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

[Chirs]

What you have apparently neglected to consider is that the reason that "the bends" are an issue is that it is difficult to carry enough O2 to decompress on the way up.

If you had essentially unlimited O2, then you could stay deeper for longer, and do proper decompression on the way up.

As for the pressure, the air is dissolved in the water, and hence is *already* at the same pressure as the water itself. No additional pressurization necessary.

Re:Not SCUBA

[haggar]

"
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."

I am noi scuba diver, but I know a bit of physics: whatever method is used to extract the gases from the water at that depth, these gases WILL be at the pressure of the water at that depth. No need to pressurize it.

Re:Not SCUBA

[jmv]

I don't see how the contraption can both be small and deliver at a high pressure while operating off of one battery.

Because you're already at that pressure, any device will produce O2 at that pressure. It would actually be *harder* to get it atmospheric pressure.

Also, now that I think about it, I think the US navy has some pure O2 underwater low depth breathing rigs like this.

I don't think anyone uses pure O2. When going past a certain dept, I think it's mainly a O2 + Helium mix, hence divers sounding like Donard Duck.

Re:Not SCUBA

[Jherek Carnelian]

When going past a certain dept, I think it's mainly a O2 + Helium mix, hence divers sounding like Donard Duck.

Only the asian ones.

Re:Not SCUBA

[Jonathan_S]

What you have apparently neglected to consider is that the reason that "the bends" are an issue is that it is difficult to carry enough O2 to decompress on the way up.

If you had essentially unlimited O2, then you could stay deeper for longer, and do proper decompression on the way up.

As for the pressure, the air is dissolved in the water, and hence is *already* at the same pressure as the water itself. No additional pressurization necessary.

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.

It's safer if you maintain a dive profile that always allows you to return straight to the surface.

So the fact that this device could allow you to maintain at 30 or 60 feet for the 30+ minutes it might take to safely decompress on the way up isn't likely to change the rules for recreational diving.

Now it may be a big advantage for commercial or military diving where the divers are professionals and are willing and able to do dives that require mandatory decompression stops..

Re:Not SCUBA

[Jeremi]

If you had essentially unlimited O2, then you could stay deeper for longer, and do proper decompression on the way up.

Perhaps, but even with this device you would not have "essentially unlimited O2". The device requires a battery to operate, and when the battery runs out of juice, you stop getting air.

Re:Not SCUBA

[Omicron]

We (divers) do not breathe pure O2 for the working portions of our dives. We do use it during the decompression portion of our dives. Keep in mind though that recreational divers DO NOT ever use pure O2 for any part of their dive. You can get trained as a rec diver to use 40% 02 MAX, and definitely not for doing deco.

Oxygen becomes potentially toxic when the partial pressures is beyond 1.6ATA. For 100% O2, the depth limit is 20 feet. For 50%, it's 70 feet. At 32 feet on O2, you are getting very close to needing your partner pull you up and hold your regulator in your mouth until the seizures stop and you come to.

The Navy, as well as many civilians (and my friends...) have what you referred to as "low depth breathing rigs". The pure O2 ones went out of favor a LONG time ago...they were most famously used in the human-torpedoes during WWII I believe...the biggest problem with them is that as the soldiers were piloting the torpedo, they would go to deep, pass out and never return.

Today, rebreathers are used. There are both closed circuit or semi-closed circuit. They ARE NOT using pure O2. Depending on which rebreather you have, a variety of gas can be used in the breathing loop - air, nitrox or trimix. What the rebreather does is keep your breathing gas at a constant partial pressure of 1.4, thus minimizing as much as possible your inert gas loading to reduce your decompression obligation. Essentially, as you go deeper, the gas you are breathing contains less oxygen.

Re:Not SCUBA

[sirket]

Can we stop talking about "replacing Nitrogen with Helium." This is wrong for two reasons. First- it isn't completely replaced as people keep implying- Helium is added to Nitrogen and Oxygen forming Trimix. It would be hard to call it Trimix if you didn't have all three. Second- The Helium replaces the Oxygen not the damned Nitrogen. The point is to get rid of the Oxygen which becomes more and more toxic the deeper you go. Nitrogen is still there.

