Anybody recommend a small type 4 fire extinguisher? I'd like a small one I can keep in the car. I have a Class BC one, but it won't put out a magnesium fire.

I couldn't find a small one, but maybe I'm not looking in the right place.

Amazon. Purple K is the only way to go, trust me I am a Fireman, works great on metal fires.

AmerexB410T, 2.5lb Purple K Chemical Class B C Fire Extinguisher
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IIRC, Purple K is one of the agents that eats aluminum. And wire insulation.

If I'm correct in that, only use it if you need it to get yourself (and/or other people) out of the car. Because once you use it inside the car, you will need to replace much of the wiring harness, plus the crankcase of the engine. And possibly the transmission as well; not sure how that would do with Purple K.

I may be thinking of a different dry-chemical extinguisher, but at least one of them did the above.

--DD

Sorry not true. Like any powered agent it is best to blow off the residue with an air hose. It’s when it comes in contact with water then left to dry which causes problems.
If water is applied after the dry chem agent make sure it’s flushed with copious amounts of water.
For electrical fires buy a Halotron fire extinguisher. I carry both in my 914.