Graeme Tolton
Contributor
Sounds like this is going to continue in the accidents/incidents forum. Cylinders are not meant to be modified in any way. They are made out of one solid plate of metal. Exactly enough metal to meet requirements. Remove ANY of this metal, the tank no longer meets manufacturer's specs.. Modifying a tank OR a valve is a recipe for disaster (if you can find someone who will fill your creation). If you can't find the right valves for the tanks, cut your losses. No sense being responsible for a fill station accident over a couple hundred dollars worth of equipment.