-sirket

Re:Not SCUBA

[MikeHunt69]

Actually, pure O2 is toxic at 1 ata (ppO2 1.0). Anything beyond somewhere around 25% O2 will give you "full body oxygen toxicity" if exposed for long enough.
Also, modern rebreathers have no problems delivering the required pressure (which is delivered at ambient). The single biggest limitation on rebreathers (after scrubber life) is the diver. Nobody wants 6+ hours in the water, where 5.5 hours is on deco.

Re:Not SCUBA

[radtea]

Some facts about SCUBA:

1) The deeper you go, the faster you use up your air. SCUBA tanks have their size given by the volume of air at one atmosphere they contain--a standard tank these days is a single 80 cu. ft. (units courtesy of the U.S. lead in dive equipment.) You breathe about 1 cu. ft/minute at one atmosphere. At 2 atmospheres (32 ft/10 m) it's twice that, and so on. With a single 80 it's a race between the no-decompression time and the air available, particularly since you've got to have enough air to decompress if you go over the limit, unless you've planned for it and put out tanks on a line at your decompression stops.

2) "Rapture of the deep" is nitrogen narcosis, which would still be an issue with this apparatus, as it will generate air, not just oxygen.

3) Pure oxygen is toxic at any pressure much above one atmosphere (there will be a movement to ban the deady gas dioxide as soon as the worldwide ban on dihydrogen oxide is fully implemented.)

The big advantage of this technology is that it makes bottom time independent of depth, which would make diving a lot safer. If you did stay down past the decompression limit, the odds are good that you'd still have battery power left to decompress.

With a tank, if you do a dive to 120 ft with a single 80, and you get nitrogen narcosis and forget to check your time often enough, it doesn't take going over the no-decompression limit by very much before you're out of air, and well and truly screwed. With this system you'd still have the better part of an hour's air left. I like it.

That said, I'm not holding my breath (as it were :-) that I'll see it on the shelves of my local dive shop any time soon. Scaling up won't be fun, nor will re-designing it for the field rather than the lab. But who knows--it could happen, and it'll be really cool if it does.

--Tom

Re:Not SCUBA

[pmc]

You can get trained as a rec diver to use 40% 02 MAX, and definitely not for doing deco.

Oh dear - I guess my BSAC advanced nitrox qualification (50% stage mix) was just a dream then. They also do an extended range course that gives 80% stage mix. Others do 100% stage mix (dunno why - risky, little extra benefit, and considerably more expensive) Just because PADI don't do it...

But other than that spot on.

Re:Not SCUBA

[Creedo]

Not exactly. I am a PADI diver(judge that as you will), but I am pretty sure that NAUI also teaches no deco diving. In PADI, all normal rec diving is considered to be no deco. We learn to deal with it if needed, but are discouraged from actually exceeding the limits. That is left for later certifications. We did a deco dive when I was taking my advanced open water course.
Now, some people have a problem with PADI's philosophy and style of teaching(I sure do), but I think their stance on no deco rec diving is fairly average for the recreational diving industry.

Re:Not SCUBA

[Deadstick]

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).

At 100 feet underwater, the pressure is 44 pounds per square inch more than at the surface (that's in seawater; 43 in fresh water). The reason for the 3000-psi tank is to get a useful amount of air into a reasonably small space; the regulator on your tank drops the pressure by 2956 psi before the air ever gets to your mouthpiece.

rj

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).

Re:Not SCUBA

[MikeHunt69]

Sorry to tell you this, but you're completely wrong. Pure O2 is not perfectly safe at 1 ata for long exposures. As I said, look up "whole body oxygen toxicity" or "Pulmonary Oxygen Toxicity". Look, Ill do it for you:

Humans can live normally for seven days with elevated oxygen levels at about half ata, although the level of hyperoxia that can be tolerated indefinitely with no pulmonary effects cannot be identified with certainty. However, exposure for 24 hours at 0.75 ata causes pulmonary symptoms in association with a significant decrease in vital capacity, and the rate of pulmonary intoxication increases progressively at higher oxygen pressures.

ok, so I was wrong about 0.25 ata, it has to be 0.5 ata minimum. If you don't know this, perhaps you should try recertification? I recommend the IANTD or TDI Advanced Nitrox course, I found them both very informative.

heh

[professorhojo]

i bet it's been tankless work. (sorry :)

Great technology!

