New propane tanks are easy to obtain at your local home and garden store, but they do not come ready to be filled with propane. Unless you're purchasing a used propane tank that's already full from a propane exchange, you'll need to purge the propane tank. New propane tanks contain pressurized air that needs to be purged with propane vapor before the tank can be safely filled with propane and put to use.
Connect a used but full propane tank to your new propane tank with a connecting line featuring a regulator and a bleed port with a dual-purge valve.
Slide the connecting line valve to the "purge" mark, and open the valve on your new propane tank by rotating it counterclockwise as far as it will go.
Open the valve on the used propane tank by rotating it counterclockwise as far as it will go. Slide the connecting line valve to the "charge" mark. Wait until you can no longer hear the gas traveling through the connecting line. It will take approximately one minute for the gas to flow through a 20-lb. tank.
Slide the connecting line valve on the used tank to the "purge" mark and allow the propane vapors to bleed out of your new propane tank. This will take less than one minute.
Run through the priming process four more times before using your new propane tank.