--Yes but they really aren't big enough unless you're making a poofer for a model car! :-)

The definitive answer is possibly.

As far as pressure ratings go, almost all quality fire extinguishers are aluminum catalina type cylinders, and are very strongly rated, and some are even hydrostatically tested (like welding tanks). Now, the bad part. They are extremely thin around the threads, and the thread pitch is very nonstandard. They sure look to be tapered threads, but Fire extinguishers also have a gasket. Also, I can't find any adapters for extinguisher to NPT anywhere. We had a few of them machined for us by a friend a few years ago, but they all have been used, and he was wanting a totally reasonable but expensive amount for them. (I think around 40 bucks).

If you happen to stumble across a premade adapter for these, please tell me/us.

If you're looking for a small accumulator tank, I saw a recipie online about taking a big drill bit to one of those disposable propane tanks. The idea is that the opening is designed to "regulate" flow, but if you tap it out and open to about 3/8" or so, it should flow just fine, AND you get very standard threads.

I'd recommend going here: ch3ch2ch3.tribe.net/

While there are absolutely knowledgable people here, this Tribe is populated who make propane devices their passion! Good hunting.

I've seen it done by one of the DDI folks..........real trick shit!!!