The atmosphere is mostly non-combustible nitrogen which makes it so the air doesn't explode or chain react like that

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.

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Because the flame doesn't only need oxygen. It also needs fuel to react with that oxygen and it needs the reaction of the fuel with the oxygen to release energy overall.

When you are burning something in the air, you're burning something -- that is, a fuel. The reason all the nearby stuff doesn't catch on fire as soon as you strike a match is that all of the nearby stuff doesn't react with oxygen in the air in a way that releases energy unless it gets hot enough, and it isn't hot enough. Of course, if it's close enough to a flame, then it too can burn because the flame is heating it up to a temperature where it will react with the atmosphere.

A flame is the result of combustion and it needs a fuel and an oxidizer.

The oxidizer is usually oxygen and there the atmosphere is 21% oxygen.

The rest of the atmosphere 78% nitrogen 1% argon and 0.04% other gases. Neither nitrogen or argon can be the fuel and burn with oxygen.

If we list the other gases in how common the are until we get one that can burn: Carbon dioxide, Neon, Helium and Methane.

Methane is the most common gas in the atmosphere that works as a fuel and its concentration is 0.000187% That is simply not enough to sustain combustion and even if it was possible you only use need a bit less the 2/3x the amount of oxygen. The result is 0.0005% of all atmospheric oxygen will be used up when all methane has combusted.

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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.

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Actually, fire needs 4 things:

• oxygen
• fuel
• heat
• chemical reaction

Remove any of these elements, and ignition cannot occur.

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.

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.

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

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?

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.