----- Original Message -----
Sent: Friday, January 13, 2006 5:26
AM
Subject: Re: [PSUBS-MAILIST] Life
Support
Rick!!!!
Hang on there, I'm here to learn
also! I only stated what I have found and how I concluded what I have
concluded.
I sure don't claim to know all about any subject,
much less O2. In fact, what I stated was about ALL I know about
O2.
So then, am I correct when I say that, gathering
from you posting, high pressure O2 is more apt to self ignite something then a
high O2 environment at atmospheric pressure?
When a gas is decompressed it cools and that
sort of goes against the theory that a blast of high pressure O2 is more apt
to cause combustion, but on the other hand, there would be friction of the O2
molecules as they were racing through a valve. Again referring to
my torches, there is a HP bottle with a regulator that reduces the 2000+
PSI O2 to 40 PSI. That regulator neither gets hot or cold.
So where is the actual danger with O2? Is
it when it's being decompressed from it's tank or when it's surrounding
something combustible? Or, is the ABS rule about tanks
outside the hull there because of the problems you could have with an
uncontrolled release of any pressurized gas in to an enclosed occupied
space?
Are you sure there wasn't something more that
ignited you flame thrower rebreather.... like a chemical reaction that touched
off the fire in the first place?
Not professing to know anything about anything,
Dan H
----- Original Message -----
Sent: Friday, January 13, 2006 12:26
AM
Subject: Re: [PSUBS-MAILIST] Life
Support
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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