Posted on 04/09/2012 2:13:42 PM PDT by Lady Lucky
I've been asked one of those questions so basic that you never know 'til you're asked, that you really don't know. So I tried answers.com and all those other reasonable places and still can't answer. I figure there are enough smart people on FR to improve my chances. Question: When a fire starts, why does it flare up with a sudden burst of energy that is more intense than the subsequent flames? What's going on there? Why does it not kindle gradually, appear first feeble and then grow to its regular intensity?
It has to do with the quantity of combustable fuel available. Many fuels are more combustable when they are hot and are off-gassing. However, while these are more common in modern usage, they are not the typical case.
Try lighting a candle ... no huge flare. Light leaves, an old oil lantern, paper, charcoal with wooden matches.
If you have an explosive mixture of fuel (propane BBQ grill, lighter fluid, phospohorus - well, then things are a little more interesting, aren’t they?
Magic.
Initially, it’s a hot physical attraction. And then you get to know each other.
In movies, it can happen the other way. You know, the friends first thingy. You’ve known each other for years, suddenly, and one day a general warmth progresses into a slow smolder and eventually flames.
Fuel, heat and oxygen makes fire. My guess is the flare up is the oxygen being sucked in towards the heat and fuel. And as I said, it’s a guess.
Thats a very interesting question..hmmm. Thats my usual response when I do not have a clue.
Pure guess does it have something to do with oxygen? I mean there is more oxygen available initially...?
Well yeah, it's ALL magic. :)
Throw a few gallons of diesel on there and get the party started!!!!!
(do not play with gasoline)
My guess: the heat needed/used to start the fire, whether friction or another flame, volatilizes some part of the fuel that you are trying to light. This will be invisible/vapor but when some part of it starts to burn, the rest “flashes”.
There is maker recognition that the flare might have to start in a windy or cold environment, so the initial fuel contains extra factors to quickly establish a proper operation temperature for those environments —the rest of the stick will already be somewhat pre-warmed and therefore doesn’t have the need for the extra chemical factors.
That’s a guess.
There is maker recognition that the flare might have to start in a windy or cold environment, so the initial fuel contains extra factors to quickly establish a proper operation temperature for those environments —the rest of the stick will already be somewhat pre-warmed and therefore doesn’t have the need for the extra chemical factors.
That’s a guess.
It has been years since my last chemistry class so some of the details may be wrong but here goes:
Wood, for example, out-gasses when it is heated. As the wood heats up, it releases flammable gasses. The fire you see is actually the gasses burning, not the wood.
Most flammable things are like this. The oxygen in the air is too diluted to have the combustion you are talking about so it takes the object you are trying to burn the need to ‘heat’ up to cause combustion.
Some chemical reactions, however, work much faster. Put some potassium in water, for example, and you have a fast chemical reaction of the potassium grabbing the oxygen’s extra electron then splitting the bond so the hydrogen atom is released which is highly flammable.
It could have something to do with more still air, containing about 20% oxygen, surrounding the initial flare. Just my guess. It could be the rush of oxygen that is needed for fire.
It could have something to do with more still air, containing about 20% oxygen, surrounding the initial flare. Just my guess. It could be the rush of oxygen that is needed for fire.
Actually it has strangely to do with globular warming. When all the little bits come to temperance there is an understanding between them all to get the job done before quitting time aka flash point. So they arrange plans in committee in order to be more effective in their combustible relationships and therefore the end reslut.
In other cases, if there is an available inrush of oxygen when the fire first starts like opening a door or window, then the oxygen flow stabilizes.
In the case of self-ignition, like rotting grass/weeds/oily rags, there is not real flare but a gradual warming, then a flame starts.
The study of fire is really neat and centers around 4 major issues: available oxygen, available fuel, temperature, and ability for a pyrolitic chain reaction to allow for the oxidation of the available fuels. Knock out any one of the 4 items and the fire goes out. So, fire suppression centers on cooling, removing or smothering fuel, reducing temperature, or somehow interupting the chain reaction at the molecular level.
When you start a fire, the maximum surface area of the combustible material is exposed to the oxygen. After a time the burned material acts as a insulator between the oxygen in the air and the fuel. That is why a log fire needs to be stirred and prodded - to knock off the ash and carbon on the outside to expose the unburned wood.
Fumes from all that gasoline.
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