PfcAJ
Contributor
I kinda suspect that, I just chose that depth range to be sure the diver was carrying hypoxic backgas. I know that 60m is Not being tech trained, I don't know where in that depth range it'd be smart to use a hypoxic backgas
D'oh. I forgot to take that into my calculation. So, roughly how much would that affect the weight of the backgas if the twinset was filled with 18/45 or 15/55? A twin 12x232 holds some 5500 surface liters or nearly 200 cu.ft.
You won't see me argue against that
Deeper than about 200ft/ 60m starts requiring hypoxic gases if you want to keep your po2 at 1.2 or less.
15/55 is a reasonable gas choice for dives in to 200-250’ range.
A cubic foot of air is about .08lbs. A cubic foot of helium is about .01lbs.
So in your example, you’d have 110cuft of helium weighing 1.1lbs, plus 90cuft of air (close enough for scuba math) weighing in at 7.2lbs. Total is 8lbs of back gas, vs 16lbs if it was all air.
So half the weight. That’s a big deal.