SAC and Gas Consumed Calculation

Linus Torvalds torvalds at
Tue Feb 11 12:46:31 UTC 2014

On Tue, Feb 11, 2014 at 12:18 PM, Rick Walsh <rickmwalsh at> wrote:
> Also helps explain why I've found consumption, measured the
> easy/wrong/padi/my way appears better when using aluminium tanks filled to
> 200-210 bar (aka ~3000psi) as opposed to steel tanks at 230-240 bar. I
> thought it was all down to being more relaxed and breathing slower in easy
> diving conditions in warm tropical waters, where AL80s are the norm.

I'm sure it's a combination of the two. In fact, I'd expect the effect
of "easy diving in warm tropical waters" to be much more.

I certainly notice that my SAC rate in nice diving in warm waters
tends to hover around 12l, while the technical diving during my trimix
course was almost double. Oops.

> Can a statement that gas incompressibility at high pressure is considered
> when calculating gas consumption be added to the manual so other
> ill-informed divers, like me, don't get confused?

It might be a good idea. It would be possibly even better to have some
kind of "help when hovering over values" thing.

> Note that the SAC is reported differently in the info panel, as opposed to
> the dive live (when that column is added), which appears to out by the 1.013
> factor.

Ok, so it sounds like we have a real bug. Let me check that.


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