# Flame height?

## Main Question or Discussion Point

Just curious: Is there a way to calculate flame height given the material being burnt and the area of flame output hole (for example a lighter with adjustable flame height)?

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I would expect it to depend on the internal pressure in the case of the lighter. This would explain why the flame of a lighter gets shorter as it empties. The velocity at which the butane escapes from the lighter will depend on the pressure of the butane canister and the size of the hole it is escaping from, once you have the exit velocity you'd probably need some number representing how long it takes the butane molecule to burn, on average, then you can just do d=v*t to get an idea of how tall the flame will be.

Danger
Gold Member
The nature of the fuel itself, and the air/fuel ratio should be of significance as well. I guess that the fuel part is covered by knowing how long a molecule takes to burn, as dice mentioned. As for the air... consider the difference in effect of an acetylene torch at constant pressure with differing amounts of oxygen fed in.

Danger said:
As for the air... consider the difference in effect of an acetylene torch at constant pressure with differing amounts of oxygen fed in.
Um... not all of us have acetylene torches to play around with. Not that I'd turn one down, mind you

Danger
Gold Member
If they still make Bunsen burners the way they did when I was in school, you can get the same demonstration by adjusting the air intake on the bottom.