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Hi Bob, I worked for a fire protection equipment company in Honolulu for a short time after I got out of the Army. There isn't much to know about fire extinguishers. Kidde is a good brand. Extinguishers are rated A, B and C for the classes of fires they can deal with. A is solid combustibles, B is liquid combustibles, and C is electrical. The dry chemical powder in extinguishers is basically bicarbonate of soda with a non-caking agent. It is great for B and C fires, less good for A fires because it lacks the quenching capability or water (as in the old soda/acid extinguishers you turned upside down, then squirted on the fire.) Smaller dry chemical extinguishers are often rated only BC because they lack the volume of powder to smother a fire fed by burning solids. Larger dry chemical extinguishers got an ABC rating when they had more than a certain weight of powder---5 or 10 pounds, but I don't remember. Dry chemical extinguishers are effective but very messy. CO2 extinguishers are totally clean but won't put out a fire as reliably. Any fire fed by combustible liquids has a tendency to keep reigniting around the edges of the immediate CO2 plume unless it (the fire) is very small. I don't think CO2 is rated for solid combustibles at all because it lacks quenching capability and its smothering capability is very brief. Aside from complying with local fire department or insurance company regulations requiring certification of inspection, there is little need to pay to have dry chemical extinguishers serviced. Professional servicing consists of two easy procedures. If the extinguisher has a pop-out stem instead of a gauge, push it in. If it pops back out the unit is still charged. If it has a gauge and the needle is still in the okay zone, flick the gauge hard with your fingernail. If the needle quivers it's good. Then turn the extinguisher upside down and smack the bottom hard a couple of times with a rubber mallet or something similar. This will uncake the powder if it's caked, and you're good to go for another year. The 5 to 20 lb dry chemical extinguishers I sold and serviced could be refilled and recharged, but it wasn't cost effective (35 years ago) to hydro-test them, and I never saw it done. Guys who had been in the Navy always claimed to have used the CO2 extinguishers on their ships to cool beer. We got in lots of CO2 extinguishers which had to be discharged prior to hydrotesting, and we drank lots of beer in that shop. In my experience, CO2 worked much better to make a good beer cooling story than it did to cool beer. All the best, Stan
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