[__aaclcg7560]

It's about time that technology is catching up with Star Wars. Now I can stay on the bottom of the swimming pool longer!

Re:Great technology!

[Rei]

While it sounds interesting, I don't think this tech is really such a good thing in the general case. Are those in charge of sensitive environmental sites where many divers go (say, reefs) going to like huge amounts of oxygen being stripped out of the water to support an additional population of large mammals and their metabolism-heavy brains? Even worse, I can just imagine how much damage a cave diver would do to the oxygen levels in some cave where water cycles slowly.

In the open ocean, they talk about using it on diesel submarines. Sounds great, unless you consider that if they can get oxygen out of the water, they may well try and power the engines underwater as well instead of running on batteries. That would strip huge amounts of oxygen from the water; it's more than a bit concerning.

I'd feel a lot more comfortable with a method like this being "backup oxygen", instead of it being primary oxygen with a small backup oxygen tank. Of course, it's probably heavy eq...

Also... wouldn't this be noisy? A high rpm motor centrifuging gas out of water, right on your back in an environment where sound conducts very well?

Great!

[pomo monster]

Now you just need some batteries: "Calculations showed that a one kilo Lithium battery can provide a diver with about one hour of diving time."

Does that make it lighter or heavier than existing oxygen tanks?

Sounds to me like a job for nuclear-powered batteries.

Re:Great!

[david.given]

Does that make it lighter or heavier than existing oxygen tanks?

Actually, weight isn't an issue --- humans float, even with heavy steel tanks strapped to them, and you need lead weights to make yourself neutrally bouyant. You can get plastic air tanks, but nobody wants them: steel is more reliable and cheaper, and having lighter tanks means you have to wear more weights. Which are uncomfortable.

Oh, and divers very rarely breathe oxygen. (Unless you're counting the weird mixtures you use for very deep diving.) It's strictly compressed air, and is usually very dry compressed air to prevent rust in the tanks --- diving is one of the few activities where you can be under ten metres of water and still have a dry throat.

Re:Great!

[climbon321]

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.

Re:Great!

[soupdevil]

I'm sure you're right -- in fact I'm having trouble thinking of ANY other activities where you can be under ten meters of water.

Re:Great!

[still cynical]

Drowning.

Re:Great!

[zippthorne]

A typical open water scuba tank (aluminum 80 ft^3) will weigh about 40 lbs (mass 18 kg) and will last a typical diver a little under hour at 30 ft. or 25 minutes at 100 ft. (assuming ideal tanks and breathing the thing down to "zero"). Since this device appears to be mostly void space (it's a turbine that will be mostly full of water during operation right?) It probably is pretty light (it does not need to be neutrally buoyant when empty: it'll fill with water at the dive site.)

Extending bottom time with a typical scuba tank involves bringing ever heavier tanks with more air. (or risky rebreathers.. they are at least as complex as this device appears to be from the article). This system appears to have some of the same advantages as a rebreather: namely that volume of gas available is not dependant on depth. This is a huge advantage for deep dives. It also seems to avoid some of the more worrying dangers of rebreather operation: there is no CO2 removing compound to react poisonously with water in the event of flooding, the O2 partial pressure is almost certainly above the minimum requirement for life (though must still be monitored). It introduces other dangers which must be evaluated: parts moving at high speed which could fail, does not have the favorable buoyancy characterists of a rebreather (each breath, buoyancy varies by the volume of O2 consumed rather than by the volume of an entire breath)

I would imagine that this would be about the same weight as a similarly capable rebreather assuming the 1kg/hour marginal weight cost. A typical laptop battery is a little under a kilogram. It would seem that the fuel-cell replacements for same would be a pretty good fit here (few moving parts, high energy density, relatively low power) Though it would add additional complexity. I'm not sure I'd want to have my primary breathing gas dependant on a battery that loses capacity as quickly as LiIon though.

