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Positive Pressure... neighbours' house?

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  • #16
    Very true, however the Drill Tower is all we have without burning down an occupied building or multi-family dwelling. LOL. I posted that and will try it to get the "basic fundamentals" of the theory. Since I came-up with that idea I have it figured-out in my head how we can set the Tower up to try this; when I get back to work I will visit the Tower and see if "reality" agrees with what I have in my "ole pea brain."

    Thanks for the increase in the challenge though... I'll post if I am able to make it work.
    "Be LOUD, Be PROUD..... It just might save your can someday when goin' through an intersection!!!!!"

    Life on the Truck (Quint) is good.....

    Eat til you're sleepy..... Sleep til you're hungry..... And repeat.....

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    • #17
      Good tactic in theory.

      May be valuable in our few strips malls if we ever get an incident there.
      Train to fight the fires you fight.

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      • #18
        I have heard of this tactic before but never tried it. I seem to remember it in the positive presure attack book from the guys from salt lake. (i cant remember their names)

        Increasing the pressure in the attached exposure would prevent the smoke and heat from traveling to that area. In my mind the air in the exposure occupancy (higher pressure) would flow to the air in the fire occupancy (lower pressure). In theory this would prevent the smoke/heat travel into that area so voids would not be an problem the air is traveling to the fire area. this sounds very simialar to PPV in stairwells in highrise buildings a commonly used tactic. I am thinking it is used to lessen smoke travel versues flame spread.

        I would think that a failure of a window in the exposure area could cause a problem if not address. By creating a draft, and drawing the fire to the exposure. However shutting a door or just cutting the fan off would solve that issue.

        RFDACM02- I am confused on the comment about cramming the exposure occupancy with clean air. What problem would that cause. the only way that would increase a fire is if the oxygen level in the air some how increased above 21%. With no exit for the air; the air is not going to "flow". if the fire does penitrate the fire wall and get into the exposure, it is no longer and exposure. Just cut the fan off and put the fire out. Either way you always need a crew inside the exposure to monitor the conditions and fire spread.

        I am thinking this is along the same lines as the newer air track management theories that are invading out shores from europe. I have learned alittle about it, understand the concepts. However question the real world application of it.

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        • #19
          Originally posted by RFD21C View Post

          RFDACM02- I am confused on the comment about cramming the exposure occupancy with clean air. What problem would that cause. the only way that would increase a fire is if the oxygen level in the air some how increased above 21%. With no exit for the air; the air is not going to "flow". if the fire does penitrate the fire wall and get into the exposure, it is no longer and exposure. Just cut the fan off and put the fire out. Either way you always need a crew inside the exposure to monitor the conditions and fire spread.
          My skepticism is more with the sudden failure of a window in that exposure or with a failure of the separation. When an unintended opening occurs, it must be noticed and reacted to, for someone shut off the fan. Any delay in this I'd fear might increase fire intensity. I'm not convinced the pressurized air addresses the most common routes of exposure. I think successes of this tactic may not be able to be validated, as they may have been actual success of proper separation in the first place. I guess there's value on preventing smoke spread though, so in that there's some validity.

          As I said, I'm a skeptic of PPV in many cases, and this seems like a an extrapolation of a only somewhat proven tactic. I know it works when it works, but so do water curtains. Both fail miserably, when they fail too.

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          • #20
            Originally posted by RFDACM02 View Post
            As I said, I'm a skeptic of PPV in many cases, and this seems like a an extrapolation of a only somewhat proven tactic. I know it works when it works, but so do water curtains. Both fail miserably, when they fail too.
            I couldnt agree more, I have the scares to prove it. from the use of positive pressure in an ordinary construction cape cod. Like I said above i dont think this tactic is put the fan at the door to the exposure and walk away. my view it is used in conjuntion with a engine and truck crew in the building to check for extension and monitor the fire wall. popping inspection holes and pulling ceiling is still needed. Hose line at the ready. My thought is it would be useful in preventing the smoke spread to the exposure to reduce the damage. even if a window fails and goes unnoticed if the exposure crews are babysitting the fire wall like they are suppose to they can hit the fire when it start to breach it and is still managable.

