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Fire Behavior
I'm confused, maybe somebody can help explain this. When I took my level 1 (recently) we were told roof ventilation would not increase fire intensity and on an interior entry sounding the floor while searching is what you need to do while searching in zero vis. Was just reading testing conclusions from UL and they say none of this stuff is accurate and in some cases more dangerous then helpful. While reading there were other techniques taught in level 1 that are contradicted and possibly dangerous or wrong.
steve
Replies to This Discussion
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Permalink Reply by steve hutchinson on
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They did a house burn with us and we were upstairs with this whole room engulfed and they wanted us to watch when the smoke plume started rolling over itself, we had no ventilation in place and the fire got into the attic and they told us to get out of the house. We had a hose but they were trying to show us I guess how bad it can get. Isn't it a bad place to be when the smoke plume starts rolling because maybe the room is getting ready to flash?
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Permalink Reply by captnjak on
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They probably wanted you to see how fire developes and to learn to trust your PPE. Nothing wrong with that. It's a good drill for any firefighter to experience. There should ALWAYS be a hoseline and a backup line for any of these types of drills. Live house fire burns make me very nervous and I am generally against them.
I disagree with the decision to get you out of the house. You had a charged line. Why not use it to put out the fire? That's the biggest part of the drill to me. Seeing firsthand what happens with water application is also a good learning experience. You know you can trust in the hose stream to do it's job.
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Permalink Reply by FETC on
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To become an educated aggressive firefighter.
http://community.fireengineering.com/profiles/blog/show?id=1219672%...
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they figured the fire got up in the attic and we had no overhaul gear with us and only one charged line plus we were on the second floor. We had done about 3 burns in that same room so everybody there got a chance to experience the awesome power of fire.
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That was a good article. So is it ok then to put a water stream into a thermal layered smoke ploom to allow further hose advance into a structure, or does the disruption of the layers make conditions worse, this is before ventilation to the outside.
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I know you directed your question elsewhere, but I'll chime in anyway. We don't hold off on using water until ventilation is done, but we DO hold off on ventilation until water is ready. Ventilation that is done too soon and/or in the wrong place prior to a charged hoseline being in place can significantly worsen fire conditions. Using water in any high heat area will NOT worsen fire conditions. It is real nice, but not necessary, to have ventilation ahead of hose stream. Our policy in high rise areas is to leave windows in place. They are often un-openable, difficult to break and glass shards would rain down upon city sidewalks if we did. So extinguishment is often done with NO ventilation of windows. Difficult but not impossible. Proper PPE will do it's job. I know most of us don't regularly fight high rise fires. I just use it as an example of fire extinguishment w/o ventilation.
Don't worry about disrupting the thermal layer. It's presence really only means that there is higher heat at higher levels. Protecting the layer means protecting the heat! Who wants that? Water generally cools all of the levels. Application of water is the main reason we are there in the first place.
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Permalink Reply by Norm Tindell on
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An early indicator of impending flashover is thick, brown, boiling, velvet-looking smoke. As soon as you see that you want to be outside the structure - not inside. Find Dave Dodson's "Art of Reading Smoke" videos on You Tube and you'll see some very good info on fire behavior.
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Is there any difference for the indicators of either a flashover compared to a back draft if you are in the structure? I know what signs to look for while outside a structure but not if already inside attacking.
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Permalink Reply by John Crabbe on
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Both are very bad, however, if you are inside, you have a better chance of noticing indicators for a flashover than a backdraft. Visibility inside a structure will typically be poor to really see anything, which means much of what will be an indicator is what you feel. If it is getting hot, really hot, best to think about either opening up the nozzle or getting out. If opening the nozzle, the "penciling" technique, short quick bursts to the ceiling will help cool the gases and prevent a flashover. For a backdraft, chances are you really won't be seeing much from the inside. Yes check for heat etc before opening doors, etc, use the TIC, etc.
In the end, much of the factors to be concerned about should be indicated before you make a push inside. Read the smoke, get as much info from bystanders or those who exited first. Do 360's, check for other means of entry, think of being creative if need be (such as converting a window to a door), etc. If you find yourself in a lot of smoke and a lot of heat, consider a flashover and take actions to cool the gases
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As I mentioned in an earlier post, a "ventilation induced flashover" is basically the same thing as a backdraft. It is a newer term. The traditional definition of flashover was a fire in the developing stage that reached the point where the entire room lit up. Flames would generally be visible up until flashover point. With backdraft/vent induced flashover the area will have darkened down because available oxygen is used up. No/little flame will be visible. When we open a door or window to enter air is allowed in. It mixes with heat and fuel and lights up violently. The warning is the darkened down fire and the new opening. It is likely the only warning you'll get. So someone on the fire ground has to be able to recognize these conditions. The good news is you will not yet be expected to make these calls.
I suggest you don't get too hung up on the differences between the two when operating interior. High heat is your indicator. Hit it with water immediately or get out immediately.
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John Crabbe,
I have to ask about the "penciling" technique. You describe short bursts at ceiling to cool the fire gases and prevent flashover. Then what? Why not just fully open the line and provide as much cooling as possible as fast as possible?
Also you described turning a window into a door. Are you talking about entering through a window or physically enlarging the opening?
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Permalink Reply by Jim Conrad on
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I have often wondered about that myself. Is there a disadvantage to cooling the compartment too quickly? I would imagine that if I found myself in a room that was about to flash I would be inclined to get as much water on the heat as possible very quickly. If the worry is a victim hiding in the room and you don't want to disturb the layering, what chance does a person who is not wearing ppe have anyhow?
We are being taught to get rid of the heat, not try to manage it.
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