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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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doesn't hor venting just give the fire an easy source of oxygen, isn't that the same as opening the front door and then BOOM
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Permalink Reply by John Crabbe on
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I think you are thinking of a backdraft with an oxygen derived, smoldering stage fire with the "BOOM". Not really the case.
With horizontal venting, sure you can introduce oxygen, but more importantly you are giving the heat and pressure and easy place to go....outside, not in. Now if not coordinated properly, horizontal venting CAN spread and intensify the fire, hence it should be done when you have hose teams ready to hit the fire (IE charged lines, crew masked up, PPE on, etc). This is also a reason that law enforcement should be told not to just arbitrarily bust out windows etc, believing they are "doing you a favor", or doing so "searching" for victims.
Whereas, if coordinating such vent with a fire attack, it can be a very good tactic. When you have the window out and a line in, the heat and smoke will naturally go from the high pressure (inside and now being affected with water) to the low pressure (outside) as opposed to not having vent and taking the beating.
Another tactic (not mentioned here) is Positive Pressure Attack (PPA), where a power fan is placed by the entry, windows busted out in the fire rooms, fan turned into the entry and you let the fan work about a minute before making entry. Essentially this creates a higher pressure from the entryway while the busted window creates the low pressure source for the fire to vent to. If doing such a tactic, fire will appear to "blowtorch" out the window. This can also help cool the inside of the structure and improve visibility prior to crews making an entry. This is another option out there and does have its place, has its pros and cons, but there will be those adamently against it and those for it. Personally, I see it as another option available.
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Permalink Reply by Jason Van Order on
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As stated venting the roof WILL increase fire intensity if that is all you do. If you dont pair it with some sort of water attack the vent hole will allow hot gasses and smoke to exit and draw in fresh cool air. All you did is turn a vent controlled fire into a fuel controlled fire. Unless you have a charged hoseline ready to go when you cut your vent it can get bad quick. As for sounding the floor we were taught to sound it as you move along. More important with the cheap modern building materials being used. I would rather take the little bit of extra time to make sure my chunky butt isnt going to be taking a dive when the floor gives way.
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Permalink Reply by captnjak on
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I don't advocate using the line on "cold" smoke, for lack of a better term. My point is that it is not necessary, and can often be unsafe and counterproductive, to hold off on opening the line until you "make" the original fire room. When we are met with high heat, we should open the line regardless of our position in relation to original seat of fire. I no longer even like the term "seat of the fire". Due to modern fire dynamics, most of the time we arrive at fires that are in a ventilation controlled state. Fire has darkened down and there is an accumulation of heat and fire gases throughout the area. The "seat" of the fire can be all around us. Any introduction of air via openings, including the one we enter through, has the potential to cause a drastic re-ignition and rapid fire growth. Any time we are met with high heat upon entering we should start operating. I don't believe in "holding it in check". We have high heat. We have water. We use water. The notion that we are going to go in under the heat and smoke layer, find the burning material and extinguish it is a tactic for a fire that is still developing. If we are lucky enough to arrive at this stage, then we should do just that. But I doubt most of us can get there and be ready with water that quickly.
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Permalink Reply by 55 TRUCK on
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Again I have left out critical points to my response. Yes we do not want to spray water in a smoke filled room with little to no heat. We don't spray it willie nillie.
Hope this clears up any confusion. I will post more later. I have a 4yr old using me as a jungle gym at the moment.
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We were shown positive pressure venting and it did work pretty cool, we were in the structure with a live burn when they vented hor with ppv isn't that a bad thing if you have guys in the structure ahead of and attacking fire. Would that not be drawing the fire towards them trying to get at the fresh air?
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Permalink Reply by Norm Tindell on
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It pushes the heat away from the crew when done correctly.
Positive pressure ventilation is even more time-sensitive than vertical ventilation, though. It is a tactic that must be understood well by all and practiced regularly. We've looked at it, but have yet to try it. Used unwisely, it has caused a few close calls.
A nearby department swears by it. They set a fan at the door and turn it away 90 degrees. An opening is created at the opposite end of the building, usually a window. As soon as the hose team finds the seat of the fire the fan is turned towards the door. Never use this tactic unless you: 1. coordinate with everyone; 2. practice, practice, practice...and; 3. always make sure the firefighters on the line are between the fan and the seat of the fire. It dramatically improves visibility and accelerates horizontal ventilation.
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Seems like every guy who describes PPA (which I believe is what you are refferring to) does so differently. This includes the "professionals" who take money to teach it. That alone is a good reason to be skeptical about it. And how do you practice if you can't replcate real life conditions because you are restricted to burning wood?
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Permalink Reply by Don Catenacci on
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Captnjak,
I have used PPV and PPA and the truth is like anything else we do there is a time and a place for it and knowing when it is right is every bit as important as deploying it properly. It is no more the answer to every venting situation than a vertical vent is. If improperly applied it has the potential to increase the fire dramatically.
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We now have trucks designated as ventilation units. They carry fans. For us they are mostly used to pressurize stairways in high rise buildings. They are assigned to all high rise fires automatically. Could conceivably be used during fire attack but I'm not aware of that having been done. Mostly used for post control smoke movement to clear halls and stairs or in large warehouse type occupancies.
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I believe our chief shares your skepticism. That may be the leading reason we're not doing it, or even learning about it in an organized fashion. There have been many failures, some documented in places such as YouTube. It's risky.
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