Thread: Flash Over

  1. #26
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    Sorry, I might have just been unclear. When I say shooting into the "really hot stuff" up in the ceiling in a hostile environment, and more water getting through the layers... I meant in comparisson to a fog or even straight stream going up through this same heat exposure. Then, as you said, more water "survives" the journey through to break apart on the ceiling into the larger droplets as opposed to converting to steam earlier on.
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    Interesting, have you guys used High Pressure or Ultra High Pressure lately?

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    It was mentionned earlier but I don't think anyone here (in NA) has used it- not in this thread anyways.

    We've talked a lot about it- in our area it would be nice to incorperate the lower volume philosophy... That would turn even our 75' "telesquint" with a 500 gallon tank into a tanker.

    I can't see it happening, but the theory is promissing in our rural area where water is always an issue.
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    Quote Originally Posted by Rescue101 View Post
    See if this helps: To my knowledge there have been NO survivors involved in a true flashover.
    Not so.

    Two firefighters in Clearwater, FL survived a flashover in the hallway of a hi-rise about 6 years ago. Do an on-line search for the "Dolphin Cove" fire. Its on one of the government sites, FEMA's I think...

    Ive also heard of others, but since they didn't involve fatalities, Ive yet to find an on-line report to review.
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    Dave,I stand corrected. I would STILL rather avoid being in one at pretty near any cost.The survivability percentage is hovering at the real low end of the scale.New building construction certainly doesn't help. T.C.

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    Quote Originally Posted by Eno821302 View Post
    Sorry, I might have just been unclear. When I say shooting into the "really hot stuff" up in the ceiling in a hostile environment, and more water getting through the layers... I meant in comparisson to a fog or even straight stream going up through this same heat exposure. Then, as you said, more water "survives" the journey through to break apart on the ceiling into the larger droplets as opposed to converting to steam earlier on.

    I just attended an extreme fire behavior lecture by a Battalion Chief, and my understanding is that cooling the layers without return (we use combo nozzles around here) is more preferred than bouncing it off the ceiling, where the expanding steam will push the hot layers down onto you. A properly applied fog with no return in fact contracts the gas layer because the cooling gases contract more than the expanding of the steam.

    Does this concept not apply with smooth bore nozzles (with regards to controlling the ceiling environment)?

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    Quote Originally Posted by GaiusPaul View Post
    A properly applied fog with no return in fact contracts the gas layer because the cooling gases contract more than the expanding of the steam.

    I have to say "no way" on this one.

    Water expands 1700 times when it is converted to steam. Cooling gasses at the ceiling cannot possibly cause these gasses to contract at a higher ratio than the conversion of water to steam...Simple physics.

    If there is no return from the hose stream, it is simply because it was a very short burst and the water converted before it had time to fall back to the floor level, not because the gasses it cooled were reduced in volume by a factor greater then 1700X.
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    Quote Originally Posted by Rescue101 View Post
    Dave,I stand corrected. I would STILL rather avoid being in one at pretty near any cost.The survivability percentage is hovering at the real low end of the scale.New building construction certainly doesn't help. T.C.
    Not trying to bring you down in any way. These guys in Germany however made it out alive from a new building, a discount food store with large open layout: http://www.youtube.com/watch?v=Io15LR6XTJI

    The text is in german, but it informs that the initial response was for a trashcontainer on fire which explains the insufficient ammount of GPM put on.

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    The point being made here isn't that that larger volume of water wouldn't convert into more steam- the point being made here is that that larger volume of water broken apart in larger, coarser droplets will absorb much, much more heat before making the conversion. Smaller volume and fine particles will convert to steam almost instantaneously upon entering the atmosphere. With some high pressure, low volume tactics this is to your benefit...

    I do notice that with both high pressure rigs, use of the equipment seems to happen from behind shelter, through a door even in one case- from outside in another. If you're in the room with an angry dragon, I'd rather be waving a sword around than shooting a bb gun. But then again, that's why we use volume tactics...
    Last edited by Eno821302; 09-17-2008 at 11:56 AM.
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    Quote Originally Posted by Eno821302 View Post
    Sorry, I might have just been unclear. When I say shooting into the "really hot stuff" up in the ceiling in a hostile environment, and more water getting through the layers... I meant in comparisson to a fog or even straight stream going up through this same heat exposure. Then, as you said, more water "survives" the journey through to break apart on the ceiling into the larger droplets as opposed to converting to steam earlier on.
    OK, we're definitely on the same page here.

