Need Some Info on Pine Trees

[PublicEducator]

My Company had recently been dispatched to a Building fire. Upon arrival, our 1st assistant chief confirmed a working Building fire. Here is the problem and question: There was a row of pine trees fairly close to the fire building that seem to be spontaniously igniting themselves. We discussed this when we returned to the station. I told my assistant that I thought that one time in fire House magazine there was an article on pine trees giving off gas that will make them ignite themselves. I have looked at my back issues but I could not found anything. Does any one have any info on this?

[RxFire]

PublicEducator -
Pine trees do not give off flammable gas. What was happening is that the heat from the structure fire was pre-heating the trees, drying out the needles on the trees to the point where they would be able to catch fire. Just think of a Christmas tree. Mature, healthy pines are fire resistant, but that doesn't mean that they won't eventually catch fire.

RxFire

------------------
I HATE spot fires!!
http://fire.nifc.nps.gov/fum/

[This message has been edited by RxFire (edited 02-01-2001).]

[Althea Forhan]

I've got to disagree there. Pine trees are extremly flamable in my expirience.Every time I go camping, It's the primary kindling.Oddly enough, the bark of the Redwood tree is flame retardent, If you don't beleive me, just try getting it to sustain a flame.

Althea

[Brat]

Live pine trees don't spontaneously ignite. The radiant heat from the structure dried out the trees and allowed the pitch to heat above the point of ignition. They burn like gas when that happens. If they don't dry out they don't burn. That is why you water your Christmas tree. Don't water it and you have the equivalent to a can of gas in you house.

[MetalMedic]

Well now, if we want to get "technical" the pine trees must heat to the point that they give off a flammable vapor before they can burn. That is basic fire behavior. Solids and liquids do not burn, they must be heated to the ignition temperature, which is when the material begins to change to a gas.



------------------
Richard Nester
Orrville (OH) Fire Dept.

[Firediver]

I was at a forest fire awhile back and saw one explode like a bomb. An old time forest fighter said that the sap in the tree gets to its boiling point, then the pressure gets to much for the tree, then booooooommmmmm!!! I thought he was jackin' me around till I saw it.

Craig Walker
Stay Low, Stay Safe...BUT GET YOU SOME!!!!!!

[pyroknight]

You beat me to the fire chemistry MetalMedic, but my .02 would be that there is an OBVIOUS difference in the flammability of evergreens vs. hardwoods. The sap or rosin in the pines, cedars, firs, etc. is very flammable (and really sticky too, ick!) and since it's a liquid will off gas more rapidly than trees that do not have sap.

[Dalmatian90]

Just to add one more item or nuance...

The sap/water in the tree is also why trees often "split" or "explode" when hit by lightning...the sap inside instantly turns to steam and blows the tree apart.