Re:Great!

[DiveX]

Weight can indeed be an issue. For one thing, the term 'oxygen tank' is extremely misleading. Except for trained technical divers, SCUBA divers do not use pure oxygen underwater (yet most newspapers stupidly say the diver 'ran out of oxygen' if they refer to a fatality).

Humans will not float with steel tanks attached without some method of buoyancy compensation. Aluminum tanks are ~3 pounds negative when full and are ~3 pounds positive when empty (77.4 ft^3 [the amount of gas in an Al80 at 3000psi] weighs approx 6 pounds). A steel tank is typically negatively buoyant, even when empty. Divers need to carry weight/ballast so they can remain at their decompression/safety stop depth, even with a near empty tank, and to compensate for the positive buoyancy of exposure protection (e.g. neoprene wetsuit).

I don't think "plastic air tanks" are available. What you are most likely considering is the carbon fiber tanks that firefighters use. They need something lightweight since they are always carrying them above water. They would not be useful for underwater use since the diver would have to carry a lot of weight to overcome the positive buoyancy aspects of the tank on top of the ballast for theit exposure suits and natural buoyancy characteristics.

Oxygen is used to accelerate decompression after deep or long exposure dives. Oxygen is not taken below a depth of 20 feet (1.6 atmospheres) due to the effects of exposure. It can be managed, but just takes experience, training, and very good depth control. On deep dives, I'll normally have a scooter, 2-3 other bottles beside my backgas tanks, and will be drifting 3-60 miles away from shore without anything onto which one can hold onto for support while maintaining the exact same depth for 20-30+ minutes.

Compressed air does indeed have moisture filtered in order to avoid oxidation in the tanks. Most shops use partial pressure blending techniques to mix the Nitrox blend. Normally AVO (Aviator's oxygen) is used (instead of medical oxygen) since it is easier to obtain [some places claim some BS about needing a prescription], and because it has been ultrafiltered for moisture so it would not freeze the plumbing in planes at altitude. /technical diver //SCUBA instructor

Good News...

[Anonymous Coward]

It's a suppository.

Re:Good News...

[th1ckasabr1ck]

Professor: Oooh that reminds me: You've all taken your pressure pills, right?

Amy: Yes. STOP asking!

Oh yeah that's safe

[Rosco P. Coltrane]

ow long will it take for someone to use this to swim the English Channel underwater?

About 10 minutes, just enough time for the keel of one of the kajillion freighters that go up and down the channel to hit the guy's head...

Re:Oh yeah that's safe

[Penguinshit]

Uh, the keel would be the least of your worries.. your real cause for concern would be the big food-processors to the stern.

Backup oxygen?

[newnam]

Since this is has moving parts in it while are more than likey going to fail at some point, do you still need to carry a reserve oxygen tank? Does the device generate oxygen fast enough that if it does stop functioning, you have enough oxygen to get back to the surface?

Re:Backup oxygen?

[gregmac]

Of course, one has to wonder if said oxygen tank will allow you to properly decompress in time. Of course, when faced with running out of air, the bends may be the least of your worries.

With recreational diving, also called no-decompression diving, the idea is that you can immediately return to the surface at any point. Usually, we take a 3-5minute decompression stop at 15', just as a precaution.

To get certified (with PADI anyways) one of the things you have to do is a controlled emergency ascent (which is basically your worst-case solution if you run out of air). You actually have enough air in your lungs that on a full breath you can quickly (at the speed of bubbles) swim to the surface and you will be able to slowly exhale the whole way, since the air expands as you go. Of course, if you do this from below 60' it would probably be a good idea to go to a decompression chamber to be sure. We had to do it from 30' I think, and it was by far the least fun thing in the checkout.

TUBA?

[stagl]

Tankless Underwater Breathing Apparatus...

