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?"

Comments

Not SCUBA

[Greg Wright]

"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."

Re:Not SCUBA

[FroBugg]

Actually, pure O2 at just about any pressure beyond 1 atmosphere can be toxic. It depends a little on the person.

The Navy rigs you're talking about are a form of rebreather. They take the air you breath out, remove some CO2, add O2, and give it back to you like that. You're limited in these cases by the amount of O2 you carry as well as the amount of CO2 the scrubbers in the apparatus can uptake. I think these also have trouble delivering at any significant pressure, thus the low-depth limitations.

Re:Not SCUBA

[nhunsperger]

This is completely wrong. Pure O2 is perfectly safe at 1 ata (ATmospheres Absolute). It is used in many medical circumstances (hard breathing, possible diving accidents, etc.) The air we breathe is 21% O2, so a claim that 4% more will make you high is bunk.

Pure O2 at 2 ata (aka, 33 feet under sea water) is deadly. You will enjoy convulsions until you drown. This is why when we are using special breathing gases (such as Nitrox, which has a higher percentage of oxygen), we keep the ppO2 under 1.6, which limits our maximum operating depth (MOD).

Old hat

[TheHawke]

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.

I am also a long time diver...

[MrPower]

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".