NWG in this theory there has to be a class to get a card which produces $, also the tank needs analyzed so when PP blending it wont explode, you could switch tanks,, so need to bee camera on for liability reasons. and many more things need for this to happen.
:ssst: He said it was banked gas . . . .
For this to work, each cylinder will have to be registered with the filling station and given a unique bar code prior to the after-hour fill. The filling station will have to look up the cylinder in a database and make sure it has a valid hydro and vis and also to make sure that the after-hours filler is not asking for a cave fill. The technology is probably available but it's the Pareto Optimum (80/20 rule) problem. 80% of the fills will only require about 20% of the effort to set up but the remaining 20% of the fills will require most of the effort to get right. My guess is that the remaining 20% would be locked out from getting the after-hours filled. It's an interesting problem to work on, however.
Or, <gasp>, they could have the customer sign a statement of knowledge and responsibility that tanks filled must be within vis and hydro, before issuing the card!
I sure wish we'd hold the individual responsible for his or her own stupidity.