>If I could hazard a guess, why the Draeger Lar V is not used for deco, it
is
>that the fraction of O2 cannot be adequately controlled.


Well, that's not actually true. It's -almost- 100% as issued,
with a proper bag/lung purge of 4-5 cycles. A reduced
purge cycle results in more nitrogen, obviously.



>With a proper purge, a Lar V provides something like between 40 & 70 % O2,
>but there is no way to measure what you are getting, so your deco would be
a
>guess.


That is true in an unmodified rig. In a modified rig you install a oxy
sensor
and the bare enough electronics to monitor the PP02. Add a trimix diluent
bottle
as well and why carry OC bottles at all??? ;-)


>I definitely agree about the utter reliability, though. I'd love to have
>one, myself, for shallower dives.


It's cool, for sure. There are a few 02 rigs available from Russia
of all places, one (the IDA-59) looks like a horsecollar BC with
the scrubber and bottles on your chest. Takes up little space
and fits with a backplate no sweat. I'm going to experiment with
using one as a bailout rig for my Mark 15 rebreather. The IDA-59
has both nitrox/trimix bottle and pure 02 bottle so it can be used for
immediate bailout from the bottom as well as for pure 02 deco.
Cheap too. I'm getting a pipeline established and hope to have a
few on hand for sale semi-soon. I want to experiment with mine
before suggesting their use. But he rig as-is makes a cool pure
02 rig for shallow stuff like photography etc. Figure cost to be less
than a grand all set up. There are some 'coming attractions' too
but I don't want to spill the beans.


>I'll stick with 100% O2 from an open-circuit system for deco, though.


Well, my Lar weighs maybe 15 pounds (need to weigh it) and
is chest mounted so it does not interfere. And with 4-5 hours
of 02 available it seems like carrying OC oxygen is a waste of
drag. Hanging bottles is OK but ya better find the anchor line, eh?


Best,


Dave Sutton


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