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Alan,
One thing is to breathe nitrox as a diver, but another
would be to flood a compartment with it. A 40% O2 concentration will combust if
you do something like flip a switch that produces an arc. I'd suggest you
build the life support for an ambient boat just like one would for a 1
atmosphere boat. Keep the O2 concentration within a 18-23% range. See
Phil's white paper.
Or for a simple solution, just have a continuous bleed air
system like on Pierre Poulin's boat.
thanks,
Alec
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From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Alan
James
Sent: Tuesday, August 11, 2009 4:17 AM To: personal_submersibles@psubs.org Subject: [PSUBS-MAILIST] Ambient running on nitrox Hi psub experts,
What do you guys think of the idea of running an
ambient subs life support on nitrox?
I'm building a very small fiberglass sub, almost
canoe like. Eventually I want to build it 1 atm but
thought it would be smart to try the design
out as an ambient first.
There might be close to 200 liters of air
space in the hull. I have 2 x 80cubic ft tanks. If I filled them
with
40% O2 it would take 2hrs 40min for the air to get
down to 21% O2. This is in the worst case scenario of traveling
just
under the surface. At 33ft I'd have 5hrs 20min etc.
I could open a valve & flush the system any time & in the
normal
course of a dive this would happen as the air
expanded on ascent & filled on descent.
There is a dive limit of round 90ft with nitrox but
longer no decompression times. However I guess I would need
to stay inside this depth limit & keep to the
air decompression tables to stay safe.
On the plus side, I won't have to get anything
02 cleaned, & its pretty simple.
Alan
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