I did 23 years in the fire service, so I speak with a little experience.
A 5lb Amerex ABC extinguisher will do for most things. if you have a camper or toy hauler, then I would get a 10lb. Larger than that becomes cumbersome, and if you cant put it out with 10lbs of ABC powder, you need to get everyone away and call the fire department.
And Halon is no good for most fires in cars. Doesnt work for class A or B fires and unless you disconnect the battery first, wont work on class C fires.
Halon gas works on the principle of blocking the oxygen from feeding the fire. It doesnt remove heat like water or CO2, and it doesnt coat and block like dry powder. As soon as the halon gas is dissapated or blown away by the wind outside, the heat and burining material is free to re-ignite.
Places like computer rooms use Halon because its a closed space and when the system activates, it shuts down the HVAC system and floods the room. Same with the US Navy (who is the largest user of Halon in the world) Seal the compartment and flood it with Halon, fire goes out, and then wait till it cools down before you open the hatch.
if you have a fire in your car, the last thing you will think about is damage to your sterio. You will want to put the fire out quickly and effectively to insure it doesn't flare up again in 15 seconds when the Halon disapates.
I am a DoD District Fire Chief/EMT, with 35 years' experience and now retired, so I also have some expertise in this area. NYresQ's statement is right on the mark, and I concur completely. There are only a few things I would like to add...
1. Halon is useless fighting a vehicle fire! If you use it for a stove fire in an RV, you better have the windows and doors open, then dump it and run.
2. ABC is the extinguisher of choice for vehicles, but carry two of them (Murphy's Law), either the same size (5-10 lb.) or one smaller (2.5-5 lb.) and one larger (5-10 lb.) size. IMO, the 2.5 lb. size is almost useless, because you have no reserve capability. One shot and it's gone, so I hope the fire doesn't flare back up. If you have the room to carry only one, go with a least a 5 lb. model. Just remember how far away the closest Fire Department is when your truck catches on fire on the lonely mountain road.
3. PKP is good for vehicle fires, but it is highly corrosive when it gets wet.
4. Any kind of powder does pack down over time, especially if subjected to vibration also. Our procedure for any Dry Powder Extinguisher carried on a vehicle was, once a month we would hold the extinguisher upside down and tap the sides and bottom with a rubber mallet, starting at the neck on the cylinder (which is now upside down) and working around and up towards the bottom of the cylinder, which is now facing up. This will cause the powder to fall toward the neck and 'fluff' itself up.
5. CO2 does have a cooling effect right out of the horn, but is really only effective in an enclosed space. It dissipates almost immediately, and has no lasting effects to prevent reflash.
6. Don't forget to check the seal on your extinguisher. It holds the safety pin in place on some extinguishers, and can allow the pin to fall out if broken. Having a 10 lb. dry powder extinguisher slide forward in the trunk of 1968 Mustang and wedge in the 'open' position will ruin your day. Don't ask me how I know!
7. How many of you have Magnesium or Titanium wheels, engine blocks or manifolds, or other parts on your rigs? These combustible metals will burn with an intensity of an arc welder, and common extinguishing agents will not put them out.
The only way to extinguish a combustible metal fire involving alkali earth metals and transitional metals is to provide an inert atmosphere of argon or helium, which in most fire situations is impracticable. Applying other agents will contain the fire until the metal has oxidized to a point at which heat production is reduced below the ignition point.
Putting water on it is like putting gasoline on a campfire! For every gallon of water you apply to a combustible metal fire, there is a potential release of hydrogen equivalent in energy to 0.43 gallons of gasoline. Every 100 gallons per minute of fire flow on a combustible metal fire provides the equivalent of 43 gallons of gasoline. You are also applying a significant amount of oxygen, which is also released to assist the burning.
You can read more here:
http://www.fireengineering.com/arti...oper-handling-of-combustible-metal-fires.html
Back in the early 70's, we responded to a vehicle fire which turned out to be one of those VW dune buggies with a fiberglass body and magnesium rims, custom engine components, and even the fuel tank which looked like a beer keg. We dumped everything we had on our Fire Engine on it, and it still burned to the ground...literally. There was nothing left but the frame and a few other steel components.
Well guys, that's my story and I'm sticking to it. I hope it helps in some way.
