On Tuesday, July 04, 2000 2:23 PM, Huw Porter wrote:

> Stop me if I'm leaping to unwarranted conclusions here, but does this
imply
> elevated partial pressures of O2 less than 0.50 are considered 'safe'?

I think that 'more practical' is a better  term than 'safe' - and then
providing that it doesn't drop below, say, a PPO2 of 0.16, or more
realistically, 0.21! :-)

Just to quote PPO2 as doseage (in ATA's) - from the ANDI manual.
"0.30 - Normal saturation dive doses.  Exposures are usually 24 hours or
more.
0.35 to 0.50 - Chambers and bells - low doseage/long term - less than 24
hours.
0.50 - Maximum saturation dive dosages - Lorraine Smith effect symptoms
begin to manifest."

> In which case, how about nitrox 37 at 3 metres?
> (PPO2=0.48, PPN2=0.82)?

That's still too high for an 'indefinite' stay! :-)

(snip)

> >Best of all the equipment's cheap!  Just a piece of garden hose!  :-)

> (thinking aloud) - I've read something about freedivers developing DCS (or
> DCS-like symptoms?) following repeated deep dives just from pressurisation
> of the air in their lungs.  So surely the air in the lungs of a
> (strong-lunged) guy at the end of a garden hose at 10m is going to be
> compressed to 2 ATM?  So therefore he'd get as nitrogen-saturated as a
diver
> at the same depth? :-?

Hypothetically?  :-)

Try sucking air down a tube when you're just one-metre below the surface!
:-)

Strike