----- Original Message -----
Sent: Tuesday, December 20, 2005 10:51
AM
Subject: Re: [PSUBS-MAILIST] o2
control
In support of Hugo's response, Keep It Safe and Simple (and
cheap) - The KISS formula.
Taught to every first year engineering
student.
The metre shown below is dead easy to use
(no pun intended). There is a little black ball that floats up the
graduated glass tube. You want 4 litres? Turn the little knobby
until the black ball floats up to "4" and, well, breathe.
Air fouled in the cabin? Slip an oral/nasal
mask onto the nipple that screws onto the threaded fitting at the
bottom. The nipple costs, oh, about $0.25 USD
:-) I'm sure they'll throw that in. The
metre too far from the cockpit seat for the mask? Run an 02 extension
line (about $1.00) from the flowmetre to the instrument panel. Plug
your mask in there. Hell, forget the buck
- I'll acquire one for you and mail it to you.
Broken? Unscrew it by hand from your wall
mount. Really broken? Replace it for $51 USD.
No computer, no electronics, no power supply, no
software failures, NADA NADA NADA.
Enjoy
Rick L
Vancouver
Oxygen Flowmeter
These
precision Medical Flowmeters are available in both a rugged chrome plated
brass and an aluminum body model. Features a 0-15 LPM flow rate, Lexan
flowtube and positive shut-off control valve that will not drift from a set
flow rate over extended durations. [More
Info]
----- Original Message -----
Sent: Monday, December 19, 2005 11:49
AM
Subject: RE: [PSUBS-MAILIST] o2
control
Hey guys,
I
assume that just about everyone here is limited in funds to build your sub.
The more complex systems are their likelihood to fail is higher and the cost
of repair is equally expensive. An O2 System does not have to be so complex,
all you need is a needle valve in series with a flow gauge (calibrated for
O2) for you to set the proper flow. There are all kinds of portable O2
monitors that you can get for $200 bucks and that is what you use to keep an
eye on your O2. They even have Low and high and low level alarm settings
which if set properly will give you plenty of time to adjust your O2
flow.
In
my personal experience with many submersibles I have yet to see an automatic
computer-controlled O2 system aboard any of the submersibles that I have
worked with. And the comments I have heard from the ones that do have it is
that they are a pain in the ass to maintain. I am not against it as I am a
tech junkie myself. However one must ask the question..... Is this really
necessary? Do I really need it? Or is it just a gadget I like?
The JSL sphere is roughly 55 cuft and I rarely ever
have to make an adjustment to the O2 system. I have even turned off the O2
to see how long it takes to trigger a low alarm (Ours is set at 19%) and it
takes about 30 minutes to drop 2%. However, it is a good piloting practice
to monitor your instruments constantly (every 5 minutes is a good ballpark
figure). I guarantee that this practice alone will keep you out of trouble
and on top of your life support system with very little
maintenance..
Any ways, just a thought...
Hugo
brian
the sensors that you are
looking for are teledyne analytical instruments
class r-22d, o2 sensors. they put out a milli
volt singal directly perporsional to the amount of o2 present the
average output is 7-13 mv in air at stp. the need to be loaded with a
10k resister. Measure the output with a milli volt meterany kind will
do. if the voltage drops ten percent you know that your o2 levels
droped ten percent.
o2 control can be done three
ways.
1.o2 level monitoring with a
solinoid for injection
pros
hands off automatic control
cons
expensive and complex
2. automatic pressure
controller maintain sub internal pressure to a fixed
point
pro
single controller all mechaincal/ about half price of
electrical
con
compressed air leak internal inside sub will shut down
system
3. adjustable flow
controller manual
pro
cheapest
con
requires continous monitoring
hope that this helped for your design
ideas
rick
m