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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.
Yes, it will fan the flames, but flame isn't what kills people. It's the heat and especially the smoke. By the time fires reach people, they are already dead.
For a while now they've had gas engine powered fans. They open the front door, open a hole on the roof, and point the thing straight into the house. The cool air blowing in displaces the heat and smoke so the firefighters can enter and see what they are doing. Usually, the hoses are right behind them, so the fact that the hoses and people can get right into the house with the water offsets any flame fanning effects.
If tits were wings it'd be flying around.
Where have you seen this technique used? This will basically turn the house into a giant blow-torch.
That technique (Positive Pressure Ventilation) is widely used in the fire service, pretty much everywhere in the U.S. It is, as near as I can tell, pretty much ubiquitous. The training materials provided by IFSTA teach PPV, and PPV training materials and equipment are very much in demand in the fire service.
Your point about turning the home into a giant blow-torch does have some validity of course. PPV, when done wrong, CAN have negative consequences. Timing is crucial to do proper PPV. As one of the parent threads pointed out, the idea is to force the smoke and super-heated gases away, clearing a path for the fire crews to advance on the seat of the fire and extinquish it.
Another factor is where the PPV fans are placed. Firefighters are taught to always (when possible) attack a fire from the un-burnt side. What this means, is that when you "push" the fire, whether with PPV fans, or with the air pushing effect of hose-lines with fog nozzles, you push the fire back into territory it's already burned... this is part of the "locate, confine, extinguish" strategy.
If you did the opposite, attacking the fire from the already burned side, you would not want to try and use PPV, or you would indeed be helping to spread the fire into areas that were not yet damaged.
For anybody who's interested, here's a link to some more info: http://www.tempest-edge.com/ppv/
In my experience these fans are usually used to remove smoke from the house after the fire has been extinguished.
That's also a valid use of ventilation fans, although the fans used for negative / exhaust ventilation are usually smaller, electric fans, with less capacity in CFM.
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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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