Positive Pressure Attack

[@zaydee07]

For me, this is an outstanding presentation. Thanks for sharing it. From the Philippines.

[@barbnjak1]

The function of the fire service is to "protect life and property". Even an unoccupied house deserves an agressive fire attack. As long as it;s done consistent with safety. Risk vs reward still applies, but that doesn't mean every unoccupied house should be allowed to burn to the ground.

[@barbnjak1]

I don't really like the time factor involved in making openings bigger. By the time you cut and pull the walls, you could already have the fire extinguished. That's assuming an agressive interior attack is made. I've seen way too many videos where fire attack is being delayed so ventilation (horizontal and/or vertical) can be completed. The manpower committment to venting often exceeds that of fire attack. This is pretty much backwards.

[@SFDTNG]

Yes, we used softwood pallets and straw. We used thermo-couple temps along with smoke conditions to determine when we would send crews in. For our drills, the best temperatures to start the evolutions were right at 1400F at the top of the fire room with smoke conditions down to the ground with flames starting to "finger" out from the burn room. After all the PPA evolutions were done, we did let it flash. Flash ooccured at 3m 45s from the time the pallets were burning.

[@markstoks6160]

ladderops @

[@barbnjak1]

When discussing PPA/PPV, we ALWAYS hear about how it must be used properly by well trained firefighters. It is rare that someone spells out the exact time/place/method in which to use it in a real world fireground situation. Training is no good if it's not realistic and I suspect it is often not realistic. The exhaust openings shown in this video are a little (maybe a lot) too liberally sized for my taste and attack was started earlier in stage of fire than we can expect to be operating.

[@richardkeilig4062]

Well done.

[@barbnjak1]

My concern is that modern day fires produce very large amounts of incompletely burned fuel (smoke/fire gases). If the exhaust opening is too small (which in my opinion it will often be), I believe the positive pressure will not be enough to exhaust all of the heat energy and unburned fuel to the exterior. Now what happens? How could it not spread to areas (rooms) of lower pressure or out the attack opening? And light up in the process? What now happens to "standing up" search and attack teams?

[@BP-kn9dl]

I am a PPA instructor in New Brunswick, Canada. We are about to do our practical training in a Build & Burn structure. Did you use softwood pallets and straw? How long did you wait before attacking the fire? Did you ever allow it to flashover? How long before flashover? Great video, well done!!

[@WylieFireRescue]

Great video.

[@barbnjak1]

Depending on layout of house, location of fie and status of interior doors (open vs closed), there very well could be survivable areas. But time is a huge factor. Aggressive fire attack combined with fast primary search is the best way to address the situation. Ventilation shoul NOT take priority over extinguishment and/or search. It should be done in conjunction with those things in a coordinted way, when it would not cause conditions to worsen.

[@barbnjak1]

Yes, but the smoke you're reading at your barometer point is artificially manipulated by PPV. If PPV is started and then stopped based on what you read at "barometer", a lot of time has been lost (and heat/smoke/gases pushed/pulled to "cleaner" areas?) Fire could very well have been extinguished by this time. In our culture we run into near flashover (or post flashover or ALMOST anything else) conditions with a charged hoseline which we quickly operate at 180 GPM to extinguish fire.

[@barbnjak1]

Just curious. Were any tests done where exhaust opening was one half to one times the size of attack opening? I think this ratio is more realistic for most of us. (Typical bedroom with a 30-32 inch door and one or two 30x40 inch windows) Also, were any tests done well after the fire had flashed and subsequently darkened down? This is a more realistic time frame because most of us don't arrive to a fire right when it flashes (or just before or after). We arrive in a later stage of the fire.

[@barbnjak1]

I am all for an outside survey being done. But that time should not come at expense of hose stretch. Should be simultaneous. What I am against is taking time at expense of hoseline advance to enlarge a window opening. If fire location can't be determined from exterior, then yes we go in to locate it, using ears, eyes, TIC, etc. Venting should NEVER be done as a way to locate fire. Nor should it be done to improve visibility.

[@barbnjak1]

I am not 100% against PPV/PPA. I would say it has a place (especially if done by people like you that clearly understand it). Here's what I am against: 1) Starting PPV and then deciding whether or not it's effective (barometer). This may have negative consequences and definitely wastes valuable time. 2) Letting PPV delay in any way the agressive interior attack needed to quickly control structural fires. 3) The idea that inside team deserves clear visibility. Too many proponents cite this reason

[@timking8959]

Why did you use pallets/straw and not modern furnishings? Wouldn't modern furnishings give you more realistic temperatures due to the increased BTU release rates?

[@randyfrassetto2760]

It would have been nice, but for safety reasons, NFPA 1403 doesnt allow use of those types of materials when conducting live fire training.

[@barbnjak1]

I don't like the idea of using the entry as a "barometer". It's a fancy way of saying "we're guessing". Trial and error is not the best way to operate on the fireground. (Yes, it is sometimes the only option.) But by the time you get your "barometer" results, the fire could have been extinguished by an agressive attack.

[@SFDTNG]

I have a lot more info I can email you. We did a lot of tests on steam conversion, flashover temperatures, etc. Feel free to email me your email address at Randy.Frassetto @ LadderOps . com