Does anyone know if there is widespread use of PPV fans on a going fire?
I was asked about a US trial whereby a fan is used on a fire still burning in a structure and the theory behind it is that the temperature is reduced. Can anyone shed any light on this?
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Thread: PPV Fans
06-19-2001, 10:47 PM #1pentsFirehouse.com Guest
06-19-2001, 11:05 PM #2TriTownship600Firehouse.com Guest
It will reduce the temperature inside the structure but, it will feed the fire oxygen. The fire will grow at a very accelerated rate. You must get water on it quickly.
We don't use PPV during the attack. It does work very well to clear smoke and heat following the knock down.
Some will disagree with me but, that's my 2 cents worth.
Stay Safe, God Bless
06-20-2001, 02:17 AM #3Lt.HouckFirehouse.com Guest
Some departments use this tactic with alot of success. The change in conditions on the interior is incredible. However a hoseline must be in place and ready to go before the fan is placed into service.
We don't use it in our area do to a large amount of balloon frame type constructed houses. These houses have walls with open stud space from the attic all the way to the basement. Most of them are 70 to 100 years old. When ppv is placed into service before the fire is knocked down and extension is controled, it tends to cause the fire to blow up the walls and straight into the attic.
06-20-2001, 02:29 AM #4RLFD200Firehouse.com Guest
Although the dept. I am on does not practice this tactic there pros and cons to the PPV being used on a working fire. Yes the temp. is reduced, but the smoke is also reduced and vision becomes much better. We have to remember life safety is #1 priority. If you can see well enough to do a search and possibly save lives, thats fantastic. As mentioned above a hose line must be in place.
06-20-2001, 12:11 PM #5Dalmatian90Firehouse.com Guest
PPV is incredibly popular in some communities, used after the fire in others, and not at all in others.
We use it heavily on single family, newer residences -- they have sheetrock walls and fire stops in the framing. For most fires, it's simply an extension of the older tactic of using a narrow fog to push the fire out of the fire room through a window or roof opening. While it may intensify the fire, it makes finding the fire, stretching lines, and conditions behind the attack team more tenable. And while it may intensify the fire, it also pushes that fire away, which if "away" is out a vent hole is a better thing usually then letting the fire spread throughout the building.
With careful consideration, we might use it on the older housing dating from the 1700s to mid 20th century. Probably would use it with the few newer masonry institutional buildings built under the the good fire codes now around, if the fire size/location/conditions indicated.
But even as you move into the eastern parts of town, large multi-family balloon frame housing starts to predominate, and it's a big risk of extending a fire through the balloon voids -- so PPV is used more as an overhaul tool once troops and hoselines are in place all around in case the fire flares up.
As you move into the old Northeastern Cities, with large buildings, high life hazards, and numerous different building styles PPV becomes less of a viable tactic -- there's too many variables to consider, and these departments typically arrive with sufficient manpower sufficiently quickly to use very aggressive search tactics that are incompatible with PPV and fog tactics.
06-20-2001, 04:01 PM #6HallwaySledgeFirehouse.com Guest
Pents, grab two of your biggest guys, have them each take a side of the fan, get two or three good swings in and then have them throw it through the biggest window on the structure. Just my opinion on how the ppv should be used. Like Lt. Houck my area's construction is old and has a lot of balloon frame. A lot of the older homes have been rehabbed numerous times as well, leading to many hidden voids. I've responded to posts on this topic in the past and around my area the ppv fan is used AFTER extinguishment during the overhaul stage to clear the atmosphere, not as true ventilation during an attack operation.
The opinions expressed herein are my own and do not reflect those of my Department or it's Administration.
06-21-2001, 02:37 PM #7gah74Firehouse.com Guest
Pents... I think you will notice that when people disagree on issues such as nozzles, PPV, and other tactical considerations...a lot of times the individuals are from totally different regions and fight totally different types of fires.
Most of the fires we fight around here are similar to what Dalmation90 was talking about. Newer suburban homes w/ sheet rock and fire stopped joist walls. In fact, I think you would be hard pressed to find a balloon frame bldg anywhere in the city I work in. We have a lot of success w/ PPV in these newer homes, but consideration still must be given to where the fire is located. If the fire has broken through the ceiling and is in the attic, vertical ventilation is going to be necessary. However, if the fire is limited to a bedroom and is venting out a window, the PPV is awesome. For example, say you have an attached garage in the rear of a house that is on fire (pretty common around here). Fan at the front door started as the first line goes in...first line goes straight to the garage. 2nd line right behind them pulls ceiling and goes to attic. Works like a champ for something like that.
