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>> One more thing: I keep the dump valve with the maximum resistance, and I do
>> not overfill the canister. Actually the marker line in the scrubber
>> canister is too high, if you put 1 cm/0.4 inches less scrubbing material,
>> you get 2 results:
>>
>> 1) Decreased breathing resistance (less compression of DraegerSorb) and
>> that means less pressure build up in the exale bag, (less gas will be
>> dumped overboard)
>>
>> 2) Again: less compression of DraegerSorb, which also means less pressure
>> stress on the canister itself, the canister will not be deformed at the
>> top, and you obtain a better seal, (less leaking!)
>
>Doesn't this also mean that you have a greater probability of incorrectly
>packed absorbent, leading to increased chance of channeling, leading to
>an increased chance of CO2 buildup?  Maybe this doesn't matter as much on
>a semi-closed unit, but on a fully-closed, canister packing has to be
>done carefully and correctly.  Seems to me Draeger probably had a reason to
>put the fill-line wherever they did.
>
>Aloha,
>Rich

Not really, but maybe I didn't express myself corrctly. There are still
minor problems with the Atlantis I.
The fill-line is a bit to high, if you put 1 cm or 0.5 cm less DraegerSorb,
the springs that keep the pressure plate has more then enough power to keep
the scrubbing material in place, without any channeling problem. The real
problems are those springs, they are too strong for the canister plastic,
and it will get deformed soon or later. Maybe Draeger has corrected the
problem with the new units, I got my unit late March this year, and
Uwatec-Draeger, said they were going to change the Scrubber unit plastic
with a more solid one. Then the fill-line could be used as it is.
Of course reducing the quantity of scrubbing material will reduce the
operational time of the unit, but we use a very conservative limit on the
scrubber anyway.

Another little problem with this unit is the continuos flow valve, actually
the metal ring wich hold the little filter in his position, it is not made
of good steel, it tends to rust and the filter gets dirty.
Result: you get a lower flow! We had the problem with one unit, and the
flow dropped from 7.2 L. a min to less than 5!! And this is dangerous.
The same kind of metal ring was used to keep the counter screw in place
inside the lid of the canister, but this is easy solved changing it with a
standard O-ring (Viton of course), but the low O2 pressure in the scrubber
will allow a silicone O-ring.
Plus there is another little trick but I'm getting boring now..

Now a question: Biomarine or Cis-Lunar? And then, how would you start?

PS: the Scud has been around a while now, every now and then it pops out
again, let's see! Plus there is a Russian unit, an Italian unit, a Japanese
one, etc. What is going on?

Saluti (Greetings)

Roberto

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