Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: johndiver on 18/02/2005 13:28:01
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When we dive in cold water wearing a dry suit, we inflate the dry-suit with a little bit of air to make it more comfortable and provide some insulation from cold water. In arctic diving, sometimes argon gas is used for its superior insulation properties (as opposed to helium, which transfers too much heat from the diver to the water). Neon is not used as it causes narcosis in the diver. However, has anybody any idea why krypton is not used? I would think its insulation value is greater than argon's, but haven't found if it is a problem physiologically or if the cost of krypton is too great.
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I am intrigued that these different gases could behave so differently. As to why neon, but not helium, should cause narcosis I am unsure.
Chris
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In arctic diving, sometimes argon gas is used for its superior insulation properties (as opposed to helium, which transfers too much heat from the diver to the water).
Due to helium's relatively low molar (atomic) mass, in the gas phase its thermal conductivity, specific heat, and sound conduction velocity are all greater than for any other gas except hydrogen. For similar reasons, and also due to the small size of helium atoms, helium's diffusion rate through solids is three times that of air and around 65% that of hydrogen...Helium is less water soluble than any other gas known
http://en.wikipedia.org/wiki/Helium
That would explain why Helium is a poorer insulator than Argon, and why Helium does not cause narcosis.
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Have you seen the price of krypton?
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Yeah, you'd have to be superman to pay that much (then again he's allergic to it isn't he?!). But certainly, it's high, even by British diesel prices...!
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Incidentally, there seems to be some disagreement about neon causing narcosis. It hardly matters because it's horrribly expensive too (and no better an insulator than argon).