Argon use with Drysuits

Well, Mr Maiken needs to spend more time with biologists and less time with physicists

I can't fault the math, but when it comes to conclusions, he says benefit is probably "in the 10-20% range". That size effect is usually undetectable in real world biology (while being dramatically obvious in physics and chemistry), and is often within the error of measurement. Say your core temperature drops by 2 degrees per hour using air as an inflation gas, then a simplistic first approximate guess would suggest that your core temperature would drop by 1.6-1.8 degrees per hour using argon, if the benefit is "10-20%". That's a small enough difference that it would be hard to measure in a real world environment. Without a measurable benefit, the cost/benefit relationship gets a little bit unfavourable for argon...

-Craig

I agree with what you said and the human body cannot really detect small temperature differences. When diving in artic conditions or for extended times, I think it would make a difference. What interests me is that someone (likely smarter than me) is telling me there is no real difference. I'm going to check out the study, perhaps my understanding is wrong. Regardless as soon as it hits my inbox I'll read through it and summarize it for the benefit of all.

Aaron

I posted the summary of the Norwegian article on the ba_diving yahoogroup which is heavily populated with tech divers. One of them posted a response in favor of Ar. I find it not very convincing and certainly not applicable to diving I do.

http://groups.yahoo.com/group/ba_diving/message/20643

The only "study" that matters is your own. If it makes you feel warmer than it's a miracle gas. Typically those who say there's no difference are those who are not using it. You get similar responses about dry gloves from people who dive with wet gloves.

I've been using argon for years here in the northwest, where the average water temperature is in the low 50s in summer and mid to high 40's in winter. The inside of your drysuit is anywhere from 60-65 degress, so a 10% improvement will give you 65-70 degress. The difference is easily noticible in these conditions. Perhaps in warmer drysuit climates where the water is already in the mid-60's it's less noticible, but up here where there's a 45-50 degree difference in water temp and body temp there's no question about its effectiveness. I've also been on charter boats up in BC that offer argon rentals and have never seen anyone give it back saying they couldn't tell the difference.

No studies, no blind tests, just real data from real users.

I will confess, when I posted this query here, I hoped the diversity of wetpixel would come through for me.

Lots of data. Well, it might not all be data, but enough informed information from folks that take their diving as seriously as I do, IMHO, constitutes data.

I feel much more informed now, and therefore able to make a better decision as to whether or not to spend the Scuba Bucks involved with a move to Argon.

Gotta love the internet!

The vast majority of users I personally know who use Argon ONLY do so when they are diving a back gas with He in it, and they do so because when using a Helium mix to inflate their drysuits, they can feel a significant difference. From what I've gathered, the difference between Air and Argon is much less noticeable, but as quite a few people said already, if it works for you, do it.

One might look at it this way...

Is it worth have a competely separate inflation system for your drysuit, regardless of what gas is used? If you're diving a single tank (not manifolded doubles), there might be some safety benefit of having a separate inflation system in case something happens to your primary reg. Of course at that point, you'd better have a backup air source as well...

Just a thought...

Tom

Thermal comfort was not different between the groups. Replacing air with argon neither improves subjective impression of thermal comfort nor attenuates core or skin cooling during cold water diving to 10 meters of sea water for 60 min.

This is the conclusion from the study that Craig cited. It also concluded that the air divers had to pee less (significant at the p= .05 level). It is important to note that the divers were blind to the gas used. The data were probably better than 20% in terms of temperature measurements meaning that the in the real world there were not even the theoretical benefits. I think we need to think of the kinetics of the system here. Even if the specfic heat of the argon were really low, eventually the system will reach equilibrium i.e. the divers will get cold. I think the 20% benefit might be important only for a short time. I have ordered the full article from the library, I particularly want to see if the "rate of cooling" was different for the two gases, I suspect it might be.

Bill

Why did the air divers pee less? I didn't get that bit, given that core temps were the same.

You guys should move somewhere warmer so you wouldn't have to worry about diving with drysuits and rectal thermometers and all that.

Alas, the problem of working for a film studio. You are limited to the Hollywood area!

I know this topic has been well covered but I have some personal observations on argon. First off I live in Akron, Ohio and most of my diving has been in the Great Lakes in the 100 to 200 foot range. At those depth the temperature in May temperatures are 40 to 45 degrees F. Late August through September you may get 45 to 48. Above 50 feet in August you can get temps in the 70s. That is tough to decide on thermal protection for a 25 degree temp swing. Dry suits are a must and argon helps a lot in my opinion. The problem is when you are spending 20 minutes or more doing deco stops in 70 degree water you get warm. What I do is have a spare inflator hose on my back gas and when I get warm i vent the Argon and replace with Air or Trimix. It is like turning on the Air conditioning so personal observation says argon does keep you warmer. Even if it is only percieved warmth.

Whichever gas you choose will heat up to some degree in the drysuit. So venting and replacing with fresh gas of any sort (which will also cool as it is decompressed from the tank, if my memory of chemistry is correct) should cool down the user, shouldn't it?

I did I medline search on drysuits and didn't come up with any other particularly useful studies (although there was an interesting forensic case of diver found with dive knife in chest...but I digress)

The study we've been talking about here was only on a very small number of divers (6 or something like that). Hey, we can get six wetpixel drysuit divers together and gather some more data. There will be a small amount of core temperature monitoring involved...but I'm sure it will be fun. I'd dive myself, but unfortunately I don't own a drysuit...

I finally got the articles sent up from the medical school! Quite interesting

Thoughts and summary from the article:

Small group of divers 6 males mean age 26

Double blind study (neither diver nor administer knew which gas was used)

Inflation gas evacuated and purged 3 times

Procedure of evacuation verified with an O2 sensor indication 0% O2 after second purging

6 skin temperature sensors and 1 rectal sensor were employed

Mean water temperature was rather cold at 2 Celsius or 36 Fahrenheit

Urinary output was 48% larger on Argon

subjectively no diver considered one dive warmer than the next

"Temperature loss was not statistically different comparing air and argon measurements."

Length of time between when divers reported being somewhat cold was not statistically different.

Some of this may be do the low sample size Type II error.

Discussion of using an argon welding gas containing CO2 which forms carbonic acid creating a burning sensation or warming effect through skin irritation.

Possibility that large amount of heat loss occurred in hands (wet gloves) and face contributed to seen data.

It seems to me that the study really does prove that in a diving scenario argon shows no perceivable difference. The perceived difference maybe psychosomatic.