Considering a fire needs fuel and oxygen and heat to continue burning, is it possible to put out a fire by lowering the ambient temperature below a certain point?
I am not a physicist, nor do I play one on TV. But I think the answer is yes. IIRC, fire requires fuel, heat and oxygen, and the removal of any one is enough to extinguish it. But I think you’d need a pretty low temp.
Here we go: The Fire Triangle. Looks like the best way of removing heat is, um, dousng the fire with water.
Again the boards ask what I wondered for ages but didn’t bother asking myself.
So if a match was frozen, would it refuse to light? Or if you brought a burning candle from one room to another that was identical in all aspects except temperature, would it burn out more quickly?
I always assumed that once something was alight, the burning would probably heat up the rest of the unlit material as it approached and you’d continue to have combustion.
If a match were frozen, maybe it would break apart when you tried to strike it?
For a fire already started, sounds like you need a radical drop in temp, not just the onset of a cold snap.
for a match to ignite it has to go above its ignition temperature. it could have an coldness that the amount of heat you supplied, like through friction in striking, would not heat it above that point.
if the candle was brought into a room which froze the molten wax and that in the wick then it would go out.
your assumption is correct for how things stay burning.
if you removed enough heat it would go out.
though how you remove heat in a practical sense also might affect another element. if you used water to cool a fire you would also deprive the fire of oxygen where the water is.
you could put a candle in a deep freezer with a video camera and an oxygen sensor and if the candle went out while there was still enough oxygen to support combustion then that would be an answer.
Back in grad school we hosted a superbowl party one January in Wisconsin. We knew from a few weeks earlier that the charcoal grill just would not stay lit when it was bone-ass cold outside. So for the Superbowl party, we bought a bottle of oxygen from a welding shop, hooked up a regulator and set up a trickle-feed via a copper tube into the bottom of the charcoal.
We had great difficulty NOT burning our food to a crisp.
I areas where forest fires are sometimes a problem the newscasters often say lower temperatures will help suppress the fire. I don’t recall any explanation.
forest fires are really the liquids and solids of trees being turned into a combustible vapor before it is burned. that takes energy in the form of heat for the fire to be self sustaining. less of this takes place when the air temperature is lower because more heat has to come from the fire itself.
also in warmer temperatures any water in the vegetation might be less, this water has to be evaporated before the material can burn.
When you blow on a match or candle they go out. You are not depriving the fire of O2, like with water but it still goes out. You are cooling the fire below ignition temperature.
I went on a short fire safety course at the Heathrow Airport fire station. The firefighter who ran the theory session said that, contrary to popular belief, the main action of dousing a fire with water was to lower the temperature of the fuel and not to exclude oxygen.
this thread reminds me of how the economy of San Francisco was stalled after the earthquake & fire because all the safes were red-hot and due to their mass would take a long time to cool. The paper money inside them was in perfectly good condition, but if the safes were opened and air let in, the fire triange would be complete and the money would burst into flames.
I knew a “researcher” that was working on a proposal to use magnetic fields to inhibit/stop fires.
Forest Gump Voice : And thats all I have to say about that.
I have to question this. Like most flammable substances, paper has an auto-ignition temperature - the link says something like 450 degress F. Compare that to the temperature of red-hot steel, which this link says is around 1000 degrees. And if you raise the temperature of paper to anything like that of red-hot steel, it will decompose even if (say because of lack of oxygen) it can’t burn.
There’s also the point that if you have a hot safe with good money inside, you need merely pour water on it until it cools enough to handle - should take at most an hour or so.
How about fire-resistant safes? Don’t they have ceramic layers/other mechanisms to somehow limit what the internal temperature can get to for a few hours of high outside temperatures?
If you open the door, you suddenly raise the inside temperature above the autoignition temperature, and BLAZE
- soot on the roof of my freezer
- risk if setting refrigerants (usually flammable) on fire - perhaps explosively
One of those dont-try-this-at-home experiments eh?
R
Would it? Interesting question. Or would it burn less bright?
should be easy to test though.
I’ve done fire fighting courses in the past.
At one, our instructor mentioned fires in roading tar. Apparently a way they can be extinguished is by adding more tar. Using water is very messy and can muck up the surface, even of the bits that aren’t on fire. You can’t remove the fuel, so you reduce the temperature by adding cold tar.
As mentioned by ticker, water works for most fires by lowering the temperature of the fuel. But sometimes you don’t want to use water because it has to go somewhere once it’s been squirted onto the fire and you may not want it to. Also, sometimes it will just carry the burning fuel away on top of it.
Breaking one side of the (heat, fuel, oxygen) triangle will extinguish a fire.
Yes, you can freeze out a fire. That is largely what a CO[sub]2[/sub] extinguisher does. The effect of the heat absorption is greater than the oxygen deprivation from the dry ice snow, but both mechanisms are in play.