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From: Steve Hogan <Steve.Hogan@tr*.co*>
To: atikkan@ya*.co*, techdiver@aquanaut.com
Subject: RE: Helium
Date: Mon, 20 Mar 2000 09:25:55 -0800
Esat,

I did not make up anything on physiology or physics.
N2 IS narcotic and there IS an anesthetic effect... period.

Try doing your own reading (and diving)
to confirm. I do not have the references here 
but when I find some time I am sure I will find them
(or someone else will do me the favor).

Steve

> -----Original Message-----
> From: Esat Atikkan [mailto:atikkan@ya*.co*]
> Sent: Thursday, March 16, 2000 8:39 PM
> To: techdiver@aquanaut.com
> Subject: RE: Helium
> 
> 
> Oh boy someone reinventing physiol & physics again.
> 
> Anesthetic effect of N2 inhibiting 'feeling cold'. 
> Huh!
> Suggest U read a bit about heat conduction before
> pontificating w/ gradoise ideas.  
> 
> Simple - put your hand on a piece of metal @ rm temp. 
> How does it feel?  Cold - voila a concept xplained. 
> Apply that to HeOx, w/ its rapidly diffusing (read
> heat conducting) component & that is why breathing
> HeOx feels colder though net respiratory heat loss is
> actually < relative to air or nitrox breathing
> Safe bubbles
> Esat Atikkan
>  
> --- Steve Hogan <Steve.Hogan@tr*.co*> wrote:
> > 
> > You guys should try diving the stuff instead
> > offering up opinion 
> > without experience.
> > 
> > The fallacy is that helium makes one lose heat is
> > just that, a fallacy.
> > 
> > The reference is that most people go from diving air
> >  (or NTX) 
> > with its inherent narcotic (and anesthetic)
> > properties and are lulled
> > into thinking that helium makes them feel colder.
> > What is really happening 
> > is with the air and NTX dives, the anesthetic effect
> > of the nitrogen masks the 
> > cold feeling that people diving with a decent amount
> > of helium will 
> > "sense". They are no colder, just able to sense more
> > because those 
> > diving with helium are more alert.
> > 
> > Try a dive using a NTX (or air) mix first, then do
> > the same dive again 
> > using mix. Use the proper thermal protection (none
> > of this wetsuit stuff
> > so one gets chilled and artificailly throws off the
> > results)
> > 
> > Then try it again in the other order.
> > 
> > Steve
> > 
> > > -----Original Message-----
> > > From: Brian Greenberg
> > [mailto:grnbrg@cc*.UM*.CA*]
> > > Sent: Tuesday, March 14, 2000 9:43 AM
> > > To: mjblackmd@ya*.co*
> > > Cc: techdiver@aquanaut.com
> > > Subject: Re: Helium
> > > 
> > > 
> > > Michael J. Black writes:
> > > > Ben Wiseley wrote:
> > > > > I read somewhere that you needed the narcotic
> > properties 
> > > of nitrogen
> > > > > to off-set some effect of helium... (snip) But
> > for 
> > > recreational divers
> > > > > would heliox be preferred (assuming money was
> > no object)? 
> > >  In other
> > > > > words... if money didn't matter at all would
> > diving to 60 feet on
> > > > > heliox be safer than air?
> > > > 
> > > > The disadvantages of helium include increased
> > conductive heat loss,
> > > 
> > > Not true.  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.   In fact, a given volume
> > of HE will 
> > > absorb about 
> > > 70% of the heat than an equivalent volume of N2,
> > so net 
> > > effect is that 
> > > HE mixes may feel cooler, but in fact bleed off
> > less heat 
> > > than nitrogen mixes.
> > > 
> > > Cp (HE) --  20.786 Joules / Kelvin Mole
> > > Cp (N2) --  29.12 Joules / Kelvin Mole
> > > 
> > > CAVEAT:  While I've done the math, I've never
> > actually done a 
> > > mix dive.  Yet.
> > > :)
> > > 
> > > Brian.
> > > (Armchair diving at it's best.)
> > > --
> > > grnbrg@cc*.um*.ca*
> > > --
> > > Send mail for the `techdiver' mailing list to 
> > > `techdiver@aquanaut.com'.
> > > Send subscribe/unsubscribe requests to 
> > > `techdiver-request@aquanaut.com'.
> > > 
> > 
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> 
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