Argon and Dry Suits -- How much warmer?

[Spimon]

Argon has a thermal conductivity of 0.01772 W/m/k and air (78% nitrogen, 20% oxygen) has a thermal conductivity of about 0.024 W/m/k.

So from a purely theoretical point of view, under the same conditions, it takes longer for the same amount of energy to be sucked out of the diver...so it should keep the diver warmer.



*Keep in mind this is based on zero real world experience. Never dived dry. No idea if the different is actually noticeable.

 

[Rick Inman]

What is preventing a group of tech minded divers (like you find on this board) from designing and conducting a "double blind"study? You would need some one with enough statistical savvy to determine the necessary number of divers, dives, and water temps to give valid results. You would probably need several LDS's to load numbered cylinders with argon or air (to help with both the necessary numbers and repeatability of the study).

What a great way to add to our knowledge.

Good idea, Dan. I'll sit on the beach with a Starbucks and you can be my ginnypig.

 

[Gene_Hobbs]

What is preventing a group of tech minded divers (like you find on this board) from designing and conducting a "double blind"study? You would need some one with enough statistical savvy to determine the necessary number of divers, dives, and water temps to give valid results. You would probably need several LDS's to load numbered cylinders with argon or air (to help with both the necessary numbers and repeatability of the study).

What a great way to add to our knowledge.

Personally, I would LOVE to see more projects like this. It is the core of Rubicon's second phase of growth (research support). We hear from people all the time with great projects they want to do. Unfortunately, so far we have only had time and resources to concentrate on the collection of existing knowledge (phase one) available since that turned out to be a bigger project than we anticipated. (But not complaining about all the cooperation we have been getting, the info just comes to us faster than we ever thought it would be <g>) So far our support of projects have been pretty limited but the first publication using some of our depth-time-temperature recorders should come out in the next year.

One of the devices we plan to pull in down the road is the "VitalSense" monitors for projects just like this and general physiologic monitoring. They are a solid unit and seem to work well when sealed in a plastic bag under a dry suit shell.

I would encourage you to read the papers and Dr. Mitchell and the UHMS diving committee's comments on the Risberg and Hope paper. Once Lew's paper is published, we will have it as well. (Papers listed in this post) If you find anything else that you don't have access to, please PM me and I'll do what I can to get it to you.

With funding for undersea research remaining where it was 30 years ago (minus the oil companies, commercial diving has tables that work for them now so no need to do anything new), majority of the established researchers retiring in the next ten to twelve years, and young researchers leaving the field regularly from the lack of funding, this type of work becomes VERY important.

I wish we were in a position to put some funding towards this but our plans for phase three of our growth (provide funding) seem to be getting farther and farther away with the economy (among other issues).

 

[ligersandtions]

What is preventing a group of tech minded divers (like you find on this board) from designing and conducting a "double blind"study? You would need some one with enough statistical savvy to determine the necessary number of divers, dives, and water temps to give valid results. You would probably need several LDS's to load numbered cylinders with argon or air (to help with both the necessary numbers and repeatability of the study).

What a great way to add to our knowledge.

I would absolutely love to see a study like this done. It would be great to know if argon truly keeps you warmer, or if it's more of a placebo, in that you expect it will keep you warmer so your brain convinces you that you are warmer. I am skeptical, so studies like this would produce results that could sway me one way or the other.

It would be interesting for someone to do their own study similar to this. Have a buddy get you two small bottles - one with argon, one with air. Have him mark them in some way so that he knows what's in there, but you don't. Make your dives and objectively make conclusions at the end. You'd probably want to repeat multiple times, at different temperatures, while keeping all other factors the same (undergarments, no leaking of your suit, depth (amount of gas in your suit), time spent at depth, etc). Right now, I just use the air from my tank for my suit, but if I ever get to this point, maybe I'll try it out and do my own experiment!

Argon has a thermal conductivity of 0.01772 W/m/k and air (78% nitrogen, 20% oxygen) has a thermal conductivity of about 0.024 W/m/k.

So from a purely theoretical point of view, under the same conditions, it takes longer for the same amount of energy to be sucked out of the diver...so it should keep the diver warmer.

From a purely theoretical standpoint, you are absolutely correct....but I'd be curious if the difference in thermal conductivity would be enough that you would actually feel a difference in warmth. I have my doubts, but wouldn't mind being proven wrong....

 

[Steve_Dives]

I saw a study where an instrumented dummy was placed in a drysuit and then immersed in cold water. For this study they purged the suit extensively with argon, but didn't really elaborate on the procedure. I recall an improvement of 10-20% was their result (going on memory). I think I found the study through DAN somehow.