I think that TUBA is already taken. :)

Amazing that someone didn't think of this before

[nganju]

Usually inventions only come about when the underlying technology is improved to the point where the new invention is feasible (i.e. made possible by faster processors, stronger steel, etc).

A look at the article reveals that the main components in this invention are a centrifuge to adjust pressure, and a battery to power said centrifuge. Both of these components have been around in usable form for decades at least.

Oxygen tanks??

[Skiron]

That is a bad report.

SCUBA divers used compressed NORMAL air in the tanks. You can dive safely down to 50 metres on that (this is nothing to do with 'the narks yet').

Profession divers, usually military types (Royal navy etc.) use compressed air to deeper depths (70 metres).

The problem comes when the ratio of oxygen is greater than normal) - you can die of oxygen poisoning - hence why saturation divers have to breathe a reduced mixture of oxygen with nitrogen.

So, this is great for the pure rebreathers, but not for the common man if it do9es just extract pure oxygen from the water.

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.

Full battery charge

[jbeaupre]

I once ran out of air at 70ft because of a faulty pressure gage. And that's pretty simple technology. No big deal if you stay calm and remember your training because there is still air in the tank (gage read 500psi, pressure differential was 0, actual pressure was around 40psi).

I'm going to be a little hesitant with batteries. It's enough trouble tracking rechargable AA and laptop batteries. Now you'll need a reserve battery (for your reserve air) and it better darn well be healthy! A pressure sensor is a lot simpler than something that calculates remaining charge.

Still, I have no doubt they'll figure out how to make it robust enough for us casual divers in the next 10-20 years. 'Til then I'm going to stick with the malfunctions I know how to survive.

Who is going to use this?

[Locke2005]

This adds all sorts of new failure modes. What are the environmental temperature and pressure limitations of this gear? What are the chances of salt water leaking into the electronics? When a single failure can kill you, people tend to stick with tried-and-true technology. Anybody that relies on this gear is a fool. So while some divers might use this in addition to their conventional tanks to extend dive time, it isn't going to replace anybody's conventional scuba tanks.

how long will it take for someone to use this to..

[HotNeedleOfInquiry]

to swim the English Channel underwater?"

Probably never.

Swimming underwater will take a great deal more effort since more body frontal area is exposed to water, which is denser than air. You will also have to expend more energy to either a) stay submerged, since you would be fighting your positive buoyancy or b) dragging along more weight to stay neutral buoyant.

I hope the corporate IP lawyers take note

[symbolic]

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.

Re:I hope the corporate IP lawyers take note

[Ill_Omen]

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.
Are you sure? I wonder if on DiverDot, there aren't hoards of diving professionals complaining about how obvious this device is and how screwed up the patent system is for allowing the patent.

Re:Take your last breath and not die!

[halivar]

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.

Biology class lied!

[g0bshiTe]

His apparatus makes use of the air that is dissolved in water like the gills of a fish.

In biology class I was taught fish breathed by filtering the oxygen molecules from the water passing over their gills, absorbing the oxygen into their bloodstream.
Someone needs to tell all the biology teachers that isn't how fish breathe. Apparently they breathe by using a small centrifuge which lowers the pressure of the seawater thereby releasing the oxygen into their bloodstream. Let's not forget the internal batteries they use to power these centrifuges as well.

Seriously, this is a fascinating idea. Though as a previous poster said, I am not sure how safe it is to breathe pure O2, usually dive tanks contain compressed air, not compressed O2. Also it has little military applications as it could not be used for deep diving due to limitations of mixing the O2 with nitrogen or even helium for deep dives. This puts using it as an emergency escape method for a sub right out, unless they are above a few hundred feet. Though this really could save a ton of lives used on ships to aid in escaping lower decks, or even fighting to regain flooded compartments, or minor repairs.

Should this technology materialize I see the biggest application in the tourism industry. Think the Great Barrier Reef, or Hawaii, or the Cayman Islands. I think this would most likely replace snorkelling as a recreation at a tourist location.

Re:One kilo what?

[HermanAB]

No, no, batteries are measured in libraries of congress per kilometer.

