Viewing a single comment thread. View all comments

NameUnavail t1_je9zlun wrote

Because a flame needs two things to burn:

Oxygen and fuel. And the rest of the stuff that's in the air (mostly nitrogen) doesn't work as fuel, so the air by itself can't burn.

19

GalFisk t1_jea53kd wrote

Which is also the reason why atmospheres of almost pure fuel, such as methane, don't combust - there's no oxygen there. Without oxygen, all our energetic fuels, such as gas, oil, wood and coal, would be completely useless.

10

Red__M_M t1_jean4l4 wrote

I learned this playing with potato guns. There is an optimal fuel level beyond which the power quickly declines to zero.

The solution, of course, was to saturate the chamber with fuel and close it. Then I injected oxygen. Worked like a charm.

2

GalFisk t1_jeao113 wrote

Pure oxygen? I never did play around with that, but I did make an arduino-powered fuel meter which would inject precisely the right amount of propane. That was a big improvement from "spray and pray", even though I did get quite good at it with butane.

1

Red__M_M t1_jeaun5e wrote

I modified a pen torch to work with a valve stem and mounted one of those to the chamber. Of course, I only used the oxygen cylinder of the torch.

I like your solution. Can you post a picture?

2

its-a-throw-away_ t1_jeag2ao wrote

Actually, fire needs 4 things:

  • oxygen
  • fuel
  • heat
  • chemical reaction

Remove any of these elements, and ignition cannot occur.

2

Coomb t1_jeau7mi wrote

It's more accurate to say that fire is the chemical reaction than it is to say that fire needs a chemical reaction.

0

its-a-throw-away_ t1_jeb5m89 wrote

The old fire triangle was changed to the fire "tetrahedron" which includes "chemical reaction" after chemical extinguishants were developed that solely disrupt the ability for oxygen and fuel to combine quickly enough to sustain fire. These extinguishants do not displace oxygen or fuel, or absorb heat, but inhibit the reaction itself as a catalyst's functional opposite.

1