This is what I found out, went back the drive shop to get it re-filled. The employee put 5# of CO2 into my 2.5# tank; I just needed the little one topped off for the holiday to travel with. So they gave me back my money from the other day. Then I went to Praxair, to do an exchange, the shop manager was the one that was helping me. I told him the story and this is what he told me, if tanks get over filled as the cool down to room temp they will blow out the rings inside the overflow valve. So I did an exchange for it.