Ah, the questions...

[BinaryLobster]

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.

Re:Ah, the questions...

[nametaken]

What happens when you hit a patch of oxygen poor water? Better have some reserve oxygen in the design just in case.

The diagram shows the diver with a pony bottle around his neck. It would be better to have one of those AND a reserve in the system itself, to compensate. I guess then you're talking more like rebreather size, though... not that little can.

Looks like your really trading an oxygen limit for a battery limit.

Yeah. I expect there is potential for battery tech to get better though. On the other hand air time is pretty tightly related to size of your gear (larger tanks, two tanks, etc). But like someone else says, you still have to worry about nitrogen buildup, etc. Does it provide the other gasses? I don't wanna breathe plain oxygen, that's for sure.

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.

Hoot! Good question.

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.

This thing is going to end up being just as big and cumbersome as a regular tank rig. Really, I think everyones better off with a rebreather if they wanna go higher tech. You're going to have to condition what you leach from the water anyways.

And what about this... it still has to make air for your buoyancy control vest. I just don't see this being as simple as the drawing. :)

Re:Ah, the questions...

[Java Ape]

Yeah - or venture into any little anoxic pockets! Seriously, many marine environments (and a few freshwater lakes) have hypersaline sinks on the sea floor.

We used to detect these while diving because you "bounce" off of the superdense water if you're neutrally bouyant, and you can see the optical distortions caused by the density difference.

These little sinks can be fun to explore, since they often have extremely well-preserved stuff in them. However, they tend to be not only anoxic, but saturated with hydrogen sulfide (which is pretty toxic) and very alkaline (which eats up things like rubber seals, exposed skin etc). Wearing this device into such an environment would be fatal.

Re:Ah, the questions...

[jemfinch]

Might not want to use this baby around any volcanic vents and such.

If you're swimming in the superheated water surrounding a volcanic vent on the ocean floor, I'd say you have more pertinent concerns than the extra sulfur your rebreather might be picking up.

Jeremy

Re:Ah, the questions...

[Frodo Crockett]

Looks like your really trading an oxygen limit for a battery limit.

Not so! You just need a really long extension cord and an AC adapter....

Patents

[kelzer]

With patents in Europe and the USA how long will it take for someone to use this to swim the English Channel underwater?"

I don't know. Probably about the same length of time it would take without the patents.

Disagree, think it could find a hold in rec diving

[SuperKendall]

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!

Re:Take your last breath and not die!

[sconeu]

You won't be able to see anything in the postcard. He's going at night, so he won't burn up!

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".

Re:I am also a long time diver...

[Java Ape]

I'm a diver too! I think you've forgotten that the gas saturation is directly related to pressure. Assuming the percent saturation remains constant, you'll have to process the same volume of seawater/breath at any depth. Generally speaking, however, oxygen saturation drops quickly below the photic zone unless there is a lot of wind/wave energy to foment mixing. So this probably is a shallow-water technology, but not for the reasons you stipulated.

Re:I am also a long time diver...

[mugnyte]

If you extract dissolved gas through a centrafuge, you're going to get all the gas in the water. This may or may not be analogous to just "air".

Secondly, by creating the gas under varying pressure, you are dealing with a complex concept:

- The mechanism creating the gas must work with (an almost static) pressurized fluid - water as input.

- After sealing and then while spinning, the gas inhabits the area nearest the axis, and floats up to the top of the chamber. The water is in a vortex. The attitude of the chamber distorts the shape of the vortex and changes the rate gas can be extracted.

- After spinning, the gas must be collected without including the water. This would then be pumped into a chamber for storage.

- Defeat the consumption of gas in the storage chamber. At depth, less gas is dissolved per unit of fluid, and this make the aparatus worker harder to keep up. Also, your "dried" water source must be flushed.

- Key to this would be a constant-fed system that kept spinning while accepting fluid and delivering gas. Side issues are the buildup of sediment (while gas is being separated, so are things heavier than water), and the seawater encapsulation issues .

