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At 11:52 AM 6/16/95, Chris Elmore wrote:
> I don't know a specific formula (formulae for those across
>the pond) but my handy Physiology of Flight manual indicates a
>standard sea level pressure of 29.92 inches of mercury (14.69psi)
>and 2000' is 27.82 in Hg. (13.66psi).
>Hope this helps.
Thanks Chris. To use this, I took the percentage difference between
2000' asl and mean sea level (.07 or 7%) and adjusted the volume
of my tank by that amount (sherwood 120 @ 3500psi, 120 cf + 7%
= 128.4 cf @ 2000'). Then I divided 128.4 by 35 to get the cf/100psi.
(3.66 cf/100psi). Then I timed myself breathing 100psi of gas (EAN32
left over from my last dive) at 1900' (14 minutes). I came up with
.262 (.27) cf/minute @ sea level.
I ran the same test again, this time using my wife, and she measured
.13 cf/minute @ sea level (took her 29 minutes to use 100 psi of gas).
According to Gilliam ('Deep Diving' pp 140, 1995), the expected range
of RMV is between .3 and 3.0 cf/minute @ sea level. This puts me at
the bottom of his range, and puts my wife at less than half of the bottom
of the range. For the record, I'm 6'2" 220lbs, my wife is 5'5" 125lbs.
The thing that worries me is that I only know one diver that uses more
gas than I do on a normal dive; ie, I'm a known gas hog. Should I suspect
my equipment (SPG), my method, or Gilliam's numbers? I expect most of
the other divers here have run this test on themselves. How do you compare
with Gilliam's 'typical' range of resting gas consumption?
Thanks,
Scott.
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