Status of "tankless" breathing system?

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Sounds like fiction to me. I think genetically engineering gills onto my back ala Seaquest would be more realistic.
 
Tassie_Rohan:
I want a box in the flow chart for a machine that extracts dissolved gold from water so I can pay for my dive trips.
I had an exam question like that last year, probably chemistry. The question was on molar calculations I think, but they gave us the amount of gold dissolved in one liter of sea water, and we had to calculate how much water needed processing to get a gram, or something like that....it was a lot though.
Problem with this device in my eyes....is what if it breaks? How many divers have never had a light, camera, or other water-proof doohickey flood? At least with the tank, unless it gets clogged, if anything fails, it fails open.
I'd imagine that the gas extracted from solution would be close to the same as atmospheric, at least proportional. Aquatic animals extract air by pumping blood against the flow of the water, the O2 crosses into the blood stream by natural diffusion, just like in our lungs, but they process a lot more water then we do air to get the needed oxygen because it exists in a lower percentage.
 
There no such thing as dissolved air.

Apart from H2O sea water contains a wide range of dissolved elements and molecules, including O2, CO2, N2, NaCl etc.

Dropping the pressure will do the same as raising the temperature: it will cause H2O (water) to go from being liquid to gas.

With the presence of water vapour bubbles some other dissolved chemical species will preferentially partition into the vapour phase if they are given the opportunity to come into contact with it. I guess oxygen and nitrogen will prefer the gas to the liquid, but the proportion of each that will partition into the water vapour will depend on pressure, temperature and fluid/gas composition.

Still, you still have a H2O (water) gas bubble, with only a small proportion of gaseous O2, N2, etc: its not air or nitrox.

These water gas bubbles will implode if the pressure is allowed to drop back to ambient. If you want to try to breath water vapour from this concentrator then go ahead - but the vapour must stay at a pressure below what you are at: hence breathing directly from this will result in sucking the air and tissue out of your lungs.

Fish get their O2 in and their CO2 out through concentration differences across a permeable membrane (osmosis): not by dropping pressure. They can do this because the O2 and CO2 do not enter a gaseous state: it stays dissolved in the water and in their blood. Getting a breathing gas suitable for a mammal out of water is completely different.

Cheers,
Rohan.
 
There is actual science behind the devices in question. The theory is sound, and it works.

That said, they have a long way to go before they can optimize it and miniturize it enough to make it practical. And there are other considerations which will need to be accounted for, such as "dead water" (water that has unusually low concentrations of dissolved air).

So at this point it's pretty premature to start making calls one way or the other, based on the few details we have at our disposal.
 

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