Separating drysuit inflation from your breathing gas & air cell inflation for added redundancy is another benefit. And if you're doing dives that require that level of redundancy, why not use argon?

 

[b1gcountry]

6cf argon bottle $90
Catalina Pony Bottle Tanks, Yellow with K-valve

Argon Reg $150
https://www.diverightinscuba.com/catalog/product_info.php?products_id=2350


-or-

Fleece Vest $30
Columbia Men's Tall Fleece Vest from Campmor

 

[Doc Intrepid]

see Stinton (2006), page 79 in this document:

http://www.si.edu/dive/pdfs/proceedings_asdw.pdf

Basically Stinton contrasts the outcomes of Risberg & Hope (2001) with Weinberger (1989), which tended to contradict one another, and concluded that the type of drysuit used played a large role in whether argon was perceived to be beneficial or not. Risberg (the Norwegian study with the infamous rectal sensors) used neoprene drysuits - so significant insulating properties came from the suit itself. Weinberger used shell drysuits.

The "dummy" tests referred to above may have been Wattenberger (1978) using "a series of thermal manikin tests at the ARIEN Natick facility" (Stinton, 2006, page 78).

More testing undoubtedly should be performed. But "comfort" is perceived differently - anyone who has lived with a spouse knows about being entirely comfortable when s/he is too cold/hot.

Tests will need to be rigorously controlled for internal/external validity, as quantifying "how much warmer" a group of divers is using Argon will continue to be challenging. As Risberg found in his blind study; those divers who THOUGHT they were diving on Argon perceived themselves to be much warmer, when all they were actually using was air. The human mind is an amazing thing.

IMHO Argon is most useful when --
* Breathing helium mixes;
* Using a scooter;
* Performing long deco hangs;
* In very cold water;
* With at least 3 complete fills and purges of the drysuit before entering the water.

Its such a PITA to use Argon properly that only the need for significant thermal protection for the above reasons justifies the extra cost and bozonity.

When I use it under the above circumstances, we purged our suits from an aluminum 80 filled with argon. If I'm not in these conditions I tend to use "airgon" in my argon bottle!

FWIW

YMMV

Doc

 

[bleeb]

Argon has a thermal conductivity of 0.01772 W/m/k and air (78% nitrogen, 20% oxygen) has a thermal conductivity of about 0.024 W/m/k.

So from a purely theoretical point of view, under the same conditions, it takes longer for the same amount of energy to be sucked out of the diver...so it should keep the diver warmer.

From a purely theoretical standpoint, you are absolutely correct....but I'd be curious if the difference in thermal conductivity would be enough that you would actually feel a difference in warmth. I have my doubts, but wouldn't mind being proven wrong....

Not necessarily. You should also consider other major sources of heat leakage. In the insulated areas, there's also conduction through the material of the underwear. Conduction through a solid is much greater than through a gas, often more than an order of magnitude more. Also, there's the effect of moving gas, where warm gas near the skin moves the few millimeters to the cold inner surface of the suit, and vice versa. Quantitatively, possibly not so much from convection but pumping from body motion. Then there's the heat leak from the human head, the body's single largest source of heat loss, and in most cases not gas insulated.

With so many effects, it makes for a very complicated and dynamic system. Many variables can also be affected by minor changes such as how an individual diver behaves underwater. Chances are that while one factor like gas conductivity may be larger, it's unlikely to be overwhelmingly so. I would have guessed at most 10%, but:

I saw a study where an instrumented dummy was placed in a drysuit and then immersed in cold water. For this study they purged the suit extensively with argon, but didn't really elaborate on the procedure. I recall an improvement of 10-20% was their result (going on memory). I think I found the study through DAN somehow.

 

[Gene_Hobbs]

The "dummy" tests referred to above may have been Wattenberger (1978) using "a series of thermal manikin tests at the ARIEN Natick facility" (Stinton, 2006, page 78).

I am fairly certain the test referenced above was the more recent Nuckols et. al. work listed in my first post in this thread. (It was USN funded and not DAN but the prelim data was presented at the 2008 DAN Tech Conference)

For anyone wanting the Weinberger (1989) paper referenced in Bob's paper:

Proceedings of the DCIEM Diver Thermal Protection Workshop, Defence and Civil Institute of Environmental Medicine, Toronto, CA, 31 Jan-2 Feb 1989. Edited by RY Nishi, Workshop Chairmen TT Romet and JA Sterba. RRR ID: 3922

 

[Captain CaveMan]

Some really good info here. I'm in the transition of switching to argon. The only real problem for me its hard to get. I will have to drive 1hr to get argon because my LDS does not care to have it. I thought of using my welding argon for diving but its 75%argon and 25% Co2. From reading the forum Ive realized that will be a bad idea because of freezing the reg/valve.