I posted the one above this just as a quick reflex [trying to be funny, did I succeed?], but now that I think it more, pieces come to their places.
Of course we have a lot of divers (up to instructors, and God knows, CDs) thinking in almighty psi. That's what the instrument is showing you, that's
where the emphasis is being put!.
Just to show you my point: what does indicate the engine oil gauge in your car?? huh?? oil's temp? pressure? volume? In most cars it doesn't even give you units, you've got a treshold in red and a red lamp, and that's all (at least in most cars I know). So the emphasis there is being put in that "red zone", and the rest is a black box for most of us (by the way, that gauge usually indicates oil's pressure).
I've seen divers that even don't have the 500psiBB rule, they're guided by the red zone in the SPG!!
So even if you mention the importance of proper air management during the OW course (and I think instructors must), odds are [most of] those people will pay more attention to what's being laid in front of their eyes as the most important fact: pressure.
If we want divers to think in terms of volume left, I see three options:
1.- You have them doing rock bottom calculations (IMHO unlikely because of the reasons I exposed in the previous post) or
2.- You standardize the volume of all tanks in the world, so pressure will become meaningful (absurd as it can get) or
3.- You move from the SPG to the SVG (Submersible Volume Gauge), something that will require not few technological (and economical!) developments.
My 0.02 cu.ft. @ 500 psi
