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PPV Tactics
Hey folks. Been a while since I've been here but visit the site quite often. Does your dept. utilize PPV? If so, how often. What conditions in your mind must be met before PPV is used? I've seen some disasters if used incorrectly. But seen some very good results. Seems some departments are still on the fence with the tactic. Your thoughts and insight are appreciated!
Replies to This Discussion
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Permalink Reply by Don Catenacci on
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Neither department I am a member of uses PPV as part of attack. We use it to clear heat and smoke once the fire is knocked down.
The negative aspects of forcing more air into the fire area and increasing the fire, sometimes to the point of flashover, have negated the sometime benefit of moving heat and fire by-products away from attack crews.
NIST/UL studies have shown that if we limit the fresh air being introduced to the fire area we reduce fire growth and chances of flashover. PPV forces fresh air into the fire area and that seems counter to the study's findings.
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Permalink Reply by captnjak on
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I agree with Don. Modern fire environments are very volatile. Any tactic we use must have results that are predictable to a certain degree. I don't believe PPA meets this criteria.
The various people who present themselves as experts in PPA don't even agree on the conditions necessary for success. I've seen the exhaust opening size mandated at anywhere from 1/2 the size of the supply side opening to 3 times the size of that opening. This is a factor of 6. Imagine if we employed that number in our water delivery formulas. That would mean an effective firefighting stream could be anywhere from 40-240 GPM. Teach that in any school and you'll be thrown out.
PPA can't be trained on in real world conditions. Modern fire behavior in buildings does not mimic wood pallet fire behavior in a burn room. The heat and pressure developed is so much higher and happens more rapidly in a typical house fire. This makes PPA training unreliablr to some degree, IMO.
PPA does not provide enough reward to be worth the risk. The upside is that the building is cleared of smoke more quickly. In a perfect scenario, I suppose the fire can be knocked down a little more quickly. The downside could be catastrophic, even with a handline in place.
We do use PPV for smoke control, mostly in high rise buildings (over 75 feet) and large floor area commercial buildings with limited windows.
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I've been thinking on this a little after seeing Don's comments above. Have the NIST/UL studies changed anyone's viewpoint on PPA? The studies indicated strongly that the best ventilation tactics are all about limiting to the greatest extent possible the effects of our venting on the fire environment. PPA looks to do the exact opposite of that. The occasions where PPA would be appropriate, IMO, have just about been eliminated.
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Permalink Reply by Mike Pasqualicchio on
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captnjak...I think you presented a logical response to why PPA has too many variables associated with it to make it work efficiently. Obviously there are those who will oppose, but this creates meaningful discussion. PPA has to be coordinated perfectly 100% of the time. Any deviation from this coordination may lead to a disastrous situation. The percentage of fires where PPA can be applied is small. As we all know, a fire ground is a symphony of chaos, communication will have to be a disciplined tactic for PPA proponents to master. Those factors alone and the amount of near misses we see from improper execution in training makes PPA a tactic that does not fit our needs.
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Permalink Reply by Jeff Rollins on
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We have used PPV on several residential fires and have had good results. Vent the fire area, start PPV, send in attack team (PPA) and knock down the fire. Continue PPV until overhaul is completed. PPV increases visibility, reduces heat, both good for the firemen.
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Jeff Rollins said:We have used PPV on several residential fires and have had good results. Vent the fire area, start PPV, send in attack team (PPA) and knock down the fire. Continue PPV until overhaul is completed. PPV increases visibility, reduces heat, both good for the firemen.
Just curious if the points I've raised are of any concern to you or your department. How do you handle them?
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They won't until the day something bad happens. I know FDs that the fan comes off the rig and is positioned sometimes even before the line is pulled. I am not saying they fire it up then, but it is so ingrained that it has become automatic for them.
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Don Catenacci said:They won't until the day something bad happens. I know FDs that the fan comes off the rig and is positioned sometimes even before the line is pulled. I am not saying they fire it up then, but it is so ingrained that it has become automatic for them.
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I am not spoiling for a fight. I am not looking to denounce anyone. It may appear to be the case but guys will have to trust that I'm coming from a good place. That place being firefighter safety.
I'm afraid you're right that it will take something horrible happening to get the attention of some guys. I hope like hell I'm wrong about this stuff. But I fear I'm right. Success up until now may be based purely on luck. When it comes to PPA, it seems to me there are just too many things that need to be known that are not readily knowable to any trustworthy degree.
I have never used PPA. I've never even attended a training session on it. I have read extensively on it. I've visited all the websites on it. The more I saw, the more wary I became.
Again, I hope I'm wrong.
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Permalink Reply by Mike Gemberling on
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I guess this discussion goes as I thought. To me it seems a very dangerous tactic for a dept our size that has never really trained on it. It was taught initially in FF2 but it seemed rather vague as far as how to read and when to use it. It would also seem ppa is a norm for some. I really do appreciate everyone's comments as I constantly want to learn and grow in this field. Well, I'm 46 but I think the old brain still has a few tricks left. Keep this discussion open please!
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Mike Gemberling said:I guess this discussion goes as I thought. To me it seems a very dangerous tactic for a dept our size that has never really trained on it. It was taught initially in FF2 but it seemed rather vague as far as how to read and when to use it. It would also seem ppa is a norm for some. I really do appreciate everyone's comments as I constantly want to learn and grow in this field. Well, I'm 46 but I think the old brain still has a few tricks left. Keep this discussion open please!
