Slashdot Mirror
Breathe Under Water Without Oxygen Tanks
Charlie Paglee writes "An Israeli inventor has developed a way for divers to breathe underwater without cumbersome oxygen tanks. His apparatus makes use of the air that is dissolved in water like the gills of a fish. With patents in Europe and the USA how long will it take for someone to use this to swim the English Channel underwater?"
"There are a number of limitations to the existing oxygen tank underwater breathing method. The first is the amount of time a diver can stay underwater, which is the result of the oxygen tank capacity."
I have scuba dived since 1982 and I am rarely limited by the amount of O2 I have handy. The limiting factor for any diving to any real depth (>30 feet say) is the amount of residual nitrogen in your blood stream. If that gets too high, and you surface, you get what is commonly referred to as the 'bends'; little bubbles of nitrogen bubbling out of your blood stream. Bad news. This is true for recreational diving anyway. The military, deep sea welders and others with decompression chambers might not have this problem.
The other big drawback I see is that at depth the pressure of the water on your body is very great. That is why modern scuba uses pressure delivery systems. That is, they deliver air at a pressure that is near to the surrounding pressure. This makes it so you can actually draw in a breath of air given all the pressure on your chest (and hence the 3000 psi scuba tanks). I don't see how the contraption can both be small and deliver at a high pressure while operating off of one battery. Even at ~32 feet you are at 1 atmosphere extra pressure.
Now, it may very well be great for submarines, but I don't think it will be useful for scuba.
Also, now that I think about it, I think the US navy has some pure O2 underwater low depth breathing rigs like this. The big advantage of those is that they produce no bubbles. Very stealthy.
Pure O2 is poisonous below about 32feet, if I remember correctly and if you go below about 100feet, just depending you can get high. Go google, "rapture of the deep."
--greg Vulcan quiescent... Q: What machine shutdown with this message?
i bet it's been tankless work. (sorry :)
It's a suppository.
Tankless Underwater Breathing Apparatus...
:)
I think that TUBA is already taken.
R.I.P.
We had gas diffusion processes working since the 1960s with GE putting a parakeet into a box, then putting the box into a freshwater aquarium.. The 'keet breathed air being passed to it via a 6"x6" piece of membrane.
Now the problem was the rate of diffusion, how much gas will the membrane allows to pass within a given time. The demo GE put on was fine and dandy since the bird's O2 demands were so low. But with a living, breathing, working mammal, thats a whole different kettle of fish.
I hope that the Israeli understands that before he scales up, or he might wind up agianst a dead end with the project.
First rule of holes; When in one, stop digging.
This is an invention. It is innovative, it solves a real problem, provides real value, and prior to this, did not exist. This is the kind of work that deserves patent protection. When I compare this to say, the genius behind Amazon's "one-click" patent, I find it quite humorous. There's NO COMPARISON.
You won't just be able to breath underwater--you'll take pleasure trips on the surface of the sun.
Sounds fun. Send me a postcard.
Put it on the list of technologies being limited by the fact that advnaces in batteries aren't occuring as fast as the technology relying on them.
What happens when you hit a patch of oxygen poor water? Better have some reserve oxygen in the design just in case.
Looks like your really trading an oxygen limit for a battery limit.
A centrifuge. Ah, wonder what the trade off is between swimming with a heavy tank and swimming with a spinning mass are like. Hope the moment of inertia isn't too big.
Wonder what other gasses you'll be collecting from the ocean along with your oxygen. Might not want to use this baby around any volcanic vents and such.
Except that recreational SCUBA diving, like the grandparent post is referring to, is designed to avoid a decompression stage; both because it is an easy thing for recreational divers to forget to do / skimp on, and because it affects the ability to deal with any emergencies that might arise while underwater.
While that is true I still think it will find purchase in recreational diving.
The concern about casual divers running out of air is a big part of choosing a no-decomp dive for everyone, and for semi-advanced groups you could arrange a nice dive that went deeper for a while, then shallower for a while, until they could go back up.
Another major benefit is no more problems with heavy breathers which can terminate a dive early and really throw off plans of a dive group, which is another reason I think it will be quickly adopted even if it's not used for longer dives. It finally lets people dive as long as they are supposed to without tank capacity being a limit.