    Quote Originally Posted by Eno821302 View Post
    If you're in the room with an angry dragon, I'd rather be waving a sword around than shooting a bb gun. But then again, that's why we use volume tactics...
    And here too...

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    I enjoy paying attention (Size up) to what the smoke says outside... inside... smoke push. I put my flashlight near my mask lens and check the smoke push.

    Paying attention make a huge difference if you back out or go aggressive.
    Last edited by CooterRob; 09-18-2008 at 09:38 PM.
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    Thumbs up Cfbt

    In our state in Australia we are all trained in what we call "Compartment Fire Behaviour Training". I've done both level 1 and 2.

    What we are taught in a nutshell is to have our Akron branches set to 115lpm and a fog cone of approx 60 degrees. We have short and long bursts with a short burst being a quick on/off and a long being on for a second or 3 then back off, the cone of water is aimed at the ceiling and the pump operator has the pump running so that there is 700kpa of pressure at the branch. We are taught how to enter a building that hasn't flashed yet so that we can cool the hot fire gases that are near the ceiling thereby pushing the fire back onto itself.

    It works quite well and our Akron branches are the 1720 type with adjustable flow rates and spray types, we use 38mm (1.5in?) diameter hose for our fire attack.

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    Quote Originally Posted by Eno821302 View Post
    Pretty impressive stuff- both of those. I'm particularly intrigued on the cold cutter / extinguisher! That rosey number is pretty neat as well.

    Are those products finding their way to use in North America at all?
    Better late than never, but I now found out Penn Township Fire Department, USA has a Cobra CCS. And they have published a report of a successful operation with it on the company website.

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    Look guys,I work in a flashover trailer.I'm Still(and going to)teaching my students to avoid flashovers.That means recognizing precursors and taking actions to avoid the situation.Thanks to all who brought to my attention that there HAVE been survivors,great news but I'm still not going to try it to find out. NO GOOD can come of a flashover and that is the FACT. T.C.

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    Talking French politics?

    First of all, forgive my poor english (classrooms are too far ^^)

    In France, studies on flashover and backdraft came really late...
    I've read part of previous posts, and many things are really.

    Nowadays, we buy furnitures with plastic foam, and our parents bought furnitures in oak as we bought the same made in some species of conifers.
    All that leads too more smoke. A gift for us: more fire, more violents. With this change, another thing appears: the differents oil shocks, the increase of living cost, and many other things make people looking for diminuing thermal leaks from their houses. By the way, it decreases air exchange beetween inside and outside, helping flashovers/backdraft to occurs.

    The result of french studies, travelling around the world (northern europe and america too), is to protect FF as we can: we need to work, limitating as it is possible, the extension of fire, but we need to work in security.

    We work by pairs of FF, and we can't break them.
    In our pumper, we've two or three pairs, depending on the departement (and the type of pumper of course).
    For habitation fire, we'll have at least two pumpers, and some departement will add other vehicles (ladder, bataillon chief, EMS...). It depends on the type of habitation, informations get on the call... So it makes at least 4 pairs, with two pumps.
    Each pairs can (in theory) only use one fire nozzle. Debits for room(s) fire will be on 500 liters/min (about 132 GPM).
    In the room, the nozzle is used only by instant opening/closing.
    At the door, a first test is done on the ceiling: if water drops, the smoke is not too hot, and we can progress in the room. A new test is done a few meters forward.

    If water becomes steam, the smoke needs to be cooled. This is done by drawing figures on the ceiling (mostly characters in fact: "O", "Z" or "T").
    A new test is done after that.

    The choice is to engage the strict minimum of personnels. The second pair is outside, ready to be engaged to save the first.


    This way of working leads to less than one pair trapped in flashover per year nationwide.

    Anyway, our nozzles can give their debits on a sort of water screen. If a pair is trapped, seing angels dancing too far from the exit, they have to lay down on the ground, the nozzle beetween them, and facing the ceiling. The screen and all the stuff, (suits, boots, helmet) will do the rest. Since the application of these rulls, we had some FF trapped in flashover, and they're still alive... (As their suits not ^^)

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