1. #1
    Junior Member

    Join Date
    Feb 2000
    Location
    Albemarle County, Va
    Posts
    12

    Default When do you use PPV/NPV?

    This may be a topic thats already been beat into the ground but I'd like to hear from others about how they do things/what they have seen done.
    The departments I have been around and seen use forced vent. for the usual food on the stove/shut flues/burnt motors ETC. and AFTER the fire is out/salvage time.
    How many people use/have seen used forced air vent. DURING fire attack or the earlier stages of the incident? Obviously there are the details of hoselines properly placed yada yada but is this practiced as an SOP/SOG in any depts?

    Just trying to learn some new ideas



    Career or volunteer, we're always professional
    Seminole Trail Fire Dept.

  2. #2
    Junior Member

    Join Date
    Jul 2002
    Posts
    6

    Default

    The department that I work for has been using an Offensive Fire attack with PPV for a year or so now with good success. Some of the things that I consider before I will initiate this type of tactic are:

    * Type of construction
    * Location and size of fire
    * Is there extension into the attic
    * Has the fire already vented through a window or do I need to provide an exhaust port

    One thing that I highly recommend before this tactic is attempted in the field is to train with it first.

    Some of the difficulties that we experienced when we first started were:

    * Coordination between the person that will be opening the exhaust port (if needed) and the Fire Attack team. It is very important to make sure you have that opening before you turn the fan into the doorway.
    * The Fire Attack team had a tendency to set the fan, then make entry. You need to give the fan some time to do its job, and getting the Fire Attack team to wait 15 - 20 seconds before they make entry took some getting used to.

    Anyway, its a great tactic when done properly and works extremely well. The first time you see it done, whether on the drill ground or in the field, itís very impressive.

  3. #3
    Junior Member

    Join Date
    Feb 2000
    Location
    Albemarle County, Va
    Posts
    12

    Default

    ok folks..I know I'm not the only one curious or hsa info on this subject....
    Seminole Trail Fire Dept.

  4. #4
    Member

    Join Date
    May 2002
    Location
    Earth
    Posts
    32

    Default

    I've used it (PPV) on three separate departments. The previous reply did a wonderful job to talk about using it based on building construction, stage of fire, etc. I might also add that you need to consider fire location (if it's in the front then it will push the fire/heat to the vented area, if that's in the rear... that's bad or if there are unknown voids based on construction type that is likewise bad), experience of vent crew (using PPV without knowledge can be catastropic), who is inside and where can be impacted by PPV. The last point that I wouldn't discount is using PPV to measure knockdown extension. On more than one occassion we have pressurized a house (that was suspected to be extinguished) and discovered that smoke was evident elsewhere (usually an attic or wall). For many having an adequate crew is necessary; you need... pump operator, 2 in, 2 out, PPV operator, and vent person (often with backup if it's roof vent)... this is a total of 7 to 8.

  5. #5
    Member

    Join Date
    May 2002
    Location
    Earth
    Posts
    32

    Default

    I've used it (PPV) on three separate departments. The previous reply did a wonderful job to talk about using it based on building construction, stage of fire, etc. I might also add that you need to consider fire location (if it's in the front then it will push the fire/heat to the vented area, if that's in the rear... that's bad or if there are unknown voids based on construction type that is likewise bad), experience of vent crew (using PPV without knowledge can be catastropic), who is inside and where can be impacted by PPV. The last point that I wouldn't discount is using PPV to measure knockdown extension. On more than one occassion we have pressurized a house (that was suspected to be extinguished) and discovered that smoke was evident elsewhere (usually an attic or wall). For many having an adequate crew is necessary; you need... pump operator, 2 in, 2 out, PPV operator, and vent person (often with backup if it's roof vent)... this is a total of 7 to 8.

  6. #6
    Member

    Join Date
    Jul 2002
    Location
    League City Texas
    Posts
    61

    Default

    It's an excellent techinque when used correctly which has been well described in the various post. We've been using PPV for about 10 years now.

    One thing that I highly recommend before this tactic is attempted in the field is to train with it first.
    This was the best thing said because if you don't do this all those bad things mentioned can make for a really bad day.
    Stevejd
    www.lcvfd.com

  7. #7
    Member

    Join Date
    Dec 2001
    Location
    Florida
    Posts
    41

    Default

    I guess I have been beating this horse to death for the past 20 or so years.
    PPV is an excellent tool or procedure for the task (tactic) of removing byproducts of combustion after the fire is under control.
    Aside from that it's excellence can only be accessed when it iw used in relation to a thorough size up.
    1. The fire is in a room at the building corner so that two sides are outside walls AND it is determined by failed search or by total involvement that no savable human being could be in that room. Almost all articles on PPV in combustible buildings put the fire in this room! Ask the authors to put the fire in the middle of the occupancy!
    2. If the fire area is between the nozzle (fan) and unburned portions of the structure (dwelling) then that area must be searched or otherwise confirmed to be free of human beings. Fire will scream blow torch fashion through any unburned area in the path between the fire and where you choose to put the opening (to complete the evolution)
    This area of dwellings is knows as the "rear of the fire" and is the area in which occupants die if not found even before water is started in the nozzle. (The rear is where the nozzle will push the fire as will the fan)
    But then those that use PPV in occupyable structures with the nozzle usually have no knowledge of this area or its hazards or its rewards of being the location of the "real" rescue in the structure fire.
    3. Excellent assist to ventilation in fires below grade also. In the past all we could do is to cut a hole over the cellar near a large window on the first floor.
    4. Watch out for the carbon monoxide in light conditions. We almost knocked out the training group doing team search from this invisible hazard.
    But - as always - Do what you want

  8. #8
    Member
    SquadHog's Avatar
    Join Date
    Dec 2001
    Location
    Urban East Hogville
    Posts
    76

    Default

    111Truck:
    I couldn't have said it better. Thanks for the straight forward, common sense post. You nailed it as usual.

