Originally Posted by SumnerH
You'd think, but that's not how it works. If you have a permeable container that's pressurized with CO2, oxygen will continue to enter until the concentration of O2 inside matches that outside (even though the total pressure inside is much higher than outside).
It's called "Dalton's law" or "the law of partial pressures" if you want to google for more info. 1st semester college physics covers it.
That said, I think the oxygenation concerns are overblown simply because the level of permeability is tiny (and probably dwarfed by the exchange even at a well-sealed neck).
ok so the power is out at work and i can't get into my lab so i did a little O2 permeability calculations... without going into too much detail about the units, I got a value of .0012 grams*meters (couldn't figure out how to get rid of the last unit of meters)
This value is the accumulated amount of O2 based on 3 weeks in a typical 7-Gal HDPE bucket(highest O2 permeability. Now keep in mind this is also based on pure O2 and we know that air is only 21% O2 so I tend to agree that O2 permeability is basically BS.