Monday, March 28, 2011

Wet Stuff On The Red Stuff No Longer?

While wasting time I found a very interesting article on firefighting on Fire Rescue 1's website.

Firefighters know that in a structure fire there are other things that damage property besides fire. Smoke gets everywhere and causes almost everything with which it comes in contact to be ruined. Then there's the knuckle dragging hose jockeys. We break down doors, cut off security bars, rip out cabinets, cut holes in the roof, tear out dry wall....basically we make a giant mess. Then there's what we use to put out the fire.

I'm sure most of you have seen what happens when you spill a glass of water on a book. We do that writ large. Another issue with water is the sheer weight of it.

Temperature
- t -
(oF)
Density
- ρ -
(slugs/ft3)
Specific Weight
- γ -
(lb/ft3) (lb/US gallon)
32 1.940 62.42 8.3436
40 1.940 62.43 8.3451
50 1.940 62.41 8.3430
60 1.938 62.37 8.3378
70 1.936 62.30 8.3290
80 1.934 62.22 8.3176
90 1.931 62.11 8.3077
100 1.927 62 8.2877
120 1.918 61.71 8.2498
140 1.908 61.38 8.2048
160 1.896 61 8.1537
180 1.883 60.58 8.0969
200 1.869 60.12 8.0351
212 1.860 59.83 7.9957


So it weighs roughly 8 1/3 pounds. At my department we flow 150 gallons per minute onto a fire. That's 1250 pounds a minute of water (if we only have 1 hose line flowing) going into your house or office. That's a lot of destruction.

In the fire service our mandate is to preserve life AND property. That's why we fight structure fires. To limit the damage caused by fire, we put it out. To limit the damage done by smoke (and to help with fire suppression) we ventilate the structure. As far as the damage we cause we only do what we have to, to stop the fire and to make conditions safe. We are actually quite good at limiting the damage that we do have to cause. Up until now all we could do to reduce the damage done by water is to use less of it. That may be about to change.

At a meeting of the American Chemical Society, in Anaheim, a new way to fight fires was demonstrated. Magnetism. They focused a magnetic beam onto a fire and extinguished it. Ludovico Cademartiri, a Harvard physicist, says that they aren't sure exactly how it works but "it appears that carbon particles, or soot, generated in the flame are key for its response to electric fields. Soot particles can easily become charged. The charged particles respond to the electric field, affecting the stability of flames."

Looks like scientists have figured out how to stop the continuous chain reaction part of the fire tetrahedron. Sounds promising. It would be nice to have yet another tool in our arsenal.


1 comment:

  1. Halon was the last miracle. That didn't work out, but you never know. Can you imagine driving around a large MRI machine to fight fires while doing MRI's between calls? Watch out for the dinnerware!
    History is FULL of "They could never replace us"

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