Using PPV during fire attack

[Dave Page]

looking for information/experiences from those using PPv during fire attack vs. post fire (just clearing smoke from a structure)

[KenNFD]

The decision to use PPV here is up to the incident commander. When used properly, it a big improvment. Used incorrectly, and you can have a larger fire with injured firefighters. As in everything else, training and practice is needed before the fire.

We have also had good experience using PPV at car fires. Driver drops the blower about 10 to 15 feet away from the car. Location depends on where fire is of course.

------------------
Ken Hanks
Captain Naugatuck FD,CT
Instructor,CT Fire Academy

[LadderCo13]

In Indy we use PPV in conjunction with the attack crews inside with great success. There are alot of factors to consider, but basically when the attack sector is ready for PPV they get it. We have dedicated engine and ladder crews which also helps. The team concept truley comes into play when utilizing PPV while attacking the fire.

[Ricky Bodin]

We have been using PPV for about 10 years with great sucess. I would have to agree with the earlier post in that it takes some pre incident training and good coordination between the attack crew and ventilation teams. Also if the building is showing signs of backdraft or the fire is an attic fire it is best to use vertical ventilation through the roof. I would encourage your dept. to explore the use of this tatic.

[This message has been edited by Ricky Bodin (edited 02-21-99).]

[Phred]

SuperVac (makers of both positive and negative pressure fans and blowers) has a web site and a BBS for ventilation subjects. They also compiled a good text covering positive and negative ventilation.
Visit site at: www.supervac.com (http://www.supervac.com) .
BBS is reached at their "Forum" click.
-- http://www.firehouse.com/interactive/boards/smile.gif--

[Dryfus]

My FD has been using PPV for several years with good success by providing large fans on all engines and trucks. Our SOP call for the first in officer to hot lap the building, break out the hot window and call for PPV and fire attack. The key is to provide for and exit opening equal or larger than the intake opening prior to starting PPV. The best fan on the market we have been able to find is the Tempest 24” with a Tecumseh 5.5 OHV engine. This combination out performs all other 24’ and 27” fans on the market while maintaining a small outside profile. You will notice the greatest effect when multiple fans are used and placed in series.

[Brian]

Dreyfus did you mean to say that the exit opening should be smaller than where the PPV enters the building, in order to positively charge the building. Also I agree 100% on your choice of PPV fans. We have had 2 of those for 4 or 5 years and they work great. Our problem is that we normally don't use it in conjuntion with the initial attack but usually shortly after the initial knock down. Mostly because we always have our engine company working first. If you're not careful you can make the fire a lot bigger or have it break out in a void you didn't know about before. Also we have been using electric PPV during the final overhaul because we use air monitoring to determine when we go from SCBA to non SCBA overhaul and we have found that the exhaust from the PPV fan was exceeding osha pel for CO.
Brian

[CD]

Brian, I recently met with the owner of Tempest fans and he said their research indicates that the exhaust opening should be slightly larger than the intake. I bought for my FD several of the Tempest 24" belt driven fans with a 5.5 OHV engines which have been third party tested to out perform all other fans that I could evaluate. I have done some testing of PPV during fire attack at training burns and at incidents and have found that I could stop and sometimes reverse the movement of rollover within the structure. I am going to do some testing later this month to see if PPV can be used to combat the undesirable effects of steam production, extending fire to the uninvolved parts of a structure, during an exterior attack. If successful, this will allow firefighters to do and exterior attack when faced with inadequate staffing, to comply with 2 in 2 out. I will post the results.

[Brian]

CD:
I'm glad you replied. Apparently my training on PPV is outdated. I was basing my reply on classes we took in truck company ops given by Bob Mittendorf, this has been about 4 years ago.
Well I don't want to be one of the guys that always say "That's not how WE used to do it" Thats why I like this firehouse forum so much. It is great to network with so many fireman. It helps us to stop reinventing the wheel and start working on the car. I hope you plan on posting your findings on here so we can all benifit from it. Brian

[CD]

Brian, Tempest has an exhaust adapter to fit most of the small engines found on fans.The adapters are intended for use with flexible, stainless steel exhaust extensions. I have used a 10' extension and it eliminates almost all of the odor of exhaust inside the structure. Tempest sells the extensions as a kit, but I have found the identical tubing from Graingers catalog at half the price.

