[PSUBS-MAILIST] life support test
hank pronk via Personal_Submersibles
personal_submersibles at psubs.org
Mon Mar 19 04:27:46 EDT 2018
Brian,Those are great readings, your scrubber is working great! Hank
On Sunday, March 18, 2018, 8:45:50 PM MDT, 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 drinking1 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 mightconfirm this). It would be much easier to see how many Martini's you coulddrink & 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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