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Rick,
As of yet, I don't have a scrubber or O2 supply in
my sub. For now, I never stay down with two people in the sub over twenty
minutes. That's my rule. I set a timer and return to the surface
when it times out. So in actually, it's about thirty minutes from closing
the hatch to opening it again. There is a pretty good cushion as I do
it. Besides, my wife is more comfortable with me touching base on a
schedule like that. (she muttered something about the life insurance not
being paid up or something) I had considered an O2 tank when building my
sub. It would be nice to extend my bottom time.
Kittredge used to carry a 02 tank inside his sub,
and then after the space capsule disaster, he moved it outside and piped the O2
in through a hull penetration to a valve in the sub. I was debating
when building my hull whether to put the through hull in or not. My
thoughts were and still are; a tank inside the hull is not leaking or it would
be empty. A tank outside of the hull would have to be turned on before
putting the sub in the water. The valve inside the hull may be leaking a
bit and I may not know.
Unless the tank or valve ruptures, I don't see the
danger of it being inside the sub. I know it's not leaking O2 at the time
I'm in the sub if it has sat in there for a month or so already. If I want
to extend my bottom time with supplemental O2 and discover my tank is empty I
have to surface and go back to my twenty minute schedule. I could carry
two smaller medical tanks.
Any thoughts?
Dan H.
----- Original Message -----
Sent: Wednesday, January 11, 2006 9:41
PM
Subject: Re: [PSUBS-MAILIST] Life
Support
harry
The normal human consumes
about one cubic foot of oxygen per hour and will feel no effects of oxygen
deprivation at an o2 level above 18% the osha level is 19.5% minimum. air
contains 21 % o2. So dependent upon the size of your cabin you need to run the
numbers to see how much o2 you will have.
A co2 scrubbber can be made
from a piece of plastic pipe with screens at the end to hold the absorbent.
mount a fan at the top and for under 100$ you have a co2 scrubber.
one caution when using
o2 addition it does make things burn rapidly. and abs says that o2 tank
most be mounted outside.
fire and o2
the biggest problem using pure
o2 is the risk of fire in the system piping. high velocity o2 can ignite lots
of things . needle valves are used here. Trust me on this i turned a
rebreather in to a flame thrower the hard way.
most valves can be ordered o2 clean and should
be, the packing and grease needs to be o2 compatible. yes o2 needs a special
grease. piping will need to be cleaned prior to use. I have had success with
hot soapy water wash, repeat until clean then hot water rinse and cap lines
until installed.
hope this helps
rick m
----- Original Message -----
Sent: Wednesday, January 11, 2006 2:51
PM
Subject: [PSUBS-MAILIST] Life
Support
Hello folks,
It has been a long time since
my last post but I still have questions!
Is it correct to think that in
an enclosed space, like your pressure hull you will suffer from the negative
effects of excess CO2 before you suffer from a lack of O2? What I am getting
at is, could you upgrade a simple sub with no life support by adding just a
scrubber to extend your usable bottom time or would you only gain a little
bit of extra time before the O2 would need replenishing as
well.
What sort of equipment is used
by those of you who do replenish the O2? It is sufficient to have an O2
tank, conten gauge, regulator (and gauge?), and a flow meter (with a
separate O2 sensor and meter). Or does the equipment need to be more
sophisticated than this.
What do you do about ?oxygen
cleaning? Do you have to just concentrate on the O2 supply kit or all of the
equipment within the sub?
How many of you provide
yourselves with CO2, O2, and internal pressure gauges to monitor the
environment but do not fit additional life support.
Thanks in advanced
guys,
Harry
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