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----- Forwarded message from "Sean T. Stevenson" <sts@te*.ne*> -----
    Date: Fri, 25 Oct 2002 12:20:40 -0700
    From: "Sean T. Stevenson" <sts@te*.ne*>
Reply-To: "Sean T. Stevenson" <sts@te*.ne*>
 Subject: Re: Heliox
      To: Richard Waring <newkitric.hellsbells@vi*.ne*>

Why would you have air on you to break to in the first place?

Heliox is a great way to go if you can do this.  Most of us don't use it for 
purely practical reasons, since you need very high helium pressures to get the 
deep bottom mixes, which requires having a booster.  Also, the low narcotic 
depth that heliox provides is overkill in many cases, not that it would be a 
bad thing, but for those of use who don't have access to cheap helium, it gets 
to be a cost issue with minimal benefit.

Having said that, I still put helium in my decompression gases, because I feel 
better after the dives.

As for the breaks, the intent here is to allow your lungs to reset and prevent 
damage which reduces the efficiency of the high PPO2 intervals, so you can get 
back on the high PPO2 and reap the benefit of the large oxygen window.  Maximum 
benefit here is achieved by breaking to the gas with the lowest breathable 
PPO2 - meaning a gas you are already wearing and used elsewhere in the dive - 
likely a trimix, or heliox if you chose to do that.

To repeat a common opinion here -- air is good for running tools and inflating 
tires.  For diving, we put a little more thought into gas selection.

-Sean


Quoting Richard Waring <newkitric.hellsbells@vi*.ne*>:

> While the list is quiet I have a question aimed mainly at Trey, I know one of
> your team uses heliox and wonder why you don't. On the same subject if I have
> dived heliox back to 6 meters and switch to pure o2 am I better off braking
> on to air or going back to helix I know there is a problem with counter
> diffusion if I use air but don't understand the full implications. Ric
> Waring



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