The explanation I got on the inspections was that was the reason for the 99 year lease (or whatever it is). They still "own" the bottle and test it every so often -- part of the reason that they swap the bottle instead of refilling yours and giving it back to you. They said that if you "owned" the bottle then you would be responsible for the testing.

In any case, the lease works well for me. It doesn't matter if I am back to fill it up every other week or once every two years. Just pay the fee to have it filled and don't have to worry about it.

Not to hijack, but has anyone else looked into the DVI?