Comments on: I believe Scrooge McDuck actually did it first

by: Byrn

Fri, 14 Dec 2007 03:37:33 +0000

loseweightslow,

Yep, that makes sense ;). A lungful of oxygen would sustain you longer than a lungful of air, but I think you'd still get the same desire to breathe as CO2 would accumulate as normal.

I think you're right, the PPO2 limits are based on the assumption that the person is breathing :D well done on the freediving, 25m is damn impressive.

I think I'll stick with taking air with me though... travelling 50m one one breath sounds like hard work on land to me :P

by: Daniel Rutter

Thu, 13 Dec 2007 14:22:51 +0000

It'd be pretty hilarious if that were the case. I don't think there's enough information on the Big Ox site to actually make a judgement either way.

by: pompomtom

Thu, 13 Dec 2007 13:55:43 +0000

So, is it not just water, as per the comment on the Mefi thread?

H2O molecular weight = 18.015 g/mol
O atomic weight = 16.0 g/mol
16.0/18.015 = 0.89

thus 89% pure oxygen

by: nonreality1

Thu, 13 Dec 2007 13:21:06 +0000

I'm not so concerned about the scuba diving implications in the article as I am about the fact that the Aussies aren't keeping up with the CO2 scrubbing according to the Mauna Loa Carbon Dioxide measurements.

by: Daniel Rutter

Thu, 13 Dec 2007 13:10:32 +0000

I doubt there's any "propellant" in there; a propellant is a gas added to the contents of a spraycan to make it spray. Compressed oxygen would spray just fine all by itself, so I presume the alleged 11% of non-oxygen gas in there is indeed mainly just nitrogen, with trace amounts of other random gases and non-trace amounts of the stuff that makes it smell nice.

Regarding the OKness or otherwise of scams that prey on the chronically gullible: I know what you're saying, but the basic consumer protection principle that states that goods should be fit for the purpose for which they are sold is an important one. Ludicrous audiophile products may or may not be fit for purpose - speaker cables arguably are, even when the claims made for them are extravagantly fraudulent; bullshit "quantum" doodads that don't do anything at all, however, are not.

Canned oxygen that does not actually contain enough oxygen to be useful does not, I think, pass the "fit for purpose" test.

And then, there's the issue of polluting the world with nonsense. Big Ox is hardly a major offender, but every little bit hurts. The more bullshit assails us from all directions, the harder it is to find the truth.

by: corinoco

Thu, 13 Dec 2007 12:32:00 +0000

Oh, FFS it comes in flavours. So as well as just oxygen, you get propellants and flavourings; hydrocarbons both. So it's not exactly as pure as the air on top of the EXTREME mountain on their website, unless that mountains is just outside Shanghai on a smoggy day. It would even be difficult to prove that the contents aren't just common (or garden) air, with added flavours; in fact it's just wussy air freshener or deodorant. So this 'Big Ox' group have found out how to releive ~~idiots~~ EXTREME people of their cash in a very profitable way. Good luck to them! I just wish i thought of it first. Honestly, I don't really have too much of a problem with scams like this (I'm thinking audiophiles). One of the engineers (admittedly a hydraulic engineer) I know is an audiophile who just won't take plain science as an answer, and swears by hilariously expensive speaker cables, speaker stands, shiny pebbles and 'filtering power cables'. If they won't learn, fleece 'em.

by: Changes

Thu, 13 Dec 2007 11:05:15 +0000

"Bottled water is moronic and wasteful"
I've long suspected this, and I drink practically only tapwater, but my mum and girlfriend always buy supermarket bottled water.
My dad, too, often told me I'd be feeling the difference when I got kidney stones in a few years (supposedly from the sedimentation in tapwater).
To tell the truth, my girlfriend's tapwater has small amounts of sand in it, as can be seen from the partially clogged showerhead in her bathroom, so I'm not 100% sure I can dismiss that particular claim.

Do you have any links to studies, or something, that basically state "if you buy bottled water you're throwing your money away" and/or "tapwater is just as good"?

by: loseweightslow

Thu, 13 Dec 2007 10:50:04 +0000

Byrn,
Although I didnt make it clear, my thinking was to fill up on the surface in order to extend dive time and not to use the can as a substitute scuba device.
I'm less concerned about the hyperoxia.
3.4 litres is about half my lung capacity so we can just about halve the figures you provided. I think the hyperoxia safety figure is 1.4 bar o2 but in reality, divers do the colliedge in vanuatu at 70 meters on air and many survive. (the narcosis must be disturbing though).
I have free dived to about 25 meters but my regular spots are less than 15 meters which would put the o2 level very close to the safety limit.
I think that hyperoxia is less of an issue if you are not breathing in and out the pure oxygen. Otherwise world freedive record attempts to 120 meters on normal air would cause more problems with it than they do due to an o2 bar figure of 2.1. But hyperoxia inst even a consideration for these divers.

by: Byrn

Thu, 13 Dec 2007 08:04:16 +0000

@loseweightslow That's not as good an idea as it sounds, for two somewhat related reasons. One, every metre you go underwater the pressure increases by 0.1 atmosphere (or 0.1 bar, or about 1.4psi), so lets say you freedive to 10m down, which is apparently fairly common. To fill your lungs with the same volume of air at twice the pressure takes twice the air, so the can would only be two shallow breaths, or one deep one from Dan's numbers above. More importantly, the air in the can will only take up half the volume at that pressure, so the can will be straining to implode and will quite possibly rupture (likely at the opening) before you get the chance. The second and far more dangerous reason is that oxygen is toxic. I know that sounds stupid, but above a 1.6bar partial pressure of oxygen you willd efinately get the effects of central nervous system oxygen toxicity, which is seriously bad. At the stated 89% oxygen, 1.6 would be at 1.8 bar, or 8m underwater.... If it were canned air, you'd be fine at that depth though. Byrn (certified diver ;) )

by: loseweightslow

Thu, 13 Dec 2007 07:10:44 +0000

I guess you could use one of these cans if you were free diving. I have held my breath for just over a minute in the water and if you sucked down one of these then that could extend the safety margin a bit. Of course the desire to breath is caused by the build up of CO2 in your blood and not the lack of O2 so unless you have aleady built up a good CO2 tolerance these cans will do nothing to extend your dive times. Then there is the question of where you put hte empty can when you are in the water.