Wow, sorry, didn't get a chance to spend any time on
yesterday. Also didn't realize there would be such interest in fire extinguisher info. Some good questions were posed, let's see if I can provide some decent answers. Is this still modified tech? If not sorry, please feel free to move it...
CO2 was mentioned a few posts back. Alot of people like myself carry a co2 tank for airing up tires. As a last resort could you use the co2 in those tanks to put out a fire. My tank is already bolted down and has a 30 ft hose that could be dragged to any part of the jeep. Just curious.
This sounds like a great idea! Here's a couple of things to consider though. If you look at any CO2 extinguisher, you'll notice they all have a hose with a "horn" at the end of them. The physics behind it go something like this. When the pressurized CO2 goes from the small diameter of the hose to the large diameter of the horn, the rapid depressurization causes an endothermic reaction. The CO2 turns into a fine "snow" and the horn lets you direct the snow at the fire. If you were to just use a standard shop blow gun to try to put out the fire, I don't think it would be too effective as you'd probably just end up with a dispersed CO2 cloud. I think an easy way to fix this would be to buy a replacement hose for a CO2 extinguisher and adapt it to a quick connect fitting so you could connect it to your on-board CO2.
One problem with this idea though is that CO2 only carries a B:C rating. Therefore I wouldn't recommend it as your
only means of extinguishing a fire. Also, to give you a rough idea of your CO2 tank's firefighting capabilities, a full 20lb tank gets a 10B:C rating and will last approximately 13 seconds when discharged at a sufficient flow rate to fight fire.
What about carrying an AFFF and a CO2 extinguisher (thinking about this in my Jeep, I currently have several cheap ones since that was what was in the budget at the time). I understand how caustic it would be, but then you would be covered for A, B, and C. I keep debating whether to go with a PKP(caustic as well does BC) and a cheapy or AFFF and CO2. I am a Vol. FF in Kodiak, when I take the Brush truck to the race track on race day I usually load it with several CO2 and an AFFF should we need it, and on big days I bring a few buckets of AFFF if something gets outta hand since I can hook up with the forestry gear and the tank. We have never had a fire on the track or in the pits so I am still interested in where I can plan ahead a bit more if you know what I mean.
Just to fill everyone else in, AFFF (A triple F) is an acronym for Aqueous Film-Forming Foam. It is a mixture of water and foam concentrate that creates a thick layer of "soap suds" when applied. It is a Class B extinguishing agent and works by creating a foam blanket over the fire which separates it from the oxygen.
This being said, it wouldn't be any more effective than plain ol' water for our purposes. It is designed for fuel/oil spills. If you were to spray it at your engine compartment, it would all just run onto the ground. It does a great job of putting out burning puddles of fuel, but it needs a perfectly level surface to form a continuous blanket on. This would be fine for you to use at the track to extinguish a fuel spill fire, but off road you're not going to find too many level surfaces to lay your foam blanket on.
Also, it gets it's A rating from the water in it. A 2.5 gallon (equivalent to 20lb) AFFF extinguisher still only gets you a 1A:30B rating. Also note there is no C rating, hitting energized equipment could be a shocking experience.
Where would one mount a larger extinguisher close enough to them to make a diff. I have a 2.5lb that was mounted in my cargo area and was told to move it up front because by the time I got to it it would likely be too late on an engine fire.
I see this recommendation often but don't really understand it. Just don't bury your extinguisher under a bunch of cargo and you'll be fine. You can't fight an engine fire while sitting in the driver's seat so mounting it up front isn't really
that beneficial. The 5-10 seconds it takes to get your extinguisher out of the cargo area (if it's kept easily accessible) is not going to make the difference between saving the day and burning your XJ to the ground.
I guess I should have prefaced my comment by saying that I am assuming that most car fires will be in the engine compartment which would tend to be electrical, gas, or oil. I have seen 3 car fires in the last 2 years (I'm sure you have seen many more), all of which started in the engine bay. In each case by the time it got to plastic, carpet, etc, the fire was well beyond what a person with a 5-lb extinguisher could have handled. At that point you step back and wait for the professionals to come put it out.
Let me clear something up before answering this question. I keep referring to B:C extinguishers as not being appropriate for our needs. Maybe I should provide a little more explanation. It's not that a B:C extinguisher won't put out an engine fire, it will... The problem is that it won't keep it out.
It knocks down the fire by either breaking the chemical chain reaction (combustion) or by occluding oxygen and smothering the fire. This is fine for a fuel, oil, or grease fire because once they are out, they are out. They don't smolder. A fire in ordinary combustibles on the other hand tends to have deep seated embers and will smolder for a long time after the active flame is extinguished.
So back to the above quote, your engine compartment contains
a lot more than just electricity, gas, and oil. Sure there's no carpet, but there's lots of rubber including hoses, belts, and plug wires, and tons of plastic of every imaginable type including wire insulation, fluid containers, fan shrouds, air boxes, and electrical components just to name a few. Oil or gas may be responsible for igniting the fire, but typically it is all the ordinary combustibles in your engine compartment that are responsible for the growth of the fire.
:flame:
So here's the scenario... a short in your wiring causes a spark to ignite some oily residue, the fire quickly spreads across the residue as the wire insulation ignites your ribbed wire loom, your intake draws the fire into your airbox and your air filter catches fire. The engine dies and you start to see smoke. You run and grab your portable B:C extinguisher and dump it's contents into your engine compartment. You knock down the flames and assess the smoking damage. A breeze blows past and suddenly some smoldering melted plastic reignites. The fire quickly grows as your B:C extinguisher neither extinguished all the embers nor provided any lasting protection against them reigniting. Your B:C extinguisher is now empty after having fought the original fire so you just stand back and watch as your beloved XJ burns to the ground...
In everyday situations, a B:C would probably be sufficient. A fire engine would be on scene within 5 minutes and could deliver massive quantities quantities of water to fully extinguish the fire you knocked down with your B:C extinguisher. Unfortunately, on the trail we are our own last resort. No fire engine to back us up. You better hope your fire is
all the way out before you run out of extinguishing agent.