[This message has been edited by CD (edited March 21, 1999).]

[SBrooks]

FYI-OSHA PEL for CO is 50 ppm, TWA, which means that OSHA will allow workers to be exposed to 50 ppm for 8 hours a day for a 40 hour workweek; or to 100 ppm for 4 h/day, or 200 ppm for 2h/day. OSHA would actually allow 400 ppm for 1h/day. Of course you would get sick, at least with a headache, but as far a the regs, go, it's ok, for CO only. Safer yet would to use the REL of NIOSH, which is 35ppm TWA and ceiling value (not to exceed for any length of time) of 200ppm.

Also, CO is not the only toxic substance produced by the incomplete combustion of household products....but that's another story.

[1835Wayne]

I am up to NO good today.

LIVE LITTLE THREAD!!! LIVE!!!!!

[mrivers09]

maybe it's just because i live in the south but i have seen airboats used as ventilation fans and they work like a dream!

[kd7fds]

I know this is an old topic, but I just had some new information on Friday that is applicable.

I was at the NFA last week and had a Battalion Chief from the FDNY in my class. On Friday morning the instructors gave him some time to talk about research he has personally been involved in for the FDNY on two topics.

1. Use of PPV to control smoke in high-rise fires
2. Revised tactics for handling wind-driven high-rise fires.

He gave us preliminary results from some of the FDNY's and NIST tests that were held on Governors Island regarding wind-driven fires and tied it in with previous tests down in Chicago and Toledo. This particular BC was involved with all the tests.

He went into the Toledo testing as a PPV skeptic, wasn't convinced but after the Chicago tests, was a convinced. This years Governors Island tests cemented his belief that it is an important tool.

His Battalion is part of a pilot test in the FDNY to use PPV for high-rise fires.

He isn't convinced that it will be a good technique for every type of construction out there. He wants to see more testing. He is a career truckie and has always lived and breathed verticle ventilation.

He was really impressed on the Governors Island tests though, he said that combined with some of their wind control techniques plus PPV coming from the stairwells, they could go from 2000F temps in the hallways to almost ambient conditions in less than 2 minutes so that the guys could basically just walk in and put the fire out.

NIST will have a CD out probably by the end of the year with the official results from their wind driven testing.

One thing I can share though. Its something that my volunteer department has done for a long time and NYFD figured out how to apply to high rise fires.

If you apply just enough water from outside the window into the fire room to brown out the fire, you can then make an aggressive interior attack and finish putting it out relatively easily. In the FDNY testing they found that they didn't push the fire like they expected it too.

[dmleblanc]

He isn't convinced that it will be a good technique for every type of construction out there. He wants to see more testing. He is a career truckie and has always lived and breathed verticle ventilation.

.


He shouldn't be because it's not a good technique for every type of construction. It's not the best technique for every fire, even given the same type of construction. It has its place under certain circumstances. I am very familiar with its use in single family dwellings...we have been "testing" PPV use (in other words, using it at actual fires) for over 15 years.

I have no idea how it would be applied in a high rise...I imagine you'd need some hella big fans to pressurize a space that size, probably some truck-mounted airboat sized stuff. I know it works well on SFD's.

One good thing I can see coming out of this....maybe if FDNY adopts PPV, it will finally be an acceptable practice for the rest of the naysayers to give it a try :rolleyes:

[kd7fds]

Suprisingly, the fans they are using aren't that big.

They are using 27" 24000 CFM fans to pressurize the stairwells to 20pascals.

They set the fans 4 feet from the stairwell door, tilted 10 degrees from vertical.

If the building is more than 15 stories tall, they set a fan every 12 floors pointed at the stairwell door, not in the stairwell, but outside it to maintain pressure. This level of pressure can be maintained with up to 3 doors open with no fan.

They were worried about CO levels as well. They don't see readings above 100ppm CO in the course of operations.


