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PPV Challenge

It is my belief that properly implemented PPA used for fire attack is the safest, quickest, most effective way to provide initial ventilation for single-family residential buildings. I base this on my study of the subject and my experience as a ladder company firefighter, lieutenant, and captain. I hear many people talking about PPA and how it can, or cannot be used, it’s effectiveness, and safety. I, personally, have never experienced a negative outcome with properly implemented PPA. I have never seen a video or read a case study of a negative outcome with properly implemented PPA. I often hear second-hand accounts or examples of potential negative outcomes but have yet to see the evidence of a documented poor outcome or a negative impact of properly implemented PPA from empirical research or an incident scene.

I do not think going to the roof is inherently dangerous nor would I shy away from assigning crews to vertical ventilation when appropriate. I am not looking for a vertical, horizontal, versus PPA discussion. What I am looking for is EVIDENCE to support claims of ineffective or unsafe PPA when done PROPERLY.

Please do not submit video links of situations where improper PPA is used. I’ve seen those. So has everyone else. I am talking about well-trained firefighters using the tactic properly.

For the purposes of this question “Properly Implemented” will be defined as my understanding of the procedures and contra-indications outlined by Kris Garcia and Reinhard Kauffman in their book “Positive Pressure Attack for Ventilation and Firefighting”, Fire Engineering Books/Pennwell , 2006

“Properly Implemented”

1. Appropriate size exit point established in acceptable location (in or near the fire room)
2. No victim(s) in the exit point
3. Fan at hose team entry door
4. Hose team ready
5. Blower turned into door before firefighter entry
6. Backdraft conditions NOT present

The CHALLENGE:

Can you provide a verifiable example of a fire where a “Properly Implemented” PPA attack was used and there was a negative outcome?

Tags: attack, positive, pressure, ventilation

Views: 418

Replies to This Discussion

Chief,
Thanks for the post. Very informative.


Phil Jose said:
Mike,

The point of using the NIST video and wind driven fires was more as an example of the weather conditions that we commonly experience in Seattle. A 5 MPH wind could have an affect on Fire Behavior. Outside of the tactics on a highrise event, Houston recently had a LODD where the wind may have contributed to the fire spread in a residential structure, and ultimately the loss of life ( I am guessing that severe winds is also a contra indicator of using PPA?). It has also occurred in other parts of the US. My attempt was to bring up another case, in which the fire is contained (the box isn't broken) and when the box is broken (either by fire or firemen) then it has a profound effect on the fire behavior inside the structure. While I recognize that a fan can and will overcome such a small force of wind from the outside, during the time in which the window is broken and the fan is turned in the fire behavior can change.



Mike Walker said:
Hey Kris

In an attempt to speak to your questions I think it is important to remember, that PPV in a High-Rise situation is somewhat different then other applications. The window should not be intentionally taken out in a High-rise until wind direction is known but if the window fails and a wind driven fire condition results, then PPV can be used to help alleviate some of the effect.

As to your other question about the 5mph wind. I try to emphasize to my students that PPV is an augmentation to horizontal ventilation. I realize this my stand in the face of strong proponents of PPV but I strongly believe that my statement is accurate. Once the window is gone, either by the fire causing it to fail or by a firefighter, the smoke movement should be observed. If it reacts the way you want it to, then the process can be sped up by using the fan, if the conditions aren't what you're looking for, then more attention needs to be placed on what happens if/when the fan is utilized. The blower can easily overcome up to a moderate wind but to do so the fan placement has to be perfect or damn close to it. The path must be closely monitored in order to maximize the slight pressure increase from PP. The size of the exit opening(s) need to be watched as well. Every window interior firefighters open inside the structure causes a reduction in pressure, thus reducing the blowers effect.

This, to me, is where the rub exists. PPV requires personnel to actively maintain, evaluate, monitor, correct conditions throughout the operation. Most crews are accustomed to performing ventilation and then moving on to other tasks once they have achieved the desired result.
Without trying to hijack my own thread.

Wondering if you guys would be comfortable taking the high-rise stuff directly to compartmentalized multi-family residentials. I'm thinking 3 or 4 story apartments with enclosed stairwells and center hallways. I don't see any real difference in the layout relative to the impact of PPV within such a building as compared to a 10 story. The study shows no negative impact from pressurizing the stairwells. Never. Unless I missed something (which is possible)
Phil,

I've had very good experiences with PPV in the types of buildings you mentioned in your last post. If the crews will place the blower at the base of the stairs and/or entrance to the building and not try to carry it to the affected floor, it does a great job. With that being said, crews have to be cognizent of wind conditions. Now remember, I'm speaking from Oklahoma experience where we routinely experience very high, gusty winds.

Here is another thing we've done that worked well when we've experienced a fire apartment on the windward side of the building. The fire was extinguished but still smoky. We started up the fans and intentionally kept the exit opening small. This allowed an of increase of pressure within the building to the point we were able to overcome the wind. I hope this doesn't mess up anyone's theories but I know it works. But remember, the fire was extinguished before we did this, meaning the smaller exit opening. Also, the option to cross ventilate through the hallway wasn't an option because of the location of the fire.
Oh on a related matter,

We've recently purchased electric blowers. They work fantastic during the salvage and overhaul phase. Good clean air coming into the building. Let me use a fire we made yesterday as an example. Crews had vented the roof due to the attic involvement on a two story (which by the way, they accomplished very fast), they started the gas blowers to augment. The fire was extinguished. After the building cleared of visible smoke, we used a CO monitor to check the levels. They were around 130-140 ppm of CO. We turned off the gasoline blowers, tuned on the eletric blowers, in less then one minute, the CO levels dropped to 10 ppm and reached 0 ppm in less then 5 minutes. True story. We were taking readings upstairs and downstairs.

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