1. #26
    makes good girls go bad
    BLSboy's Avatar
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    Sep 2001
    On the beach, Fla/OCNJ


    Quote Originally Posted by PaulGRIMWOOD View Post
    BLSboy - Yes your text book analysis of Flashover and Backdraft phenomena is exactly that .... 'text book' But in reality there are many more aspects from a practical point of view.
    • Flashover is mainly heat-induced
    • Backdraft is mainly air (oxygen) induced
    • Flashover may also be induced by air being fed into the fire area
    • Pencilling a straight stream is one way (but not the best way) of tackling flashover conditions
    • Effectively pulsing water-fog will not upset the thermal layer
    • In such a large open plan area with even an average fire load, a well involved developing fire is not likely to be controlled by hand-lines alone
    • Backdraft conditions in small compartments or buildings may also be tackled using indirect water-fog from the exterior
    • Any openings on the C side as you discuss might be difficult to create and not offer us too much more in way of a tactical advantage
    Paul, now that you mention it, IIRC, I recall a story of 2 Brothers out in Co, I think, that died in a SFD, after the fire was pretty much under control. Someone popped a window where they shouldnt have, fire got a nice deep breath, and flashed.

    But, from your Point of view, which would be the best way to tackle ventilation for this scenerio?
    AJ, MICP, FireMedic
    Member, IACOJ.
    This message has been made longer, in part from a grant from the You Are a Freaking Moron Foundation.

  2. #27
    PaulGRIMWOOD's Avatar
    Join Date
    Jul 1999


    BLSboy I think Delta's post on Chief Dunn's lecture from 20 years ago says it all for me and I find myself totally in agreement with this general strategy. However, I would suggest that for much smaller stores the strategy might actually reverse. Under such fire conditions, I would probably prefer to remove the windows (at a high level) prior to entry, allowing a good few seconds for conditions to develop or stabilize, prior to committing firefighters inside.

    Quote Originally Posted by DeltaCreek View Post
    If I remember correctly, 20 years ago Chief Vincent Dunn expressed in a lecture he was giving on rollover and flashover, that venting store front windows should be delayed as long as possible, or not attempted during offensive operations. He suggested considering the location of a fire, in relation to the window openings, in a building with a higher ceiling. The fire itself will be present once it grows, along with the heat and gases, at the ceiling level. Opening store front windows, horizontally venting, allows air in below the fire. If you consider the theoretical model of the pot belly stove it's quite apparent what he meant. He summed it up by saying it is a difficult decision for a fire officer to determine when horizontal ventilation would be more of a detriment than a benefit. I took away from the class that there is a point in a fires growth when horizontal venting allows fresh air in to feed the fire, and the horizontal opening that was created cannot effectively release the resulting growth of the fire.

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