STOP! Never refill 1 lb. propane bottles
Summary: The U.S. Department of Transportation, cautions the public to never refill DOT 39 cylinders, such as the 1lb. cylinders used for camping. These types of containers were not designed to withstand the stresses of emptying and refilling.
The public is cautioned to never refill DOT 39 cylinders, i.e., 1 lb., cylinders used for camping. DOT 39 cylinders, of any size, are strictly non-refillable. Hazmat incidents involving refilled DOT 39 cylinders have occurred, including one fatality.