The prototypes have all different set ups, and different dimensions. Also, Only Gravities Buffertanks are above the 1 litre mark.
But after the prototypes arrive with the tester I cant see how Im capable to keep m there.

Now, I have the tools, and the knowledge to make safe testings, and can approve prototypes.And use more than the standard procedure.
Daniel says it beautifully.
Below 1 Litre - Sound Engineering Practice applies, No CE mark required.

When going to a institute or firm that can make official pressure tests for non conform pressure vessels. ... I believe my cheapest quote ever was around the 500‚ mark, for each tank.

Now for people wanting to avoid this kind of cost. The prototype loophole I use is about the only trick in the book.Even rebuilding a CO2 storage bottle-removing the valve and placing an adaptor warrants retesting.

What Fireman Pete(and me ) did at the S7 wars. Uptubing some bottles(removing valve and bend the diptube)is also a reason for retesting.

Now the test for a conform CO2 storage vessel, with a PED licence is a lot cheaper.But not always applicable for us roboteers.