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Re: Air Use Calculations
I have to agree with you, Gary. I don't think
it's worth the trouble or the money to build in a
scrubber when I'm only down for about an hour at a
time. If I were to get stuck on the bottom for longer
than that, I'm probably not coming back up again
anyways unless I flood the cabin n swim out. As far
as the "surface and replenish" thing goes, it seemed
pretty easy to just design in a couple of fans and
some ducts to circulate some fresh air in while on the
surface.
--- protek@shreve.net wrote:
> I find it unusual that so many people who plan
> to build small subs want
> to design the air rebreather system first. It seems
> like this is their
> first priority. The thought of diving without O2 is
> unthinkable to so
> many. But, depending on the volume of the air
> inside the hull, there is a
> time interval where one can breath the inside air
> only with no problems.
> Many subbers do this continuously with no use of 02.
> The SAR (surface and
> replenish) method has worked for me in my sub, but I
> don't go for long
> duration dives where more is needed. The cost of
> the materials for
> scrubbing for me would not warrant their use on
> short dives. In other
> words, for me personally, I would not even turn it
> on till I had been down
> long enough to need it.
> A no-scrubber time limit needs to be established
> though and adhered to.
> Also, one must realize that emergency situations
> may extend down time to
> greater duration than the SAR method can handle. In
> my case I have
> compressed air on board. This does raise the inside
> pressure if used and
> that is another problem I will admit.
> Scrubber systems do not take up much space in
> most cases. The main
> weight is the O2 bottle itself. If I were designing
> a sub again, I would
> leave space for the system and allow for the
> estimated weight but not
> concentrate on this systems fine details till I had
> a workable sub. Then
> if you choose to use a scrubber it can be installed.
> Once again, if you don't have a scrubber there
> is less safety built
> into your system. So I am not saying to not use
> one. I am saying that I
> don't in my sub. And IF (and that can be a big IF),
> I never have to sit on
> the bottom without the ability to surface, I will
> probably never need one
> because of the duration of my dives. Scrubber or no
> scrubber, if you do
> use the SAR method for a particular dive you should
> have an efficient
> method of purging the old air from the subs hull.
> Opening the hatch for a
> couple of minutes is not enough as the air does not
> have time to exchange.
>
> Gary Boucher
>
=====
"Noisy outside, empty inside." - Confucius
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