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Advances in Fire and Rescue Technology?
He Definitely Didn't Inhale asks: "As anyone could imagine, being trapped inside a burning building would be terrible, but people risk their lives every day to save people stuck in that situation. While fire sprinklers are installed in some buildings they are far from ubiquitous, and also tend to cause plenty of water damage during their use. Some server rooms are isolated and can be filled with an inert gas in the case of a fire, but people - and fire - need oxygen to live. Another idea has recently been patented (USP#6,446,731), whereby a truck mounted high capacity fan is used to remove smoke and heat from burning buildings through the use of an extensible tube. This could make it much easier and safer for firefighters to rescue building occupants and put out the fire. Are any similar technologies or methodologies in use today? What are some design issues that may need to be resolved before this concept can be used safely and effectively? Are there any reasons not to pursue the development of this potentially life-saving idea?" Earlier this year, Ask Slashdot discussed Halon systems. Folks interested in this topic may want to give that previous article a read.
Oh yeah, I should probably also say that while PPV is a valid technique, and what I think one of the parent posts was referring to, it's NOT what the patent is referring to, as best as I can tell. The patent seems to clearly state that the idea is to suck the fire and gases OUT using a vacuum, which is the exact opposite of PPV.
My considered opinion is that the "inventor" of this particular device doesn't know much about firefighting, if he seriously intends to try to fight fire this way. Doing it this way, would most likely just make matters worse, as several people have pointed out.
Of course, he could turn it around, and he'd just have a truck-mounted PPV fan.
Then again, ventilation fans already exist for doing both positive and negative pressure ventilation, and I question whether simply truck-mounting it either way, is sufficiently different enough from existing practice to justify granting a patent anyway.
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My big question is, how do you deal with structural failure in the burning section?
That's a HUGE question facing the fire service, whether you use PPV or not. There are really three basic techniques to handle that issue.
1. size-up, and make a determination if an aggressive interior attack is feasible in the first place. If there are signs of imminent structural collapse, go defensive mode, "surround and drown."
2. If you initiate an interior attack, allow a certain amount of time (varies from dept. to dept, but for example, let's say 10 minutes) from the time interior attack is commenced... if the fire isn't contained in that amount of time, pull-out, and switch to defensive mode.
3. teach firefighters and officers to recognize certain signs of impending collapse. This is why one of the courses required for FF certification is something called "Building Construction." Firefighters are taught in a fair amount of detail how buildings are put together, and how the stress of a fire works against the building's construction. This helps them to recognize warning signs. It's also part of the size-up process I mentioned in 1 above. Recognizing balloon-frame construction as opposed to heavy timber construction for example, is a factor in determining the likelihood of a collapse. Another example would be recognizing the presence of pre-fabricated trusses, which are considered by many in the fire service to be one of the greatest dangers around.
Oh, and pre-planning also comes into play. Can't forget that. Fire Departments usually visit most commercial buildings in their districts on some regular basis (annual, for example) and one of the things they may note down for reference, are details about the building construction (plus things like where the fire department connection for the sprinkler system is, the closest fire hydrant, etc.)
It would seem pushing fresh air into a burning section would help consume more fuel (i.e. the wood holding the second floor from falling on your head).
Yes, there is something to that. PPV is not a magic bullet. It's use has to be taught, and firefighters and officers have to understand where , when and how to use it, and the ramifications of doing so. Used properly it can be a HUGE help in handling a structural fire. Used improperly, it can definitely help burn a house to the ground real fast. In fact, I would not be surprised if a fire department one day gets sued for negligence for misusing PPV and burning a house down. And for what it's worth, yes I have worked fires where PPV was mis-used and caused more harm than good. I think that usually happens in fire departments where they get their first PPV fan, are all gung-ho to use it, and haven't had the appropriate training yet to really understand it.
For anybody who's interested, here's a good article that talks about PPV in some detail:
http://www.firetactics.com/PPV-GRIMWOOD.htm
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