[PSUBS-MAILIST] life support test

Mon Mar 19 10:30:24 EDT 2018

Looks like progress on qualifying your life support system.  A couple of
observations.  Your scrubber looks like it is controlling the CO2 level
nicely.  Humidity build looks normal.  If you would have stayed in the boat
longer, it would eventually plateau.  The only thing that looks a little
weak to me is the O2 concentration.  It looks like your O2 makeup rate was
a bit high, i.e., you are making up more O2 than you are consuming.  If you
looked at your results on a linear basis, the O2 would have reach the
maximum acceptable ABS O2 concentration of 23% at 3.75 hours.  Well short
of the ABS 72 hour target.  Not sure how you are controlling O2 makeup.
The next thing I would do is do a longer test say 8-9 hours or how ever
long it takes for your initial fill of CO2 absorbent to become saturated.
The next test I would suggest is how long does it take for CO2 to build to
5000 ppm when O2 if off.  Would also suggest you measure and report cabin
pressure as this would tell you if you have a gas leak into the cabin.
Also I would log the data more frequently say every 10 minutes to improve
data analysis.  You have  nothing better to do while sitting in the boat.
Also you might want to consider repeating the test with a low weight pilot
to see how the system handle variation in CO2 generation and O2 consumption
rates.

Keep up the good work.

Cliff

On Sun, Mar 18, 2018 at 9:45 PM, Brian Cox via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hi All,
>                I did a life support test today !   Basically I threw a
> small party with a couple of friends and my wife.  I was sealed in the sub
> for a total of about 2 1/2 hours .
>
>
>
>   At the hatch closing time the readings were:
>
> O2  -    20.6 %      CO2 1225 ppm          Temp 79 F          Humidity
> 50 %
>
>
> In one hour the readings were:
>
> O2   -  21.4 %             CO2  1365 ppm          Temp79
> humidity    63 %
>
>
> At hour 2  readings were:
>
> O2   -   22.2 %               CO2  1750 ppm          Temp 77 F
> humidity  70 %
>
>
> After  2 1/2 hours readings were :
>
> O2  -    22.2 %                CO2  1785 ppm            Temp 76
> humidity   70 %
>
>
> Brian
>
>
>
>
>
>
>
>
>
>
> --- personal_submersibles at psubs.org wrote:
>
> From: Stephen Fordyce via Personal_Submersibles <
> personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.
> org>
> Subject: Re: [PSUBS-MAILIST] life support test
> Date: Mon, 19 Mar 2018 10:59:31 +1100
>
> Hi Alan,
> Agreed the martini test probably is easier although I think that model is
> going to deviate the further you go.
>
> I had a friend (very experienced deep air diver) who was pushed to
> 60m/180ft by a current and he literally didn't have the mental faculty to
> save himself (he was fortunately holding a rope which I pulled up).
>
> If you're even still conscious breathing air at 100m/300ft you're doing
> pretty well. High oxygen seizures start to become a real risk beyond 70m on
> air, quite apart from how debilitating the narcosis will be.
>
> Cheers,
> Steve
>
> On 19 Mar 2018 10:23 am, "Alan via Personal_Submersibles" <
> personal_submersibles at psubs.org> wrote:
>
> Steve,
> you are advocating a nitrogen narcosis experience as a training for escape.
> Nitrogen narcosis is known as the Martini effect & is equivalent to
> drinking
> 1 martini on an empty stomach for every 10 metres you descend.
> I think a standard Martini is 3 oz, (some of the alcoholics in the group
> might
> confirm  this). It would be much easier to see how many Martini's you could
> drink & still get out of your sub, than try & do a real simulation with
> nitrogen.
> For those with K250s that's about 5 Martini's & K350's 8 at maximum depth.
> I am shooting for 500ft so that's 12. (36oz)
> How deep is Scott going?
> Cheers Alan
>
> Sent from my iPad
>
> On 19/03/2018, at 11:02 AM, Stephen Fordyce via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Brian and all,
> I'm just going through commissioning a new/modified rebreather which is a
> bit relevant to this. I believe (sort of at odds with conventional training
> manuals) that it's valuable to experience the physiological signs and
> symptoms of the various gases at incorrect levels. Your other systems
> should of course protect you and be highly conservative, but you never know.
>
> To that end, after a recent long dive I continued to breather the scrubber
> at home on the couch (for several hours) until the high CO2 effects were
> noticeable. I've also had a controlled low oxygen experience that I
> consider valuable. Both worth doing, maybe even regularly - I'd like to do
> high oxygen one but that's been a bit tricky so far.
>
> If anyone has plans to be exiting a partially flooded sub at depths below
> 30m/100ft then a nitrogen narcosis experience would be extremely valuable.
> Especially with quick compression, your mental faculties deteriorate
> rapidly. Even at that depth, and it gets worse as you go deeper. I don't
> dive below 50m on air because I barely know what I'm doing.
>
> Cheers,
> Steve Fordyce
>
> On 18 Mar 2018 2:04 pm, "Cliff Redus via Personal_Submersibles" <
> personal_submersibles at psubs.org> wrote:
>
> See
>
> *DESIGN GUIDELINES *FOR
>
> CARBON DIOXIDE SCRUBBERS
>
> I
>
> MAY *1983*
>
> REVISED *JULY 1985*
>
> Prepared by
> M. L. NUCKOLS, A. PURER, G. A. DEASON
>
> for the philological affects of high CO2 level but if you abort the test
> if you ever exceed 5000 ppm, you should be safe.  In addition to the CO2
> issues, you should also familrrize yourself with both *Hypoxia* which
> describes levels lower than Normoxia, or percentages lower than 21% and
> *hyperoxic* breathing gas when levels rise above 22% of oxygen. Hypoxia
> would come from running out of makeup O2 or leaving the O2 supply valve
> closed by accident and hyperoic state would most likely be caused by a high
> pressure leak of O2 into the cabin caused by a loose fitting.  I would
> recommend you abort the test if O2 concentration falls outside the
> acceptable range as defined by ABS.
>
> When you go back and analyze the test, it is helpful to have data logged
> cabin atmosphere parameters including, CO2 and O2 concentrations, cabin
> pressure and temperature and relative humidity.
>
> Cliff
>
>
> On Sat, Mar 17, 2018 at 5:37 PM, Brian Cox via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi All,
>               Thinking about testing my life support.  Will obviously have
> some people outside the sub watching me, and talking via radio.  But I was
> wondering if there would be a point at which I should abort the test when
> the CO2  gets to a certain point .   If it levels off and stays at a
> constant but is some what elevated would it be ok to monitor that situation
> ?   Like say it levels off at 2000 ppm and assuming my oxygen is at a
> constant 20.8 %    ?
>
> Brian
>
>
>
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