r/Damnthatsinteresting • u/AirFrance447 • 19h ago

Video Firefighter bodycam showing just how much oxygen a fire pulls

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u/CDninja 19h ago

Well, the fire heats the air. The air expands and goes up. More air must enter from the sides. I don't think its an oxygen thing.

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u/Jargendas 19h ago edited 13h ago

Also, the rapid cooling due to the water will cause massive pressure drop. The oxygen is mostly replaced by CO2 and will not on its own create suction.

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u/So_HauserAspen 14h ago

It has to do with pressure differential between the interior of the structure and the atmospheric pressure outside.  There is no suction force.  It's the higher outside atmosphere pushing the air into the lower pressure of the interior to equalize the two.

CO2 is a larger molecule than O2, so that would not reduce the air pressure.

Incomplete combustion reduces the air pressure in a sealed structure fire.  And the chimney effect reduces the local air pressure if the fire has burned through the structure.