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I'm older than you and also still learning. At least I hope I am. The day I stop learning is the day they should throw me out. We either go forward or backward; no standing still.
I'm with you on the "vagueness" aspect. My first big problem is the size of the exhaust opening. No one agrees on the minimum but they all seem to agree that the bigger it is the better it is. Fine, but it's out of our control. The size of the window(s) in the fire area are pre-determined. What if they're just too small? Some say they then nee to be enlarged. Fine, but there is a time factor involved. While we're enlarging the opening(s) the fire grows. And grows. The victims wait longer and every second is vital to them. Meanwhile, the hose is still waiting at the entry point for the fan to get the heat out the exhaust point. Why not just use the hoseline to reduce heat immediately? (Personally, there is no way in hell I'm standing fast at the front door with a charged line while some guy tries to cut away the back wall of the house with a chainsaw so a fan can be used to reduce heat levels.) Plus, there is no way to know in advance how big is big enough. Same goes for the fan. How many CFM do we need to eliminate the amount of BTU's present. Who knows? How many BTU's are present? Who knows? What is the exact ratio between heat energy present and the CFM's required to exhaust it out an opening of the size we have created? Who knows? Can increasing the fan's capabilities make up for a smaller opening? Who knows?
I'll answer that. No one knows. And no outside survey is going to tell us. Nor will it tell us the layout of the building or the status of interior doors.
They tell us departments should not use PPA w/o proper training. Except we can't do proper training because we can't light up real contents in real houses for training. Burn buildings full of wood are not the answer. Less heat release, less smoke production, less volatility overall. I'm not against burn buildings because we have to use something. But they have limitations and everyone should be aware of what those limitations are as it relates to real world fire ground conditions.
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captnjak said:
Mike Gemberling said:I guess this discussion goes as I thought. To me it seems a very dangerous tactic for a dept our size that has never really trained on it. It was taught initially in FF2 but it seemed rather vague as far as how to read and when to use it. It would also seem ppa is a norm for some. I really do appreciate everyone's comments as I constantly want to learn and grow in this field. Well, I'm 46 but I think the old brain still has a few tricks left. Keep this discussion open please!
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I'm older than you and also still learning. At least I hope I am. The day I stop learning is the day they should throw me out. We either go forward or backward; no standing still.
I'm with you on the "vagueness" aspect. My first big problem is the size of the exhaust opening. No one agrees on the minimum but they all seem to agree that the bigger it is the better it is. Fine, but it's out of our control. The size of the window(s) in the fire area are pre-determined. What if they're just too small? Some say they then nee to be enlarged. Fine, but there is a time factor involved. While we're enlarging the opening(s) the fire grows. And grows. The victims wait longer and every second is vital to them. Meanwhile, the hose is still waiting at the entry point for the fan to get the heat out the exhaust point. Why not just use the hoseline to reduce heat immediately? (Personally, there is no way in hell I'm standing fast at the front door with a charged line while some guy tries to cut away the back wall of the house with a chainsaw so a fan can be used to reduce heat levels.) Plus, there is no way to know in advance how big is big enough. Same goes for the fan. How many CFM do we need to eliminate the amount of BTU's present. Who knows? How many BTU's are present? Who knows? What is the exact ratio between heat energy present and the CFM's required to exhaust it out an opening of the size we have created? Who knows? Can increasing the fan's capabilities make up for a smaller opening? Who knows?
I'll answer that. No one knows. And no outside survey is going to tell us. Nor will it tell us the layout of the building or the status of interior doors.
They tell us departments should not use PPA w/o proper training. Except we can't do proper training because we can't light up real contents in real houses for training. Burn buildings full of wood are not the answer. Less heat release, less smoke production, less volatility overall. I'm not against burn buildings because we have to use something. But they have limitations and everyone should be aware of what those limitations are as it relates to real world fire ground conditions.
My thoughts exactly. Although my department trains alot (very rural), we do not have the experience of real R&C fires. Because of where I reside our response times vary greatly/ 600 square miles to be exact. Alot of times it's going to be an exterior "cool it down" before anyone goes in. We get many creeping chimney/attic fires from woodstoves where PPA could blow the roof off the place. However I always value the other side of the coin from bigger inner city departments and since we have some training money available, I'd thought I'd ask about it. For us vertical, horizontal and if we are interior, hydro ventilation seems to be our best bet.Our fan is normally pulling the bad stuff out during mop and salvage.
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Permalink Reply by James Billings on
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Iv'e read most of the comments and agree with most of them, but here is one big thing that was mentioned TRAINING!
At my department as a young lad we was tought how to use the PPV (Blow) and the smoke ejectors uses( They Suck) not in a bad way either, and proper placement of both and uses.
that being said the PPV is the second thing that is pulled off the engine and is placed 10 feet or so from the door and is running at idle till the entry team is ready and gives the command to turn it in to the door way as they go in, this gives them some visual and cooling effect, and can improve victims chances by removeing super heated gases from the area.
the opening for the exhaust side of it is sometimes the window in the fire room its self or the closest rear door of a single family dwellings.
hold on before everyone gets bent out of shape, the use of ppv's is determined on that departments SOP'S, SOG'S and TRAINING!!!!!!!!!!!
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