    Oh, and please keep on "beating that horse," we need more hard-nosed, old school truckies around here.
    "Go ugly early."

  9. #9
    Junior Member

    Join Date
    Jul 2002
    Posts
    6

    Default

    Just a couple more thoughts on the benefits of using ppv for fire attack. I agree with 111Truck that a thorough size up is necessary before you use ppv in conjunction with fire attack.

    When I make a 360 around the structure there are certain things I'm looking for. I named a few of them in a past post, but here are some other considerations that I take into account. There are others, but I will post them at another time.

    Location of fire - Is this a room and contents fire? Do I have smoke and heat through out the structure or is it one or two rooms?

    Is there any value to be saved? Both life and property - I know life always comes first, but I will explain why I consider both at the same time. If I have a room and contents fire with smoke and heat confined to one area, and no extension to the attic space, there is an excellent chance that someone may still have a tenable atmosphere to survive in if they are trapped in the house. There is also property value so I will not hesitate to make an aggressive interior attack using ppv. I can control the flow of smoke and fire if I control the exhaust opening. I will risk a lot to save a lot, and when you send crews on an interior attack, you are risking a lot every time.

    Now lets change the scenario. I make my 360 and every room is charged with smoke. The windows are cracked and the window coverings have melted. This indicates a lot of interior heat to me. There does not appear to be any extension into the attic space. Again I will ask myself, is there any value here, both life and property? As for the life question, I would have to say that any chance of survival is very slim in that atmosphere. Is there still a chance that someone may be alive in there? Maybe. Value to the structure? It will have to be gutted and rebuilt from scratch so I say its minimal. On the chance that someone is alive, I will initiate an interior attack with ppv in this instance even if I donít know where the fire is for the following reasons. Again, you need to control the openings. If I can clear the heat and smoke it makes the interior crews jobs easier, they can perform a primary search faster, locate the seat of the fire faster, and I greatly reduce the risk of a flashover which is a benefit to the crew and the possible victim.

    I know that arguments can be made that I will be pushing the fire to the victims or throughout the structure. But let me ask you this. If there is minimal value left to the structure, and there is that much heat and smoke damage, how much more fire damage will the fan cause compared to what's already been done? Remember for this scenario there was extreme heat and smoke through out the structure. As for the life issue, that's a judgment call that each company officer will have to make. I will error on the side of my crew and provide the safest atmosphere that I possibly can for them to work in. I know thatís not going to be a very popular answer, but I will not risk a lot to save nothing.

  10. #10
    EuroFirefighter.com
    PaulGRIMWOOD's Avatar
    Join Date
    Jul 1999
    Location
    UK
    Posts
    831

    Default

    There are some excellent replies so far to this topic offering advice on pre-attack PPV applications (PPA). These words of wisdom demonstrate that 'experts' in PPV do not exist. I say that as so many have tendered advice in the past and proposed themselves as such! However, in this case the words clearly demonstrate the experiences of the users and I find myself agreeing with most that they say. There are however conflicts with normally accepted procedure although these conflicts offer 'food for thought'.

    Fosters offers sound practical advice but suggests that he might use PPA in situations where the fire location is unknown - breaking a golden rule! It is generally stated in training manuals that the fire's location should be known prior to using PPA. However, he goes on to describe a common fireground scenario but places the safety of his crews at the forefront of his decision - bravo! There is a lot to be said for that theory and perhaps he has had several good experiences using that approach - we are all conditioned to act based upon our own personal experiences. However, it is possible also that such an approach could actually worsen conditions for firefighters if an exhaust vent is made in the wrong location, pulling heat towards them at some stage.

    I find myself agreeing with just about all that 111 Truck proposes and would ask his opinion on recent research in the UK that examined victim location, inline with PPA. This research (using temperature loggers at victim location) suggested that conditions were not worsened at the victim's location where sited in that zone between the fire and the exhaust vent! I am not so sure about that but you can access this research at http://www.firetactics.com/PPV.htm

    A while back we debated on a thread here about a conflict between VES tactics and PPV - you may want to consider that point where firefighters using Vent and Entry tactics to search exterior rooms are placed into that 'zone' between fire and outlet vent - any forced airflow (PPA) is likely to conflict with their approach.

    In the UK there are several fire brigades now using PPA with reported success whilst most others are using PPV post-fire. Some are using PPA in 'defensive' fashion - isolating the fire room (not attacking the fire) before venting out the remainder of the structure - a strategy still being explored. Much of this work is being supported by three european universities who are looking closely at the dynamics of PPV/PPA.

    As said before - train hard and understand fire behavior fully before approaching PPA (Positive Pressure Attack).

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Log in

Click here to log in or register