May want to check with welding supply places, look in the Yellow Pages under Welding Supply. Before you purchase a tank and have it shipped to you check with the welding supply places. I know where I go they will not fill tanks they have not had tested, even if I brought them in a brand new one. The way they, and many others work, you purchase a tank from them filled, then bring it back when it time for a refill, they swap out your empty for a prefilled one on hand.