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. This message was sent to me and I thought it should be shared. I personally do not exchange my propane tank. For those of you that do, this is something you definitely need to be aware of, especially in light of the recent news of "Meth-labs" in our area.

"There was a meth training/workshop yesterday and there was a lot of great new information presented. I wanted to let you all know about one thing that I was not aware of.
Meth cooks are getting the propane tanks from the 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). 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.

According to our presenter, you should inspect the propane tank for any blue or greenish residue around the valve areas. If it is present, refuse to purchase that one.

Pictures below.
Caution!
The brass valve in a propane cylinder will be damaged if it comes in contact with anhydrous ammonia. This deterioration will lead to cracking of the valve body or its components and can ultimately result in a violent, unexpected expulsion of the valve from the cylinder, causing personal injury or death.

Background and Recommended Action
It has come to the attention of the National Propane Gas Association that propane cylinders are being used in the manufacturing of Methamphetamines. This drug is commonly referred to as 'crank'. Manufacturers of this illegal substance are using propane cylinders for the storage and the use of anhydrous ammonia. These cylinders have been found in many states at cylinder exchange and refilling locations as well as in hotel rooms and mobile laboratories, where the manufacturing of this illegal substance takes place.

Anh Cylinder 1 - valve

As observed in the illustrations, a blue-green stain on any brass portion of a service valve is evidence that it may have been in contact with anhydrous ammonia*. The pungent odor of ammonia on or near the cylinder is also an indication. If you suspect that a propane cylinder contains or has contained anhydrous ammonia, exercise extreme caution and restrict access to the area.

It can be dangerous to move the cylinder due to the unknown integrity of the cylinder's service valve. If you determine that it must be moved, keep in mind that hazards due to valve expulsion can be reduced by pointing the end of the container in which the valve is placed away from yourself and others and towards the most safe direction.

Anh Cylinder 2 - valve & tank

Immediately contact your Fire Department, Hazardous Materials Emergency Response Unit or the nearest office of the United States Department of Justice's Drug Enforcement Administration (DEA) for information on properly disposing of the cylinder. If these respondents are not sure what to do, for assistance call 1-800-728-2482, which is the contact number for PERS, an independent hazardous materials information resource.
*Note: Sherwood valves contain a green coated valve stem. Additionally, a green thread sealing compound is used on some valves. These valves should not be confused with those that have been exposed to anhydrous ammonia.