What Happened to Cryogenic Scuba?

[VooDooGasMan]

Try Ebay and also vintage diving, alot of collectors have magazines, then look for vintage dive museums.

[Kevrumbo]

That was definitely an issue. The article mentions a 6-day boil off for their X5 model. The earlier article show images of filling rigs off a larger Dewar on the back of a pickup so it would not be that big a problem for a small group of divers or a charter boat to buy bulk liquid for a week or so of diving.

Given the cost and complexity of some cave and wreck projects, I can see how the cryogenic rigs could be attractive. Most anywhere on the continental US coastline would not be a problem. It would be usable for remote dive sites like the South Pacific or Indian Ocean where gas plants were not nearby.

Cryogenic applications are used overseas, but only for source supply chain & storage for non-immediate use.

The dive ops at the Truk Stop Hotel obtains condensed quantities of helium & oxygen by having more shipped in bulk by larger cryogenic liquid container pressure cylinders at the same cost versus the regular standard T-cylinder supply bottles with content in gaseous form --same wholesale cost but maybe 35% to 40% less total gaseous volume delivered. Still pricey at $2.95/cf, but not outrageously expensive for Open Circuit Trimix diving like the Blue Lagoon Dive Resort Helium retail cost of $4.50/cf.

The delivered liquid helium & oxygen is then vaporized and stored conventionally for later use blending mix in regular Scuba tanks. . .

http://www.airgas.com/documents/pdf/mcm-038.pdf

[-hh]

Given that the boiling point of oxygen is 90 Kelvin and nitrogen is 77 Kelvin, I would have thought that a cryogenic mixture of 21% oxygen and 79% nitrogen would lead to the following dive: first the oxygen boils off ...

That is an easy fix - dive two tanks, one O2 and one N2, and mix them on the fly.

It is probably also technically feasible to put both liquids into a single cryo tank and then use their differences in properties to develop the "extraction" strategy. For example, if the O2 floats on top of the N2, then one could pull liquid N2 off the bottom and pull gaseous O2 off the top to create your blend.

Of course, this is again greater complexity ... and thus, higher cost ... and this particular one could run into a tricky situation where the one gas runs out before the other - - how would you know?

I am not certain that it is possible to indefinitely store LN2 and LO2 at ambient temperatures. While this is possible at increased pressure with some gases (e.g., liquefied petroleum gas), it may not work with LN2 and LO2. If it were possible to indefinitely store LN2 and LO2 at ambient temperatures this would likely require tanks that are rated far in excess of 3000 psi and bring in the headache of new DOT approvals.

Correct. The classical liquid N2 cryo tanks that one finds in hospitals & labs typically vent their N2 slowly as a means to prevent overpressurization as well as to provide their own refridgeration to extend its useful life.

The system seems to be rapidly growing in complexity - it might just be that a rebreather is easier, cheaper, and less prone to failure.

Agreed. IMO, the system complexity & costs pretty clearly favor going to a CCR, if for no other reason than a CCR has a lot of factors, such as the "two tank source & blend" issues inherent to it as a "sunk cost", and a CCR would probably benefit from having smaller/lighter cryo supplies vs. compressed gasses. From a historical perspective, we can then look at the date of this article and see that the control systems required to make a CCR adquately safe simply didn't exist back in 1967 (let alone afforadably), so the CCR application wasn't available to them as an option, so the technology approach died as being too expensive for the benefits it could provide.

Cryogenic applications are used overseas, but only for source supply chain & storage for non-immediate use.

The dive ops at the Truk Stop Hotel obtains condensed quantities of helium & oxygen by having more shipped in bulk by larger cryogenic liquid container pressure cylinders at the same cost .... The delivered liquid helium & oxygen is then vaporized and stored conventionally for later use blending mix in regular Scuba tanks. . .

With probably the key observation being that the approach is cost-competitive.


-hh

[Akimbo]

Completely unrelated and sorry to derail, but anybody know how I could procure a copy of that article in Time magazine. Jim Woodberry was my father-in-law.

I didn’t see the article in Time Magazine but have both issues of Skin Diver. I can scan them if that helps.

Can you provide any insight as to why the cryogenic Scuba never made it to market? The Skin Diver article made it sound like it would be out before the magazine hit the news stands.

[Akimbo]

Based on both articles in Skin Diver, the problem of maintaining the mix was solved with the earliest prototype. I never understood how they solved that problem or how they made it position insensitive, especially on the final single Dewar prototype.

[Bob DBF]

Try this link. 2000-10 Time Capsules

1967 What Ever Happened to Liquid Air?

It could have been the wave of the future; the “dawn of a new era in diving.” It was lightweight, compact, carried a six- to eight-hour air supply, was easy to use, and as of the printing of this article in June 1967, seemed relatively safe. Cryogenics had been used in research laboratories, aerospace and medicine, so why not scuba? This was what prompted Jim Woodberry to invent the liquid air scuba device, which was made up of “a pair of Dewar tanks to hold and insulate the liquid air” and a system of pipes, valves, warming coils and tubing that transformed the liquid air to breathable air. The system’s estimated cost was about $300 to the diver, but dive shops would have to invest around $9,000. Was it the investment of money or imagination that put the freeze on cryogenic scuba?

And don't forget that this was 1967 money. Unfortunatly they do't go on to research and report if anyone is still tinkering around with the concept. It would seem that the infrastructure and availibility of cryogenic air is much better now, but if the cost of building the unit is too high to market end of story.

If you could find someone in the scientific community, like Thal, that was intrigued by the concept, they might do a search on the research, and who is doing it, for you.


Bob
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I may be old, but I’m not dead yet.

[Matt O'Boyle]

Hello!

I'm kind of new here, but I remember reading this article when I made my account a few days ago. I was reading some news articles today and came across this... I thought it might be something to go on.

Into the abyss: The diving suit that turns men into fish - Science - News - The Independent

Apparently, someone patented a suit in the not so distant past to do just that. Interesting read.

[Akimbo]

Liquid breathing experiments were published In Skin Diver Magazine in the mid-late 1960s. Animal studies proved it worked in a lab, but all the animals died from Pneumonia because they hadn’t figured out how to get the lungs dried out.

From a practical perspective, the biggest problem is hypothermia. We lose about 50% of our heat through respiration. That would require keeping the liquid circulated through the lung to be heated very near body temperature in addition to oxygenation and CO2 removal.

[Slamfire]

Doesn't the NASA neutral buoyancy lab store their O2 and N2 in liquid form?