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James, Helium is a small molecule. It does not take much energy to heat an amount of it (relatively speaking to lets say air). Since less energy is required to change its temperature, it does not work well as an insulator. This is one reason why it should not be used in a drysuit. Another is that helium can enter the skin ( if used as a drysuit gas) and cause problems (like now a diver has MORE helium in his tissues than expected due to the pressure gradient between the suit gas and the breathing gas) This would be a good way to get skin bends (but not vestibular bends) along with a screwed up deco schedule. Breathing helium causes less heat loss than air because helium is more easily heated by the body (the body expends less energy heating the gas just inhaled). Helium is less of a thermal resevior than air is. Steve > -----Original Message----- > From: James Dibbs [mailto:JDibbs@ma*.co*.au*] > Sent: Wednesday, March 15, 2000 3:37 PM > To: 'Steve Hogan'; grnbrg@cc*.UM*.CA*; mjblackmd@ya*.co* > Cc: techdiver@aquanaut.com > Subject: RE: Helium > > > I am interested in this thread as I always thought that you > lost more body heat using helium > > "Helium is indeed more conductive than nitrogen, which is why > it should not be used as a suit gas. However, conductive > heat loss through the lungs is actually less with helium, as > the heat capacity of helium is lower than nitrogen." > > Can you tell me the relationship between Specific Heat > capacity and conductive properties? > > Looking at the above comments I don't understand why you get > more conduction using helium as a suit gas but less when you > are breathing it (granted that you would be using 100% for > the suit and a lower % as part of a breathing gas). > > Interested in your comments. > > James Dibbs > Sydney, Australia > -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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