I'm from a volunteer department in Idaho, we have been using PPV for a long time in all sorts of different structures.

Over time, I have seen a lot of discussions on the board about PPV. I found it interesting that FDNY is now finding applications for PPV where they admit it is the best thing they have tried and actually improves fire floor conditions when applied properly.

PPV isn't the end all be all of ventilation either. Its another tool in the toolbox. I think people who don't use it know, would be suprised how well it works if they test it out. If they get the right training first so that they know what to do and how to do it safely first.

[RFDACM02]

One good thing I can see coming out of this....maybe if FDNY adopts PPV, it will finally be an acceptable practice for the rest of the naysayers to give it a try :rolleyes:I think that you'll find that some of the PPV pioneers, like LA City, are really mostly using PPV in highrises now. In the case of highrises, my understanding is that the PPV is used to pressurize the stairwells limiting the smoke intrusion to them as people make their escape. This could also be used in the attack stairs I'd surmise. I sincerely doubt you'll see FDNY using PPV in non-highrise construction.

[sfd1992]

I am up to NO good today.

LIVE LITTLE THREAD!!! LIVE!!!!!

Damn You!!! If you had waited 6 more months it would have been 10 YEARS!!!!

[HCFD49]

In single family dwellings PPV is a great tool when used right. some people dont get it.

[jonnyirons2]

Our fans at work are now being taught job wide as a tool for wind driven fires and fires in hi rise buildings. The advantage it brings is that it pressurizes the stairwell and reduces the punishing conditions that occur from wind driven fires. Couple the fan with a fire blanket and its a good solution.

[Engine1FF]

When used correctly they work good. I was in a SFD structure fire with heavy smoke and moderate heat. We were trying to find the seat of the fire and the PPV was started. All of the exterior windows were broken out by the Truckers prior to that. When the fan started it changed the conditions from bad to worse. The heat dropped everybody to the floor and when command did an emergency evacuation the house flashed on us as we were bailing out of windows and doors. Ever since then my department has backed off on the use of PPV.

[ffmedcbk1]

Damn You!!! If you had waited 6 more months it would have been 10 YEARS!!!!

this is the little thread that could...
http://www.rdstore.com/sitemedia/product/extralargeimages/08519al.jpg

[dmleblanc]

We were trying to find the seat of the fire and the PPV was started. All of the exterior windows were broken out by the Truckers prior to that. .

Yep, that sounds like improper application to me. Once you break all the windows out you can't pressurize the building, so it won't work properly from that perspective. Furthermore, PPV will cause the fire to flare up somewhat. That's why it's important to have the crew at the door ready to enter when the PPV is cranked up...they'll basically advance behind the retreating heat and smoke. If they were already inside, maybe BEYOND the fire when the fan was applied, then yeah, they probably got some fire and heat pushed toward them.

[cubbie]

There are two chiefs out in the Denver area that are teaching PPV application little different. They do a walk around to find the fire if they can. They break a window closes to the seat of the fire. Then start the PPV at the fire crew entry point. They wait for the smoke to clear then make entry. Their test data seems to be sound. The theory they teach is that by breaking the window closest to the seat of the fire you create and exit point for hot gases and smoke. Starting the PPV forces all the products of combustion out that window thus preventing fire spead by lowering the temperture in the stucture. I have seen there test videos. I would like to see it live. They did an on-line class here on firehouse.com.

[dmleblanc]

There are two chiefs out in the Denver area that are teaching PPV application little different. They do a walk around to find the fire if they can. They break a window closes to the seat of the fire. Then start the PPV at the fire crew entry point. They wait for the smoke to clear then make entry. Their test data seems to be sound. The theory they teach is that by breaking the window closest to the seat of the fire you create and exit point for hot gases and smoke. Starting the PPV forces all the products of combustion out that window thus preventing fire spead by lowering the temperture in the stucture. I have seen there test videos. I would like to see it live. They did an on-line class here on firehouse.com.

That sounds like a textbook explanation of how it is supposed to be done. If anyone out there is doing it much different from the above description, that may explain why they're always complaining that PPV doesn't work :rolleyes: . If done as described above, it should work. We do it all the time.

