Why is low density important in a the dry suit insulator gas?

[David Novo]

I just started the free Science of Diving specialty that SSI is offering and one of the statements in the course materials puzzled me: "Argon’s low density and cost make it an inexpensive dry suit insulator."

I understand the negative efftects of high density of the breathing mixture, but why is low density important in a dry suit insulator gas?

 

[JohnRom]

That may be a typo. Argon has a higher density and that is why it is effective.

 

[Angelo Farina]

Argon density at 20°C, 1 bar is approximately 1.641 kg/m3, whilst air is approximately 1.2 kg/m2. So argon has higher density than air.
What matters for an insulation gas is thermal conductivity, not density.
Thermal conductivity of Argon is 0.016 W/mK, whilst thermal conductivity of air is 0.026 W/mK.

 

[Bobby]

To add to what Angelo said, the higher the conductivity of the gas the easier it will take your body heat from you. Just like using aluminum in a car radiator, instead of steel, to conduct more heat away from the engine coolant keeps the car cool. Put Helium in your suit, which is very conductive compared to Air and Argon, and you get cold very quickly.

 

[David Novo]

What matters for an insulation gas is thermal conductivity, not density.

This was my understanding and why I did not understand their statement. I will ignore the density part then.

Thank you all.

 

[Doctor Rig]

Never heard of using Argon as the dry suit gas, but it sure makes sense. How common is Argon usage and what are the recommended usage guidelines?

 

[ELCAM]

Never heard of using Argon as the dry suit gas, but it sure makes sense. How common is Argon usage and what are the recommended usage guidelines?

It’s quite common typically with a small 6cf bottle attached to your backplate. It has a small regulator with LP hose going to your drysuit and overpressure valve on one of the LP ports. To get the full benefit of the argon you have to flush the air out of your suit and replace with argon...also means that between dives you might need to keep your suit closed up to preserve the argon.
The advantage of argon over air is marginal. The main reason that argon or air is used from a 6cf is because helium is so such a good conductor and with Trimix you need a separate inflation system for your drysuit otherwise you will be very cold.

 

[Searcaigh]

I've used both air and argon and the difference wasn't noticeable. However I've used a trimix backgas once and I got cold.

Air is always available, plus if you have a whip it's easy to syphon from another tank, and it's breathable.

 

[PfcAJ]

Most dives don't really require it.

To see.a benefit over air you either need to aggressively flush the argon out of your suit or be diving quite deep so you get a high enough proportion of argon.

 

[emoreira]

As it was mentioned before, using Argon as drysuit inflation gas is almost useless if you are diving with air or nitrox, but it's very useful if you are diving with trimix, not only because trimix will chill you during the dive, but also because trimix is very expensive to be used as inflation gas.