Drysuit thermal insulation gas: Ar vs SF6

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For argon to really work, you need to flush the suit with argon before diving, and get out the air. So you need to carry another tank to do the flush.
 
Sulphur Hexaflouride is a REALLY bad green house gas. As an electical engineer, we have been banned from using it in switchgear for years. As a diver who wants to care the for environment (underwater or otherwise) I think its a complete non starter.
 
Sulphur Hexaflouride is a REALLY bad green house gas. ...

Oh, what a delightful thread. It's awesome stuff.

It is the worst greenhouse gas ever evaluated.

Better still, if you pass an electrical arc through SF6, it will break down into some truly horrible things. One of these is disulfur decafluoride. DD will give up its stored energy when it finds some water, decomposing into two unpleasant acids. This could happen on your damp skin, or more typically, in your lungs.

In terms of lethality, DD is four times more toxic than the banned chemical warfare agent phosgene, so don't get SF6 near a malfunctioning can light or an electric suit heater with a short any time you happen to be diving in water, or any time you happen to be made of water, ho ho.

Perhaps best of all for divers, it is a massive but compact molecule. It has been used in hyperbaric research as a breathing medium. It gives a nice, thunderous baritone instead of the more-familiar helium squeak.

During those explorations, the researchers did not dive any extremely deep+long profiles. They felt that SF6 was safe for most uses, and uniquely exempt from being included in decompression schedules due to no perceived slow tissue compartment uptake.

Later, they realized that if they had stayed long enough at a non-trivial depth, the SF6 would have started to saturate even the slowest compartments.

When they went back to calculate the off-gassing times at each stop for those slowest tissues, they found that they had been breathing a gas that might have required months or even years to safely evacuate those compartments.

Months of decompression.

Great stuff.

You might want to stick to argon.

:rofl3:
 
Argon makes sense when you are on Trimix since you don't want the high thermal conductivity of Helium in your suit, but studies have shown it make very little difference over air. The problem is perspiration increases the thermal conductivity as the humidity in the suit approaches 100%. That problem would exist with any gas in a drysuit.
 
Argon makes sense when you are on Trimix since you don't want the high thermal conductivity of Helium in your suit, but studies have shown it make very little difference over air. The problem is perspiration increases the thermal conductivity as the humidity in the suit approaches 100%. That problem would exist with any gas in a drysuit.

Idk, 20% seems like a pretty good advantage.Thermal Characteristics of Diving Garments When Using Argon as a Suit Inflation Gas.

If you're not flushing or going pretty deep, might as well not bother though. There needs to be enough argon in the suit to make an impact.
 
Idk, 20% seems like a pretty good advantage...

The problem is it that 20% advantage is for pure dry gas, not at 95%+ humidity.

For other readers who might be interested:
Times as conductive as air
W/(m·K)
Name
1.0​
0.024​
Air (gas)
0.7​
0.016​
Argon (gas)
0.6​
0.0146​
Carbon dioxide (gas)
5.9​
0.142​
Helium (gas)
7.0​
0.168​
Hydrogen (gas)
90.8​
2.18​
Ice (0°C, 32°F)
1.0​
0.024​
Nitrogen
1.0​
0.024​
Oxygen
24.2​
0.58​
Water
Except for water and ice, these values are for super dry gas.
 
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You'd still get an advantage if humidity is held constant.

Humid argon is better than humid air.
 
I would think that if SF6 is a really bad green house gas, it is probably a really bad chemical to introduce your dry suit to. Also, I've never heard of the stuff in 30 years of scuba diving, so it must not be very easy to procure or of much use.


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