[RFDACM02]

That sounds like a textbook explanation of how it is supposed to be done. If anyone out there is doing it much different from the above description, that may explain why they're always complaining that PPV doesn't work :rolleyes: . If done as described above, it should work. We do it all the time.
I was think the same thing, anything but that way would seem to be the problem.

Legit Question: Do you not use PPV when the fire area is not directly vented to the outside? What if the fire cannot be "found" from the outside?

[dmleblanc]

Legit Question: Do you not use PPV when the fire area is not directly vented to the outside? What if the fire cannot be "found" from the outside?


That's an interesting question...I guess I've never really thought about it because most (like "all") of our fires are in fairly small single family dwellings. It's usually not too hard to figure out where the fire is, and it's usually in a room that has an external window or door for an exit vent. Also, a quick walkaround with a thermal imager (if you have one) can show you pretty easily which room is "hot".

[AFDFS24C]

If you cannot determine the location of the fire from the exterior after looking at all sides of the structure you shouldn't use PPV.

Locate the fire, create an exit opening as near to fire as possible, place the fan in the point of ingress, let the interior conditions lift for 15-20 seconds, make entry.

[bcarey]

That (RFD's question) would depend on the structure and what natural vents are available. In the Pennsylvania burn building tests with no open windows to the fire room, while the fire did not extend, the combustion gases traveled to adjoining areas or stairwells and floors above seeking out a natural vent opening. There are many variables that we need to read and understand. One from that test is should we reconsider when we open up the bulkhead door?
http://fire.nist.gov/bfrlpubs/fire06/art066.html

The Toldeo school test showed that you could use PPV to pressurize a long corridor, without pulling the fire gases or pushing the fire. In this test, a fire was set in the gymnasium. Fans were set up at a doorway of a far, but connected hallway and pressurized the hallway. When the fire in the gymnasium flashed, it did not extend into the hallway due to the cooler temperature and increased air pressure being brought in. The halls also were kept clear. The purpose of that test was to see if, with limited staffing, crews could use PPV to remove, or hold the hazard, while evacuations took place.
Evaluating Positive Pressure Ventilation In Large Structures: School Pressure and Fire Experiments (http://www.fire.gov/PPV/index.htm) In that test, they found that fire conditions actually worsened when the gymnasium roof was first vented and then the fan was turned on.

We need to understand the importance of the fan placement and the specifics of pressurization, as well as the thin line between "venting" and "cooling". They're not the same.

[Catch22]

There are two chiefs out in the Denver area that are teaching PPV application little different. They do a walk around to find the fire if they can. They break a window closes to the seat of the fire. Then start the PPV at the fire crew entry point. They wait for the smoke to clear then make entry. Their test data seems to be sound. The theory they teach is that by breaking the window closest to the seat of the fire you create and exit point for hot gases and smoke. Starting the PPV forces all the products of combustion out that window thus preventing fire spead by lowering the temperture in the stucture. I have seen there test videos. I would like to see it live. They did an on-line class here on firehouse.com.

Are you talking about Chiefs Garcia and Kauffmann from Salt Lake City? Close enough to Denver, just clarifying if it's the same guys or not. If so, they've got a webcast (http://www.fireengineering.com/webcasts/index.html) on the Fire Engineering site (bottom one on the page) that's got a lot of good information on it.

When my career department decided to go with using PPV on attack, this webcast was the "introduction" to the process.

PPA/PPV is just another tool, but one that we had a helluva time trying to get guys to understand. It's also a dangerous tool if used wrong, as one crew almost found out when they opened a single rear door as the ventilation opening only to have it close after they walked away. The pressure built up inside and pushed right out the door where the fan was, over the cone of air from the fan.

Once we got our guys to grasp the concept of pressure, it was a lot easier. Fire can create upwards of 10 psi of pressure. That pressure is going to find somewhere that there's lower pressure to escape to. If you use a PPV fan to "pressurize" the compartment/structure beyond that of the fire pressure, you're going to push everything to the next lowest pressure zone (your vent opening). The bigges problem is making sure you have a big enough opening to get the pressure out.