Now you did it opening that can of worms lol
Time to recover SAC after CO2 hit
- Thread starter Mr.Dave
- Start date
Now you did it opening that can of worms lol
Mr.Dave
New Member
Yer... I kind of hope I could get away with it :dj:
Mark Chase
ATB=AlwaysTalkingBollocks
I love reading about 80+LPM SACs
It reminds me that you just cant plan for everything and there is a point at which you just have to accept that if its your day? its your day
I call it shark atack
You just cant plan arround an attack by a great white on deco. You will die and thats that
50lpm SACs? your going to die
Dont fret about something you have no control over
When the flight atendent gives you the safety breefing? just read a book or check out the view because if that plane goes down from 30.000 feet your not going to make it to the nearest emergancy exit so whats the friging point of knowing where it is
ATB
It reminds me that you just cant plan for everything and there is a point at which you just have to accept that if its your day? its your day
I call it shark atack
You just cant plan arround an attack by a great white on deco. You will die and thats that
50lpm SACs? your going to die
Dont fret about something you have no control over
When the flight atendent gives you the safety breefing? just read a book or check out the view because if that plane goes down from 30.000 feet your not going to make it to the nearest emergancy exit so whats the friging point of knowing where it is
ATB
Mike Ferguson
WTF is that?
heres a link to an old thread that discusses this and gives a few peoples experiences. some of it makes interesting reading.
http://www.ccrexplorers.com/showthread.php?t=14094
http://www.ccrexplorers.com/showthread.php?t=14094
Mr.Dave
New Member
Makes good if not scary reading and brings home the necessity to respect CO2!
Ta,
D
Mr.Dave
New Member
Nice analogy, pesky sharks on every dive..
Guess its easier just to plan for 2-3mins at deepest point and pray any hit isn't that debilitating..
D
AlexBerger
Member
my 2 cents i use a co2 censor .... and yes i know it will not do end tidal bla bla. but it will tell me wen my scruber has a problem and it will do so before i need 500lpm that i dont have
Mark Chase
ATB=AlwaysTalkingBollocks
How does your C02 sensor identifie retained C02? How does it identifie mushroom valve failure?
Thats one of the reasions I have never bothered with one.
I know my scrubber limits, I pack in a repeatable way (tight fills) so I have little concern about breakthrough.
My issue is unit failure and the big one for me retained C02 due to WOB or work load related issue.
I always felt C02 sensors dont cover thease and would only lead me into over confidance / reliance on electronics.
My SAC gets over 15lpm for any reasion I cant explain Ill just bailout and worry aout the rest later
ATB
How accurate is it?
Mark, and that knowledge of the scrubbers actual limit for your usage, differs quite considerably from that published for the unit at a guess!
An inhale CO2 sensor physically can't, which is one reason why no manufacturer selling it has published any testing documentation: an exhale CO2 sensor does, but you need the elecs....
Mark, Without a respiratory rate sensor at the mouth how do you measure this? 15lpm is achieved barely finning hard. Loop with a minimum 4.5L breathable volume and you only need 3. breaths a minute...
AlexBerger
Member
well it dos not but tell me did you have your mushoom valves fail after you predive test them?and dos that happen cos it never did to me
AlexBerger
Member
well i cant remember but its one of foxs units so best to ask him thats fox@thebrain.net
AlexBerger
Member
sorry brat the last one was for you
Mark Chase
ATB=AlwaysTalkingBollocks
I have never had a head on crash in a car so does that mean it dosent hapen?
Ever coughed underwater? Thats about 2 ltrs of air mooving at 50mph in a fraction of a second
What effect do you think that might have on a mushroom valve?
What effect do you think a bit of phlegm would have on a mushroom valve
And that was just one example of a unit failure C02 hit
One diver had a C02 hit after a counterlung tie down failed causing the CL to float up too high and increase his WOB.
Mark Chase
ATB=AlwaysTalkingBollocks
Not realy.
