Scuba Diving With No Tank

[jaded]

but thats not the question... what is the volume of pure 0² needed for a diver to stay under water for an hour... I think a 32% mixture is pretty standard for low level diving, but if its 21% and I breath a litre of air every second or so I figure thats about 12.6 litres an hour of pure oxygen which is roughly 3.3 gallons of oxygen per hour. If it takes 500,000 gallons of seawater to produce 3 gallons of 0²... well then, this invention would kill a reef in no time at all

it just doesnt add up! I'm sure its my math, but wow

[matt]

One thing to remember is that fish, being cold blooded, probably require far less oxygen for metabolism than mammals who need to sustain a steady body temp. This is supported by the fact that warm blooded marine mammals breathe from the surface; I suspect if it were practical for warm blooded animals to extract oxygen from sea water, some would have evolved to do this.

Regarding divers' air consumption, as Jose said, it's typical to use 80 cubic feet of air in 30-60 mins depending on depth. Some divers use blends of air that contain up to 40% oxygen, but this doesn't significantly reduce consumption, it just lessens the build up of nitrogen, and diving depth is strictly limited when using these blends due to O2 toxicity. So you're talking about maybe 20 cubic ft of O2/hour with lots of variables. The biggest one is that we breathe by equalizing (actually increasing and decreasing) pressure inside our lungs with the ambient pressure. This is why a diver needs several times as much air at depth than at the surface; the air in our lungs at depth has to be higher pressure to allow our ribcage to expand under the high pressure of sea water.

[jaded]

I wonder how this new devise works then... it doesnt seem possible

even if you consider that H²O is by definition 1/3 "O", that still doesnt pass the oxygen test when you take into account N² an dall the other components of seawater. This one is beyond me! The numbers dont add up so I must ask... is it a hoax?

[Thunderkat]

Hi-tech invention that lets you breathe underwater without a scuba tank or using dissolved oxygen. :lol

Sorry, I couldn't resist. ^_^

[bprewit]

I have never been diving but I do remember taking one end of a open garden hose and jumping into a swimming pool thinking I was going to sit at the bottom and breathe through the hose. Of course it didnt work as the pressure of the water at 9' was too great for me to inhale a breath of air. When diving I know the compressed air tank has a regulator and the air is fed to the diver at a certain pressure so must you vary this pressure when diving at deeper depths? Do you need "X" amount of pressure to be able to take a breath at "X" depth? Thats off the subject here but was just curious.
If someone was to come up with a more energy efficient way of electrolysis is it possible that a miniature version of a oxygen generator on a sub could be used for diving? Of course you would need another supply of gas such as nitrogen to mix with the oxygen to make breathable air but I suppose that would be possible eh? I know at present time it takes a low voltage high current source for electrolysis but is it possible he is incorporating something simular to this in his design? Sounds more feasable than just pulling dissolved oxygen from water to create breathable air so maybe electrolysis to help create oxygen and a centrifuge to create low pressure and pull available gases from the water as well? Or maybe I have too little oxygen to my brain and im crazy!

[Someone]

I am so confused.... :wacko It seems like the idea is good... Just take air out of water because water is H2O So there obviously is O2 in water,(duh) And how to take the O2 out makes sense.... BUT what doesn't add up is all the numbers to make it work... AND if they come out with something like this, Everybody will want one because it will be so simple and safe to dive, That means there will be like a ton of ppl in the water at any given time, And although the amount of divers diving now using one of these shouldn't cause much trouble, the amount of people in their taking O2 out of the water would be to great,... And eventually it would start to kill things. JMO just look at my sig for more info...

[matt]

When diving I know the compressed air tank has a regulator and the air is fed to the diver at a certain pressure so must you vary this pressure when diving at deeper depths? Do you need "X" amount of pressure to be able to take a breath at "X" depth? Thats off the subject here but was just curious.

The way regulators work is that the 1st stage, which attaches to the tank, supplies air at an "intermediate" pressure, which is around 125psi above the ambient water pressure. So the deeper you go, the more air is delivered to the 2nd stage, which is what you breathe from. This stage supplies air to your lungs at the ambient pressure, which of course increases rapidly with depth. So, basically, you're breathing ALOT more air at depth because your lungs need more air to overcome the surrounding water pressure.

The thing is, O2 supply is almost never the limiting factor in diving time or depth; it's excess nitrogen, which is absorbed into your tissues, and eventually causes disorientation. We never experience this on land because we're breathing far less air at a given time, and our body can expel the nitrogen. At depth, though, it builds up, and pretty soon you have to surface. If you come up too fast or after being down too long, the nitrogen expands in your bloodstream quicker than you can expel it. This is the bends, and actually I've heard that whales occasionally suffer from it if they dive too deep and come up too fast, even though they're only breathing at the surface.

So, unless this system has a way of supplying oxygen to our lungs without nitrogen, I don;t see how it could expand a diver's depth or bottom time.

Edit;
I forgot a couple of things. First, there are current "rebreathers" in use which allow divers to breathe the same air over and over; it gets scrubbed of CO2 and new O2 is injected. Divers who use these love 'em. One great thing is that there are very few bubbles that come out. Anyone who's been diving knows that exhaling bubbles is fairly loud and can spook marine animals, who must have no idea what's going on... just think if you saw someone walking down the street spewing a stream of water with each breath.

The other thing is, great post Tim! I always kind of wondered about that liquid breathing thing in The Abyss.

[z28pwr]

Jaded, don't get me wrong. I believe this can be done, but I don't think it can be used on a large scale without adverse effects to the environment.

[jaded]

the only thing I can think of is that we (I) may be looking at it all wrong... perhaps the idea isnt to extract the disolverd O² but to break down the molecules in H²0 which is more than 21% even concidering that seawater isnt simply H²0

I have no idea... my head hurts!!!