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            • #21
              Originally posted by RFDACM02 View Post
              As I said, I'm a skeptic of PPV in many cases, and this seems like a an extrapolation of a only somewhat proven tactic. I know it works when it works, but so do water curtains. Both fail miserably, when they fail too.
              FWIW, PPV used properly is a very effective tactic. The problem is, I've seen a lot of totally botched attempts at PPV. "Water curtains," OTOH, don't work at all.
              Last edited by DeputyMarshal; 12-27-2010, 10:48 PM. Reason: typo
              "Nemo Plus Voluptatis Quam Nos Habant"
              sigpic
              The Code is more what you'd call "guidelines" than actual rules.

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              • #22
                Originally posted by FireFuss
                That building is standing today because of 40 or so sprinkler heads outside on the adjoining wall. They were pressurized by an engine, and acted as a sort of wall mounted water curtain.
                Direct cooling by wetting an exposure works just fine; a traditional "water curtain" between the fire and the exposure does not.
                "Nemo Plus Voluptatis Quam Nos Habant"
                sigpic
                The Code is more what you'd call "guidelines" than actual rules.

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                • #23
                  Our water curtain appliance is designed to tilt so it can flow across the surface.
                  ?

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                  • #24
                    And back to the original question - it worked well in our situation , the only thing I would have done differently ,would to be have someone stationed at the fan to kill it if there was a wind shift or an inversion of some sort. This was an extermely smokey fire and took a long time to self vent. (multiple roofs /ceilings ) we also had gone completely defensive when we initated the ppv on the exposure and had two lines and a portion of the drop ceiling down to monitor the entire wall. (no vents in the flat roof)The fan was in the C/D corner of the exposure building (one story)and the vent was the front door on the A side of the exposure.
                    ?

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                    • #25
                      I think a lot of FF's lose track of two things about PPV. One: It's a TOOL. Two: That TOOL should have an OPERATOR with it and it DOES have a THROTTLE which DOES NOT necessarily have to be set at full throttle. I LIKE PPV's, have used them on various building constructions. Used with DISCRETION they can speed up your work and make your life EASIER, Used IMPROPERLY: Hello PARKINGLOT! T.C.

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                      • #26
                        Originally posted by Rescue101 View Post
                        I LIKE PPV's
                        Minor nit-pick: PPV is a tactic, not a tool. This tactic is usually implemented using a fan (tool) -- either gasoline powered or electric -- but can occasionally even be accomplished by taking advantage of a convenient wind.

                        I do agree with your overall assessment.
                        "Nemo Plus Voluptatis Quam Nos Habant"
                        sigpic
                        The Code is more what you'd call "guidelines" than actual rules.

                        Comment


                        • #27
                          Originally posted by DeputyMarshal View Post
                          Minor nit-pick: PPV is a tactic, not a tool. This tactic is usually implemented using a fan (tool) -- either gasoline powered or electric -- but can occasionally even be accomplished by taking advantage of a convenient wind.

                          I do agree with your overall assessment.
                          I agree with your assessment. For the purposes of the THREAD however,I DON'T think the OP was thinking Mother Nature PPV. T.C.

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                          • #28
                            Pressurizing an exposure is VERY effective.

                            I have used it and had success on the following exposures; strip malls, a dwelling w/ attached garage and adjacent high rise floors.

                            The higher the interior pressure, the more effective it will keep fire out!
                            Cognition before Ignition

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                            • #29
                              Originally posted by J.Beck View Post
                              Pressurizing an exposure is VERY effective.
                              You might want to reread the initial post. The OP appears to be talking about detached exposures.
                              "Nemo Plus Voluptatis Quam Nos Habant"
                              sigpic
                              The Code is more what you'd call "guidelines" than actual rules.

                              Comment


                              • #30
                                Originally posted by DeputyMarshal View Post
                                You might want to reread the initial post. The OP appears to be talking about detached exposures.
                                I probably did misunderstand the OP, although, the point remains the same - pressurizing an exposure, attached or not, is VERY effective.
                                Cognition before Ignition

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