A device that lets you breathe underwater without the tanks?

[Don Burke]

An AL80 is 11.11liters, so something like 0.39ft3 so 677 cubic inches? Say you're willing to use something that's about 1/2" round by 6" cylinder -- 4.7 cubic inches. I don't do gases, but would that mean your 3000 psi AL80 fill would then need to be about 3000x677/4.7 = 432147 psi? I'd love to see the first stage to reduce it, and hauling about the 6 lbs of air in your jaw would be great exercise. Now THAT would be something to see the Tank Killer take a shot at!

You can not get there from here.

Once the gasses liquify, additional pressure does no good.

 

[gypsyjim]

I like the gills idea, seems to work alright for fish.

I think the problem with gills is they work directly into the blood stream on fish, rather than into lungs. It may actually be possible, down the road: there are a whole ton of things we take for granted now that would have got you labelled a doper back when I started this sport in late 69-70. Right now such inventions are pure pipe dreams, like Jules Vern: can you immagine somebody honestly thinking men could actually go to the bottom of the sea? Pure insanity!

 

[markfm]

You can not get there from here.

Once the gasses liquify, additional pressure does no good.

Rats, another great idea goes the way of the underwater nacho dispenser...

 

[wedivebc]

There is a device that will produce oxygen without tanks. Don't think it would be practical for underwater use but where I work we have literally hundreds of the units
http://www.therebreathersite.nl/Zuurstofrebreathers/USA/msa_chemox.htm

 

[H2Andy]

I've seen in some movies and shows (Star Wars, Pokemon) these things that the people put in their mouth and they could breathe underwater while using them. I'm thinking that they work by filtering the oxygen from the water to you. If these exist, where can I get one?

no, these devices don't exist. they are just science fiction.

that's an interesting idea to filter the oxygen from the water, but
that's impossible with the technology available today (i'm not going to
say that it's probably impossible ever ... who would have
thought we could fly to the moon?)

there are devices called rebreathers today, which use the air over and over
again, cleaning it of carbon dioxide and replenishing the oxygen in the air.
mabye you could shrink those to a smaller size than today... but still, it
wouldn't be as small as the science fiction devices you're talking about

 

[Charlie99]

"... liquified O2 and N2."


I would like to see a cryogenic dewar of any reasonable capacity that is as small as a spare air...

Yeah. I ran some ballpark numbers. You gain a fair amount on size and a lot on weight, it wouldn't be anywhere near Spare Air size.

It takes about 3.5 liters of liquid air to equal an AL80. About a 645 to 1 specific density ratio between liquid N2 and STP N2. About 800 for O2.

A 5 liter Taylor Wharton LN series dewar is about 17" high by 7.7" diameter, and only 7 pounds when empty (15.6# when full of N2), but it has way more insulation than is needed --- it has a 16 day holding time / 0.31 liters/day evap rate (about 200 liters or 7 cu ft of free gas per day).

Not enough advantage for the hassle of controlling the boil off and heating the cold gas. Guess I won't be getting a 15th patent.

Charlie

 

[Charlie99]

You can not get there from here.

Once the gasses liquify, additional pressure does no good.

It does look like you can't get there from here, but at least for the N2 fraction, additional pressure can do a little bit of good, since solid N2 is about 4 times denser than the liquid. Critical point isn't too unreasonable --- 33.5ata at -147C. The O2 expands a bit when it goes solid.

 

[markfm]

Now we could be getting somewhere! Solid air pellets -- just drop one under your tongue and suck on it, like a mint!

(Hey, for Great Lakes divers, -147C might seem reasonable

 

[Kriterian]

OK, call Q over at MI6, that technology has been around since 1965. Fits in a cigar tube.

Oh, and tell M that 003 said hello.

Thank the Queen noone left out that old bloke Q, he was building this stuff back before BC's and backplates were invented.

PS: Hey 003, it's me double-oh-crap!

 

[PRL]

hmmm...minature fusion reactor... I work for the dept. of Energy... We'll see whaqt they have to say... Sure...

Yeah, that should help you with that promotion you have been waiting for

But for real. Wouldn't a Nuclear fusion reactor be able to produce breathable gas from water? Water is two parts hydrogen and one part oxygen. Two parts hydrogen fused should produce one part helium. That should make a 50% mix HelOx. Spliting water with electrolisis won't produce enough volume, but a high power laser with the right frequency (maby ruby?) should produce enough.
Darn, where is my drawing board.

BTW if anyone sees a bright flash in the Chicago area, take cover, it's just me testing my minature Nuclear Fusion Reactor for my own underwater city.

I know, cold fusion, thats the answer. Or is that just a myth.