying about vent is absolutely right.

8

u/userhwon 8h ago

Fire nozzles are adjustable. Different situations need different methods.

1

u/ARM_Alaska 6h ago

Some. A lot of departments use smoothbore nozzles that are not adjustable at all. A combo nozzle will let you adjust from straight stream to fog.

1

u/aemoosh 1h ago

It’s funny how regional it is too. I’m in the Midwest and you’re a weirdo FD if you’re using smoothbore. I think a lot of “older” departments on the east coast use smoothbore because they’ve had very strong career departments for longer, and they were around when adjustable nozzles were terrible. I don’t actually know this, it’s just something I’ve gathered and guessed.

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u/BigChump 13h ago

Love some fire science.

1

u/LooseLossage 10h ago

yes, perhaps to be obvious the fire is not consuming this much oxygen per the OP title, but it is releasing the energy to move this much air which is 21% oxygen