- You can enter "dead zones" in open water, where the type or amount of dissolved gas is not able to support life. This would be a big danger. One's storage mechanism would need to cover for just such an emergency. Enough to surface, with decomp time if warranted.

Personally, I think they should research more into completely bypassing lungs in the system. Folks could elect for bypass surgery that installed a machine in their chests, and blood would undergo the CO2/O2 exchange in the internal machine. The machine would expose plugs to the skin, and rechargeable devices could feed the required gasses. The ingredients could be varied based on heart rate. Stopping the breathing reflex may not be possible, so a small mouth-based device might be necessary (just an unprocessed recirculation system). The volumes of gas we're talking about in this instance are much less than lung capacity. Also, compromised lung function (through smoking/pollution/defect) would not apply.

The physiological effects of the human body underpressre are numerous. Different topic entirely

Truly Vaporware

[bill_kress]

Nothing but a couple of drawings and a concept. I didn't even notice TFA discussing tests, a proof of concept would have been easy.

This is just someone looking for some venture funding. My guess is that you would have to pass a lot of water through the thing to get enough oxygen out, and between that and the batteries, you'd be much worse off than with bottles.

One of those james bond devices that pulled you along and sucked the o2 out of the water as it went through he device could work, but that is nothing like the design mentioned, and would have to contain a bigger backup tank because one cold spot and your oxygen is gone.

It could supplement subs, but if you have a sub with that much power, you might as well just blast the o2 from the hydrogen with electricity and use that, much more reliable.

Re:La Cosa Nostra

[Heisenbug]

Great, now they're going to wrap you in chickenwire, set your feet in concrete, and drop you off the pier, where you will float in murky water for days until you starve, dissolve, get eaten or die of thirst.

Have a nice day.

For all those worried about oxygen toxicity:

[geekyMD]

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...

[MrPower]

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.

Re:Rebreathers...

[tongue]

Nitrox has a higher percentage of Nitrogen, not oxygen... the point is to keep the partial pressure of oxygen at high pressures at a level that is less than toxic. to do that you have to decrease the percentage of oxygen in the mix.

Other mixes use varying levels of inert gases. according to one text i read not too long ago, the most effective to use, interestingly, was argon; i would have expected it to be either helium, as the lightest, or to increase in effectiveness with atomic weight.

good point about the ambient pressure... rebreathers have actually been used to set world record depth dives. incidentally, the guy that taught me to dive at one time had the world record for deepest non-recycled dive (meaning they were switching out tanks with special mixtures as they went down.) when you're doing dives like that (I think he got to 987 ft.) you almost literally have to invent the science as you go--there's very little published literature on what will or won't kill you at that depth.

Re:Rebreathers...

[Anonymous Coward]

The usage of "Nitrox" for sport diving is oxygen RICH mixtures, generally 32% or 38% O2 for recreational diving. The advantage is less nitrogen absorption, therefore longer no-decompression times. As others have pointed out, the disadvantage is depth limitations due to oxygen toxicity. A partial pressure of 1.4 atm O2 is the general "do not exceed" limit.

I am nitrox certified and experienced in making, testing, and using my own mixes.

A closed circuit rebreather that I have been trained on (by an ex Navy SEAL) maintains an oxygen partial pressure of 1.2 atm. The practical limit on dive time with that particular rig is cold or boredom.

Raising the % of Nitrogen (and therefore the partial pressure at depth would be insane, as you'd get a double whammy of increased nitrogen absorption causing both shorter bottom times / greater decompression requirements, and increased likelyhood of nitrogen narcosis. That is why mixes used for sustained dives below ~150 ft. use Helium, Argon, or other gases for the "bulk" in place of Nitrogen. These have other, different side effects that have to be dealt with. "Mixed Gas Diving" if I recall the title correctly is an excellent book on the topic.

Won't work..It's all about pressure.

[Anonymous Coward]

I'm very sceptical that this device will be much use . One of the primary reasons for breathing compressed air is so you can actually take a breath at depth.