06-30-2001, 08:22 PM #8
It seems like a lot of people advocate post knockdown use of PPV. It seems to me, PPV, if used at all, should be terminated before the first void is opened during overhaul. If we open a void while standing in a pressurized compartment, little or nothing will show in the hole besides char. All smoke and any fire will be forced into the opening and towards whatever path the air movement takes.
A small, one room fire with limited encroachment into the voids could turn into a nightmare as our own air movement pushes fire up, over or around us.
I f you really feel PPV is a viable fire tool, use it. I would strongly suggest it be discontinued prior to overhaul and opening up of walls and/or ceilings.
07-01-2001, 12:32 AM #9
- Join Date
- Mar 2001
- West Jordan, Utah, USA
E229lt makes some good points. We use PPV on every fire. It is done after a proper size up and in a co-ordinated attack with the nozzle team. One thought to go along with E229lt's thoughts about how it keeps the heat in the void spaces making it difficult to do a proper overhaul; try using it to assist exposure protection. For example you have a strip mall fire in one business, use PPV in the two adjoining businesses to assist with keeping the fire, heat and smoke from entering them. Works wonders.Firefighter/Paramedic Ron Sanders
Midvale Fire Department
Medic Ambulance 22 - A Platoon
Firefighters, Walking where the Devil Danced!
This is simply my opinion and does not represent the opinion or view of my employer(s) or any department/agency to which I belong.
Personal Website: http://RonSanders.Biz Check it Out!
07-19-2001, 03:08 PM #10
- Join Date
- Feb 2001
- Conshohocken, PA
All good posts. Just some other points to consider.
1. Train, train and train some more. This can be a very difficult and dangerous tactic if not used properly. Train in aquired structures, not a burn building.
2. This tactic while used very effectively, can just as quickly turn a successful knockdown into a very significant loss. Once the fire has been knocked down, finish it off quickly. If you can't do that, you better turn the fans off or direct them away from the supply vent.
3. Remember you still need two openings just as in conventional ventilation. One for the bad air and one for the good air. When using this, normally the location of the fire should be well known. A clear ventilation path to the outside should be secured and vented. The fan should then be directed into the supply vent hole. Beware of the fire, smoke and products of combustion that come out of the bad air vent hole. It will be like h*ll on earth when it comes out. If you then develop a problem with the hoseline and/or you have exposures close to the discharge vent hole your gonna spread the fire to the exposures very quickly.
This is another reason why many of us here on the east coast don't like using PPV in the attack mode. Our buildings are closely spaced and the exterior coverings are as flammable as the interior finish.
If you are considering using this tactic in the fire attack mode, get someone who has used it successfully to train you. The training should include hands on. Salt Lake City, Utah has been very successful with this technique in the attack mode.
Good luck and be safe.
07-19-2001, 06:30 PM #11
- Join Date
- Apr 2001
- District of Columbia
PG county uses them post knock down, typically after the trucks have checked for extension (opening the walls), but before all of the hook-work is done.
I'd like to see them used on the initial attack in FR / NC high rise buildings, as well as previously mentioned in strip malls.
It seems that in gah's scenario, it would work well.
We typically use tactics that are very simple to understand, and don't usually have to change them depending on the type of building we show up at.
08-16-2001, 08:10 PM #12
- Join Date
- Jul 2001
- Houston area
We try to get PPV established as soon as possible to increase visibility and decrease smoke and heat conditions. The most important thing to consider is whether the attack line is in position for knockdown. If they're not, you will end up feeding the fire. There is a trade off somewhere in here between knockdown and visibility. With ventilation in place, you can theoretically find fire more quickly and efficiently. As of recently, we now have thermal imaging cameras on all of our front-line pumpers. As of yet, there hasn't been any kind of SOP change regarding ventilation, but I would assume that PPV could be delayed with the use of these cameras, since visibility may not be as big of an initial concern.
There's not much out here that is older that 25 years old, so the construction we're dealing with is not baloon type, and generally doesn't have a huge amount of void spaces to speak of.These are my opinions and not those of the organizations for which I work and/or volunteer.
08-16-2001, 08:24 PM #13
- Join Date
- Nov 2000
- Detroit Mi
I used the fan just the other day we had a good basement fire the truck that i drive pulled up right behind the engine while the engine crew got ready to go in i placed the fan right behind them on the inital attact it worked so well the guys could not believe how fast the smoke and heat were off them. Thats was of course a basement window was poped out on the other side it has to be a group effort for it to work.
