Jim, when you do an exchange on LP, the 20 lb. tanks are only filled to 15 lbs. in most cases. It used to be 17 lbs. A regular propane filler will probably fill to 20 pounds. The sticker you saw on the shutoff knob should have been removed when it was filled the first time. Any tank that is over 6 months or a year old, whatever the manufacturer indicates, should be purged even though it was vacuumed purged by the manufacturer. This is a precaution the manufacturer takes.