And yes, on some of my first dives I was one of those people that chewed through air way too quickly. It came from trying to also do underwater photography right off the bat before I was comfortable with boyancy and as a result I used a lot of energy (and thus air) maintaining depth. I don't make that mistake anymore!
"There is more worth loving than we have strength to love." - Brian Jay Stanley
I have scuba dived since 1982 and I am rarely limited by the amount of O2 I have handy.
Because I like decompression diving, air supply is still the number one limiting factor to my dives. I still don't think this will be useful.
That is why modern scuba uses pressure delivery systems... I don't see how the contraption can both be small and deliver at a high pressure while operating off of one battery. Even at ~32 feet you are at 1 atmosphere extra pressure.
I call bullshit! First, pressure delivery systems are a direct consequence of storing air under pressure na d the reason why that is done is the convenience of have all that air in an itsy bitsy bottle! Second, the contraption will automatically create air at ambient pressure (which is all you need to be able to breathe). Third, at 10m (~33 ft) you are at 2ATM pressure, not 1ATM!
The main reason this is useless is due to the following calculation... At the surface, 1 ATM, to fill one one shallow breath (~3 litres) you would need to process 5 / 0.015 = 200 litres of seawater. Take that down to 20m (66ft - 3 ATM) and that becomes 600 litres, because the gas compresses under the pressure of the water. Now consider that a relatively fit adult might have as many as 15 of these breaths a minute! - 9000 litres a minute of seawater!Do a relatively technical dive down to 50m (6ATM) and I reckon the guy using that kit would be picking his buddy out of the water inlet!
Additionally,
Pure O2 is poisonous below about 32feet, if I remember correctly and if you go below about 100feet, just depending you can get high. Go google, "rapture of the deep."
1) This system extracts AIR, not oxygen. 2) Oxygen has little to do with nitrogen narcosis, aka "rapture of the deep".
You don't really have to worry about the divers breathing pure oxygen. They won't be. They'll be breating a mix similar to air.
The process of lowering the pressure around the seawater will lead to the release of all disolved gasses, not just oxygen. I didn't notice anything about a co2 scrubber, so I think its safe to say that the inhaled gasses will be similar in content to whatever is disolved in the ocean.
At atmospheric level, air is: ~73% nitrogen, ~23% oxygen, ~2% carbon dioxide, ~2% other, if I recall correctly, and I don't think that the solubility constants are signifigantly different in salt water to throw off those percentages that much. If anything its probably less rich in oxygen and more carbon dioxide enriched at greater depths due to marine life respiration.
With a system like this, it might even be possible to remove some of the nitrogen from the breathing mix with a second step. This would allow unlimited dive times without the nitrogen buildup that results in the bends if you stay down too long.
Rebreathers have essentially three parts.
1) The gas store/s. This is the bottles of gas used to top up the system as the oxygen levels become depleted. This gas can be air, pure oxygen, nitrox (basically air with a larger percentage of oxygen added to it), trimix (a specialised mixture of nitrogen, oxygen and helium) or heliox (oxygen/heium mixture).
2) The scrubber. This canister is scrubs out any carbon dioxide exhaled by the diver.
2) The airbag (sometime refered to as a lung). This stores the air being scrubbed in a bag at ambient pressure, which is all that is required to be able to physically breathe. As the diver descends, the air in the airbag compresses and gets topped up from the gas bottles. As the dive surfaces, the air expands and an over inflation valve releases the excess gas.
As always it is way more complicated than what I described, depending on whether you are talking closed circuit or semi-closed circuit kit - but that is the basics.
Oh yeah,
I think these also have trouble delivering at any significant pressure, thus the low-depth limitations.
Not quite - as I mentioned the gas in the air bladder is at ambient - what limits depth with semi-closed circuit rebreathers (which are far more prevalent) is that the oxygen content is usually much higher than normal air. Oxygen becomes significantly toxic at a partial pressure of 1.6 ATM, which occurs at ~ 66m (220ft) breathing air or just 6m (20ft) with pure oxygen.