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Thread: The Battle Can

  1. #21
    MembersZone Subscriber Golzy12's Avatar
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    Quote Originally Posted by captnjak View Post
    Yes, but an unvented room would mean WAY more heat energy present. Can would quickly be overwhelmed. I was referring to actual real world fire conditions.

    IMO, steam is more a byproduct of extinguishment than it is a method of extinguishment. Don't really know the science involved on that one.
    I'm going to have to respectfully disagree with you on this one. A ventilated fire will typically have a higher heat release rate (HRR) than a similar fire at the same stage that is unvented. A single fully involved room is almost always going to be ventilation limited. Any ventilation opening made to this fire without adequate water application will eventually see an increased HRR.

    I think steam will help in extinguishing the fire, that is the whole theory behind Layman's Indirect attack. Use a wide fog pattern in an enclosed area with high heat, the water turns to steam and you let it soak for a few minutes. If you vent the area too soon, the steam will vent and won't have the desired effect. Granted, we aren't creating a ton of steam with 2.5 gallons of water, but if that's all the water I've got I would want to use it as efficiently as possible. If for some reason I wanted to try to knock down a fully involved room with the can, I would call for ventilation to be withheld, discharge the can at the seat of the fire and then get the door closed to let the steam soak.

    A more realistic and practical scenario would be to use the can to hit any fire rolling out of the fully involved room and pull the door closed. Let the door confine the fire for you and save the limited amount of water you have. Call for a line and let them put the fire out. If the line is delayed, the left over water in the can can be used to slow any fire spread through the closed door. If you dumped your entire 2.5 gallons on the fire, pulled the door closed, didn't get the fire totally out and realized the line was delayed then you may be in trouble. If the fire redevelops in the room and starts to burn through the door you have nothing to stop it. When water is limited you have to use it effectively.


  2. #22
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    Quote Originally Posted by Golzy12 View Post
    I'm going to have to respectfully disagree with you on this one. A ventilated fire will typically have a higher heat release rate (HRR) than a similar fire at the same stage that is unvented. A single fully involved room is almost always going to be ventilation limited. Any ventilation opening made to this fire without adequate water application will eventually see an increased HRR.

    I think steam will help in extinguishing the fire, that is the whole theory behind Layman's Indirect attack. Use a wide fog pattern in an enclosed area with high heat, the water turns to steam and you let it soak for a few minutes. If you vent the area too soon, the steam will vent and won't have the desired effect. Granted, we aren't creating a ton of steam with 2.5 gallons of water, but if that's all the water I've got I would want to use it as efficiently as possible. If for some reason I wanted to try to knock down a fully involved room with the can, I would call for ventilation to be withheld, discharge the can at the seat of the fire and then get the door closed to let the steam soak.

    A more realistic and practical scenario would be to use the can to hit any fire rolling out of the fully involved room and pull the door closed. Let the door confine the fire for you and save the limited amount of water you have. Call for a line and let them put the fire out. If the line is delayed, the left over water in the can can be used to slow any fire spread through the closed door. If you dumped your entire 2.5 gallons on the fire, pulled the door closed, didn't get the fire totally out and realized the line was delayed then you may be in trouble. If the fire redevelops in the room and starts to burn through the door you have nothing to stop it. When water is limited you have to use it effectively.
    Sure the ventilated fire will have a higher heat release rate. But most of that heat will be going out the window. Whereas the unvented fire will have a great deal of accumulated heat energy.

    You mention trying to knock down a fully involved room with the can by hitting the seat of the fire. What seat? The room's fully involved. There is no seat. Or should I say the whole room is the seat. You've lost me entirely with this one.

    I don't understand the idea of the steam "soaking". I've not heard of Layman or his theory but I suspect I know why it's just a theory. When water hits fire it absorbs energy, some of which is used up turning the water into steam. Energy is transferred from the fire to the water. The steam may provide a certain amount of smothering ability but this is not how water extinguishes fire. Either we use enough water to stop the chain reaction that is fire or we don't. If we don't it's not going to be extinguished no matter how long the steam "soaks".

    I've gotta say though that your final paragraph is pretty much perfect.

  3. #23
    MembersZone Subscriber Golzy12's Avatar
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    Quote Originally Posted by captnjak View Post
    Sure the ventilated fire will have a higher heat release rate. But most of that heat will be going out the window. Whereas the unvented fire will have a great deal of accumulated heat energy.

    You mention trying to knock down a fully involved room with the can by hitting the seat of the fire. What seat? The room's fully involved. There is no seat. Or should I say the whole room is the seat. You've lost me entirely with this one.

    I don't understand the idea of the steam "soaking". I've not heard of Layman or his theory but I suspect I know why it's just a theory. When water hits fire it absorbs energy, some of which is used up turning the water into steam. Energy is transferred from the fire to the water. The steam may provide a certain amount of smothering ability but this is not how water extinguishes fire. Either we use enough water to stop the chain reaction that is fire or we don't. If we don't it's not going to be extinguished no matter how long the steam "soaks".

    I've gotta say though that your final paragraph is pretty much perfect.
    At least we are on the same page for my last paragraph!

    Maybe saying I would hit it at the seat was bad wording. I would aim for the lower part of the room, concentrating less on attacking the burning gasses and more on the solids. Either way it sounds like we can both agree it isn't an ideal attack method.

    Lloyd Layman is the "Father of Fog" he is the guy behind RECEO-VS and the indirect method of attack (not a theory). The wrote the books Attacking and Extinguishing Interior Fires and Fire Fighting Tactics both still cited regularly. More about him here http://onlyminutesaway.com/wp/history/lloyd-layman/

    Norman's Fire Officers Handbook goes into pretty good detail about the indirect method of attack.

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    Interesting guy. Thanks for the link.

    I have to admit that I don't know much factual information about fog for structural firefighting. No one, past or present, in my department has ever seemed to have had any use for it.

    But that alone probably says a lot.

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