I use the published data to calculate scrubber duration bassed on RMV water temperature & work load.
If your refering to the general cover all worst case scinario recomended max scrubber usage? Yes I dont bother with that but if I am ever at 40m in 4c water and breathing like a pedo in "Toys are Us", I am sure ill folow its guidance
How would a failure to eficiencently exhale C02 (retained C02) show up on an exhale moniter?
I dont know the exact RMV but I do know when I am not breathing normaly. Can I tell the diferance between my "normal" breathing and 20+ SAC? yes definatly I can and if I am doing that I will need a reasion as to why (work load or stress) or I will bailout imediatly.
Mr.Dave
New Member
.... if I am ever at 40m in 4c water and breathing like a pedo in "Toys are Us", I am sure ill folow its guidance
Sooo wrong, but O' how my side hurt... :haha:
Hi Mark,
Well, the idea is that at the beginning of exhalation you're exhaling the dead space (larynx, trachea, ..., no CO2), then you start exhaling gas coming from the lungs (so now there's CO2), and at the end of it (aka end-tidal CO2) you're exhaling gas that came closest to the alveoli, so is closest to equilibrium with arterial CO2. Normally, AFAIK, unless you're sick, it's 5-15% below. So you can extrapolate.
Retained CO2 would increase arterial CO2, so that would show up at the end of exhalation.
(I'm only 99% that arterial CO2 is necessarily an accurate measure of tissue CO2 at high ppO2, but I got thrashed by Andy Pitkin for asking about it, and he's the expert, so I'll shut up
)
I agree with what you're saying about scrubbers, but, personally, I wouldn't put faith in that last bit. A key take away (for me) from Simon Mitchell's Eurotek 14 presentation was precisely that people are not aware of their breathing rate, in some cases even when it goes through the roof.
At least not unless they're focussing on it.
Which is exactly what's not going to happen when they're distracted enough to run into retained CO2 problems.
Cheers,
Matthieu
Well, the idea is that at the beginning of exhalation you're exhaling the dead space (larynx, trachea, ..., no CO2), then you start exhaling gas coming from the lungs (so now there's CO2), and at the end of it (aka end-tidal CO2) you're exhaling gas that came closest to the alveoli, so is closest to equilibrium with arterial CO2. Normally, AFAIK, unless you're sick, it's 5-15% below. So you can extrapolate.
Retained CO2 would increase arterial CO2, so that would show up at the end of exhalation.
(I'm only 99% that arterial CO2 is necessarily an accurate measure of tissue CO2 at high ppO2, but I got thrashed by Andy Pitkin for asking about it, and he's the expert, so I'll shut up
)I agree with what you're saying about scrubbers, but, personally, I wouldn't put faith in that last bit. A key take away (for me) from Simon Mitchell's Eurotek 14 presentation was precisely that people are not aware of their breathing rate, in some cases even when it goes through the roof.
At least not unless they're focussing on it.
Which is exactly what's not going to happen when they're distracted enough to run into retained CO2 problems.
Cheers,
Matthieu
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DSix36
Well-Known Member
I am not trying to argue with Simon, but I tend to agree with Mark on this point. I have, like Mark, been a survivor of CO2 and can tell you that I am now very keen to monitor my SAC. I know damn good and well if I am breathing too hard for my current workload. Perhaps this is something that happens when you experience one of these events first hand rather than reading about it?
Johan Isaksson
Member
Lack of awareness is pretty common but for me it's unexplicable how people will not react to threefold increase in breathing rate. I know for a fact that I do notice as I've had both breakthrough and retained CO2 issues but in those cases bailed to oc (normalised breathing rate in <2 minutes) or in the case of the breakthrough stayed on just to see how it would play out for the next ten minutes. In all instances I've noticed this as an increased pace of about 30-50% above normal and even before that in a sense that something is wrong.
DeepUnderground
Member
On an mccr I notice I am injecting more o2 as the leak is failing to maintain set point if my breathing rate is increasing