Quote: (Originally Posted by
Genesis)
But - experimentally - it doesn't work that way.
...
I'm going to throw some instrumentation at this over the next week or two.
Measuring this would be interesting. I think though there are several confounding variables making it hard to directly compare surface and depth.
At the surface you (well, me) are usually futzing with gear, lines -> task loading and harder breathing. Less monitoring handsets, lower base PO2 (e.g. .5 vs. 1.2) mean less room for error, plus the assumed 'safety' of the surface from OC make the surface a really dangerous place on Rebreather.
But regardless, what you metabolize lowers the ambient PO2 at a constant rate given a constant (loop) volume, regardless of ambient pressure. Math just works that way. What you're measuring experimentally is the effect of the above factors and similar.
Brian