This message is a warning originally sent from the FBI:
For those of you who like to grill it up during the summer, here’s a safety announcement you should be aware of. Please put this information out to ALL personnel. For those of you who exchange your propane tanks, this is something you definitely need to be aware of, especially in light of the recent news of ‘Meth-labs’ in our area. Meth cooks are getting propane tanks from exchanges at Wal-Mart, Kroger, etc. and emptying them of the propane. Then, they are filling them with anhydrous ammonia (which they now have a recipe for by the way). After they are finished with them, they return them to the store. They are then refilled with propane and sent back for you and me to buy. Anhydrous ammonia is very corrosive and weakens the structure of the tank. It can be very dangerous when mixed with propane and hooked up to our grills, etc. You should inspect the propane tank for any blue or greenish residue around the valve areas. If it is present, refuse to purchase that tank. Check out the National Propane Gas Association Website for more details. They also have pictures.
The NPGA has taken down this page from their site, so here’s an archived copy of that page: