On Friday, June 27, 2003 8:45 AM, Mike Wallace wrote:

Lee said
> > Having said all of that, I'm not sure why you would say there was a
> > lack of O2 due to no dilutent.  While dilutent would seem to add some
> > O2, so does the O2 portion of the system.  What did I get wrong and
> > how wrong did I get it?

> You are using a portion of the O2 in the loop with each breath. This used
O2 must be
> replaced or you will eventually use all the O2 in the loop. In the Dolphin
breather, the
> supply gas is Nitrox. Once the supply bottle is empty, if you continue to
breathe the
> loop gas you will eventually use the O2 to a point that it will not
sustain life.

G'Day, Mike!  An excellent way to bring that home - especially to divers
used to open-circuit who know when they're out of gas because they start
"sucking on lemons" - is to stay snug and warm in the shop and plumb a
cylinder of air into the rebreather.  There's no difficulty in inflating the
lungs, but after a very few breaths - and while you watch the O2 sensor drop
towards single digits - the onset of oxygen deprivation is really quite
alarming in the suddeness of the symptoms.  :-)

Strike