Dan:
i really respect you for what
you have done with your sub but you need to look at o2 saftey a little more in
depth.
It sound like you have expeience
with med o 2 and welding o2. but not high pressure o2. high velocity o2 can
ignite metal at room temp., your motor controllers are hot enough to ignite in a
high o2 enviroment. oil from a wrech used when changing bottles can cause an o2
fire. and just to say that it has not happen to you. will not stop it from
happening. My first rebreather suffered an o2 fire in the piping due to use
scuba tanks with quick opening valves. luckey it was durring testing
outside.nice flame thrower though
standard scuba valves are quick
opening and can cause scorching of regulators or piping ingition. open all o2
valves slowly. abs requires that o2 tanks be carried outside due to
pressure reasons and the risk of high o2 levels in the cabin. So you have high
pressure o2 entering the cabin at least above ambient.
the question of carry tanks
outside and forgeting to open them needs to covered durring the predive check.
flow check and pressure readings prior to dive. how many of us have hit the
water durring a scuba dive with our tank turned off. i did it once! only once.
now i always check again before i dive.
that all said o2 can be handled
safetly but it requires a hell of a lot more respect then nornal compressed
air
rick m
----- Original Message -----
Sent: Thursday, January 12, 2006 8:18
PM
Subject: Re: [PSUBS-MAILIST] Life
Support
Ross,
I haven't dived my sub any deeper then I could
escape from yet but soon will be. I'll be installing O2 and a scrubber
before I do.
Your correct, I couldn't last long trapped
inside.
Dan H.
----- Original Message -----
Sent: Thursday, January 12, 2006 5:05
PM
Subject: Re: [PSUBS-MAILIST] Life
Support
Dan,
I think I would be afraid to dive with no scrubber or oxygen.
What would happen if I get tangled on something and can't get back
up? By the time anyone realizes I am in trouble I could
suffocate.
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 leaki! ng
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 h! ad 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, Janu! ary 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 get! ting 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 ?o!
xygen 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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