08-16-2001, 08:44 PM #14
- Join Date
- Jul 2001
We use ppv on almost every call at one point or another, but it should not be used prior to knockdown and your sure there is no extention, for the obvious reasons already stated. Dalmation, you need to be very careful that while pushing the fire "AWAY", away is not toward any victims, or the truck co. performing ves. Another thing to consider when deciding to use ppv during an attack, is if there is a lot of smoke but the fire is not imediatly found, then the combination of senses needed to find the fire quickly is lost, by that I mean you cannot get down to the floor and check the source of the smoke and possible direction of travel, you will no longer be able to feel where the heat is comming from, and you probably cannot hear anything but the fan. Hate to bore youz anymore so for now stay safe.
08-17-2001, 12:25 AM #15
- Join Date
- Aug 2000
- mckinney, texas, 75070
Rules for PPV
1. NEVER use until seat of fire is located
2. NEVER use in an attic fire
3. NEVER use when venting can't be assured.
4. Know the location of interior crews
5. Properly used and trained with it is the interior firefighters best friend.
08-17-2001, 03:44 PM #16
Dalmation, you need to be very careful that while pushing the fire "AWAY", away is not toward any victims, or the truck co. performing ves.
Which is why the last line of my post was
very aggressive search tactics that are incompatible with PPV and fog tactics.
We don't do VES out here. Wouldn't work with our normal set of tactics, and there isn't much need for it in our typical buildings/occupancy/fire situations.
PPV or VES is very dependent on your local conditions!IACOJ Canine Officer
08-17-2001, 07:14 PM #17
- Join Date
- Mar 2001
- Madison Wi 53705
Before you look at using PPV you must consider the place were it was developed. The US navy developed it for ship board firefighting. They can control all points- Enterance, Exit and auxilliary vents. When using it for structure fires you must know atleast 2 things. 1- Where is the fire, and 2 Where are the victims. Since we never know where the victims are. You see the reason to reduce the use of PPV on the initial fire attack.
08-18-2001, 10:39 AM #18
Fire Chief, "Everyone out?"
Resident, "Yes, we're all out"
Gee, we know where the victims are. Yes, we can trust reports like that in our district -- other areas may have different socio-economic conditions, but in our area if your told they're out, that's reliable information.
Fire Chief sees heavy fire blowing out one window, none if any smoke from other windows, or a particular pattern -- fire from fire room; smoke from kitchen & living room that are connected by hall to the fire room. No smoke from other bedroom windows. Hmmm, bedroom doors are closed so they're safe *if* anyone is there; the heavy fire in bedroom is inconsistent with human life. PPV into the Kitchen/Living room that someone has a good chance of surviving in will make those areas more tenable faster than you could search them, and the fire room is already fully involved so it's very unlikely to have life in it, and the fire's already there so your not pushing it on the victims.
Yes, you need to know where the fire is. If you know there are no victims, that's no longer a consideration. Even if you know there is victims, the fire location still dictates the usefulness of PPV. If it's a room & contents or other fairly isolated & well vented fire -- PPV it. Removing the fire gases the quickest and knocking down the fire the fastest improves the odds for the victims remote from the fire, and those in the fire compartment already had very low probability of survival, and PPV won't make their situation worse.
Now if you have fire in the say, living room, with victims/possible victims in the bedrooms you don't want to blow the fire in that direction!IACOJ Canine Officer
08-18-2001, 03:58 PM #19
- Join Date
- Dec 1999
While the department I work for uses PPV after knockdown most of the time, I've recently been studying up on it's use as a initial attack tool.John Mittendorf provides excellant material on this subject. A few observations I've noted:
1. Balloon Framing- PPV is o.k. when a proper exhaust opening has been made. hence the pressurized smoke will follow the path of least resistance not pressurize the stud bays.
2. PPV must be COORDINATED with attack and vent.
3. VES and PPV do not mix.
4.Before the line advances and the fan is introduced, the exhaust opening must be made.
5. Location of the fire and occupants can be a reason to use or not the PPV tactic.
It seems PPV has been widely misunderstood,and has been proven to not work in some areas-(many places where windows are all open due to climate make it so the exhaust cannot be controlled) Departments who just start the fan and point it in the building as soon as a firefighter has time are not using PPV correctly.
This is the only opinion to have, if you're me.If not, get your own this ones mine.Lt.ACM
08-19-2001, 09:26 PM #20
- Join Date
- Jul 2001
Interior to command fire knocked down situation under control, start the fan... command copy..... command to interior appears there is fire in the attic do you copy?..... command to dispatch gice me a SECOND ALARM. Dalmation, if it's a room and contents fairly isolated and well vented---ppv it? I DON"T GET IT.
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