Free Republic
Browse · Search
General/Chat
Topics · Post Article

To: SargeK
Likewise at the moment of ignition, oxygen is at its maximum. It is consumed in the combustion. If the oxygen is not replaced - if the draft to the fire is restricted, the flame will diminish and maybe go out.

Then, typically, fires exist in a state of increasing starvation? If the oxygen around a fire were to be deliberately added at a steady rate, the fire would continue to flare?

41 posted on 04/09/2012 3:01:27 PM PDT by Lady Lucky (Romney, the pink slime of presidential politics.)
[ Post Reply | Private Reply | To 27 | View Replies ]


To: Lady Lucky
If the oxygen around a fire were to be deliberately added at a steady rate, the fire would continue to flare?

The rate at which a combustion reaction proceeds may be limited by the concentration of oxygen, the concentration of fuel, or the amount of available heat. When the speed of a reaction is limited by the concentration of oxygen or fuel, it can be controlled by regulating the rate at which oxygen or fuel are made available, since the faster the reaction occurs, the less oxygen or fuel will be available to it. When the speed of the reaction is limited by the amount of available heat, however, it is very unstable. The faster the reaction occurs, the more heat will be available to it; this process will often accelerate until the rate of combustion is limited either by the availability of oxygen or fuel.

Many materials are not directly flammable, but when heated will decompose into other materials that are. Often, the decomposition reactions may occur at temperatures below the ignition point of the substances produced, and may absorb a considerable amount of heat. As a consequence of this, it is entirely possible for a fire to give off substances which decompose into flammable gasses or particulates, but which lose so much heat doing so that they can accumulate without igniting. This accumulation may continue until some of the materials are hot enough that--even after decomposition--they are hot enough to auto-ignite. This will quickly heat up nearby materials which were almost--but not quite--hot enough to auto-ignite. This process will proceed very quickly until it consumes nearly all the immediately-available oxygen or fuel, whichever runs out first. Once that occurs, the rate of the reaction will be limited to the rate at which oxygen or fuel is made available to it.

55 posted on 04/09/2012 3:44:13 PM PDT by supercat (Renounce Covetousness.)
[ Post Reply | Private Reply | To 41 | View Replies ]

To: Lady Lucky

More oxygen accelerates the rate of combustion, so yes, I think you’re correct.


66 posted on 04/10/2012 5:49:07 AM PDT by SargeK
[ Post Reply | Private Reply | To 41 | View Replies ]

Free Republic
Browse · Search
General/Chat
Topics · Post Article


FreeRepublic, LLC, PO BOX 9771, FRESNO, CA 93794
FreeRepublic.com is powered by software copyright 2000-2008 John Robinson