I ran across a story on the intranet at my office that I thought I would share with you all. It's the kind of thing that everyone could benefit from, so please share it with as many folks as possible.
Meth critters are using the exchangeable propane tanks to hold the anhydrous ammonia that they use in the manufacture of their drug of choice. They rent them, empty them and return them when they are done. The ammonia is extremely corrosive and weakens the steel in the tanks. When the tanks get refilled and the propane mixes with the left-over ammonia in the weakened tank, bad things happen.
There will be a tell-tale greenish corrosion on the valves. If use these services, please check the tanks before you tank them for that greenish corrosion and if you see it ask for another tank.
I would just use my own tank and have it refilled at a propane station.
If you'd like the read the alert from the National Propane Gas Association you can find it at the link below.