You increase the ambient pressure one atmosphere (14.7 psi) every 33 feet in salt water (34 fresh water). This extra pressure makes expanding your chest cavity to take a breath very difficult without a high pressure source to breath off of. The whole reason for the first stage of any regulator is to match plus 1 or 2 psi the ambient pressure to compensate for the squeezing pressure on your chest.

At anything below 33 feet your going to expend most if not all of your energy just trying to take a breath.

Should This Get A Patent?

[ObsessiveMathsFreak]

I know that this is exactly the type of thing the patent system was designed for, and that this guy should get his patents at the drop of a hat.

But having listened to the amount for rubbish software patents and the arguments against them, I found myself thinking, on first reading the article, that he shouldn't get a patent, because it will be abused. He'll monopolise, it's not really innovative(fish do ity), he'll over price the technology, stifle innovation, etc, etc....

Wow. Software patents have really twisted my view of the whole patent system.

Think Simpler

[Effugas]

Forget about deep dives -- this could potentially be _very_ cool for diving approximately five to fifteen feet. Just being able to jaunt around a pool, or explore shallow water coral reefs, without having to maintain scuba gear would be rather cool. I imagine a snorkel that doesn't actually need to reach air.

If it was stable enough, it could even be useful for life preservers.

Units of pressure

[ari_j]

Hell, I don't care how many ATMs of pressure there are on me, it's still not going to be a fun experience. Even one small ATM would hurt.

Re:Not old hat, RTFA

[Anonymous Coward]

The parakeet thingy was demonstrating passive diffusion. This isn't the same.

If you RTFA you'll see that his technique is active. The gas is physically extracted from the sea water using a centrifigul pump to lower the pressure and let the gas bubble out like foam from a coke.

It's quite clever really.

No kidding

[kitzilla]

> 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.

I'm also a longtime diver, and the article struck me as silly.

As you note, nitrogen saturation is our primary limitation at depth. There's Nitrox and Trimix, but exotic gasses are only so useful. This proposed breathing system seems to be proposing a high-oxygen mixture. Oxygen becomes toxic at high doeses. Fabulous.

My favorite part, though, is the claim that tanks become "unbalanced" as they empty. I've never noticed this effect.

Re:No kidding

[BCW2]

Having dived since '73, I agree with most of what you said. However when tanks get empty they are lighter than when full. Weigh yours empty then full. That was never a big problem with the old steel tanks but with the advent of aluminium tanks the weight change was noticeable, that is why the bouyancy compensator was invented. With steel you went down about 2 LBS. heavy and were neutral to positive when it was time to go up. I still have my original U.S. Divers 72 Aluminum tank. It has about a 6 LB. difference full to empty. That is a bit much to deal with without a BC. The BC works just like the trim tanks on a sub. Instead of adding or subtracting water, you do it with air to maintain neutral bouyancy. That way you don't waste energy trying to maintain depth, which burns up the air supply faster.

Re:Disagree, think it could find a hold in rec div

[bill_mcgonigle]

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!

Newbies can get in a bind pretty easily too. I had a regulator malfunction at about 80 feet diving a wreck. It spewed air, which wasn't so bad for breathing (I've had them ice, which is much worse), but by time I did my ascent and was able to turn off my tank it was pretty much empty. The boat was a good 1/8 mile away and there were 7 foot seas. Yay. The divemaster was already around the ship so he didn't notice (perhaps he should have).

Fortunately I had grown up spending my summers in the ocean and had trained as a Boy Scout lifeguard (3 2-mile swims a day) and was trained to dive by a mean old Libertarian from Vermont so I was able to get back to the boat without air (it's a bitch swimming on the surface in full dive gear). But I can easily imagine less fortunate outcomes with your average cruise-ship certified diver.

Having an essentially limitless supply of air would let him hang neutrally boyant just below the surf for a very long time, at least long enough for a divemaster to figure out where his diver went to. I don't have my charts handy but he could probably hang something like a couple hours without too much risk of pressure sickness. Heck, if were small enough might as well carry one as a backup on SCUBA dives.

Re:Yeah, right

[SEWilco]

Jedi knights build their own lightsabers. We know why you don't have one.