http://www.npga.org/i4a/pages/index.cfm?pageid=529Anhydrous Ammonia Safety Alert - National Propane Gas Association
Please click the link to find out WHY and to see the pics.
CHECK YOUR TANK!
Be safe.
XOXO
Me
Here are two paragraphs...
"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."