Thread: Question on Fire Point
05-09-2007, 10:42 PM #1
Question on Fire Point
First I have tried the search function on the site and I get this... Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 83 bytes) in /mnt/sites/forums.firehouse.com/htdocs/includes/functions.php on line 51
So if this has been asked please don't slam me.
My Question is does anyone know of a chart, web page, book and or personal study for the Fire Point or Auto Ignition Point of Wood, Paper, and Corrugated Card Board; there is alot of info on Liquid Flash Points but I'm having a hard time finding any info on the Wood products, I remember a book that one of my instructor's had from an arson investigation class, a long time ago, that had some of this info but like I said I'm not finding any thing useful and Google didn't help either. Any help would be appreciated.
05-10-2007, 03:42 AM #2
All I could find is the auto-ignition temperature of wood - 572 degrees F.Just someone trying to help! (And by the way....Thanks for YOUR help!)
Aggressive does not have to equal stupid.
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05-10-2007, 07:37 AM #3
I have some spread sheets that might help. They cover a wide range of products. Drop me an E-Mail and I can send them to you.
05-10-2007, 09:24 AM #4
Thank you (thefirenut) and I have sent the email (sepalmer)
05-10-2007, 01:34 PM #5
- Join Date
- Jul 1999
- Flanders, NJ
In order to understand the iginiion of solid materials, you have to know more than simply the ignition temperature.
First of all, flashpoint is the temperature of a liquid fuel, theoretically corresponding to the lower flammable limit of the its evaporated vapor and the point of piloted ignition ( Quintiere 1997). It is a term lmiited soley to liquid materials. Firepoint is also a term limited solely to liquid materials. Firepoint is the minimum temperature to which a liquid must be heated in a standardized apparatus (key point) so that sustained combustion results when a small pilot flame is applied (Friedman 1989). When discussing the ignition of solid fules such as wood products, these terms must never be used.
Autoignition is the initiation of fire by chemical process inherent int he material (Quintiere) or spontaneous ignition, generally of the type resulting from the external heating by a hot surface or compression (Friedman). The autoignition temperature is the minimum temperatureat which a mixture of fuel and an oxidizer can propagate a flame without the aid of a pilot (Quintiere).
What is an important to understand about these values is that they are all established in standardized testing in a laboratory. They are useful as rellative values in comparing materials. You may find vairations, however, in actual field situations.
It is also important to keep in mind that the ignition temperature is only one aspect of the ignition of solid materials that must be considered. The amount of actual heat energy applied (heat flux) is equally as important. Another aspect that must be considered is the form of the material. Stacked flat cardboard boxes will be much more difficult to ignite and sustain combustion than would empty cubed cardboard boxes. A wood crib would be more susceptible to ignition than the same amount of wood stacked and bundled. The reason is the surface to mass ration. The more surface area that is exposed to the air (and the heat energy), the easier that material will be to ignite. The ignition properties of thick cellulosic fuel is drastically different than thin cellulosic fuels.
In practice, the autoignition temperature of a material will be slightly higher than the material's listed ignition temperature. This temperature can vary widely, based on factors such as moisture content, contaminants and additives, age, concentration, etc.
To evaluate whether a particular ignition source is competent, you must consider all of the above factors, not just the ignition (or autoignition) temperature.
For further reading on this, and any other subject you can dream of, try this link: http://fire.nist.gov/bfrlpubs/
05-10-2007, 02:16 PM #6
Sorry for using the term Fire Point so loosely, I should be careful when posting around people that are way smarter that me
I understand the that Soon after active pyrolysis begins, combustible gases typically evolve rapidly enough to support gas-phase combustion. However, combustion will occur only if there is a pilot flame or some other source of energy sufficient to cause piloted ignition. If no such pilot is present, the surface must be heated to a much higher temperature before Autoignition occurs and what I was looking for was the general test lab, rule of thumb or ballpark information if you will. I received an E-Mail from (sepalmer) and he provided me several charts that was what I was looking for so thanks for all the input.
05-10-2007, 03:27 PM #7
- Join Date
- Jul 1999
- Flanders, NJ
Autoignition is one of the most misunderstood phenomenon in the field of combustion. I posted my explanation not only for you, but for anyone reading this who may also not fully understand it.
Good luck on your studies.
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