SCR/VSC as a CCR Bailout Method

**Dave Sutton** · 1st January 2008, 15:28

Quote: (Originally Posted by jradomski)

Also remeber the student is taught that whenever possible switch to O2 and run it as an o2 rebreather starting at 6m... If you have O2 there is no reason to run SCR from this point on..

If you had 02, there was probably no reason to do SCC to begin with either...

. Scrubber bad, maybe..... not lost gas though.

Dave

**Dave Sutton** · 1st January 2008, 15:39

Quote: (Originally Posted by HMC)

electronics dead maybe (you know a bit of salt water... not a full flood)?

Easy to do using a CCR, with no electronics, and not going to SCC. If you can add 02, you can dive CCR without electronic monitoring *in an emergency*. Yes, it's an *experts* technique, and in deference to Mark Nix's counseling session that he gave me at the quarry about a year ago (Dec 31 a year ago, actually the "Last Ditch at Dutch"), I'm not gonna publish this stuff here because, as he said, "people are going to try it who ought not to, and they are gonna get hurt".

With that said, Tell me how.... I already know (and have practiced it lots, in fact on most decos).
Your turn to teach us. Impress us with your depth of knowlage.

Not taught that yet? Maybe it's time to, as my Grandpop said: "siddownandshaddupandlistenfuroncefurchrissake "

There are people here who developed these techniques and never read about them in a book.
Methinks you need to figure that out.

Dave

.

Dsix36 · 1st January 2008, 15:53

Quote: (Originally Posted by Dave Sutton)

Easy to do using a CCR, with no electronics, and not going to SCC. If you can add 02, you can dive CCR.

Tell me how.... I already know (and have practiced it lots, in fact on most decos).
Your turn to teach us. Impress us with your depth of knowlage.

Not taught that yet? Maybe it's time to, as my Grandpop said: "siddownandshaddupandlistenfuroncefurchrissake s"

Dave

.

I wanna take a shot at this one:

Maintain minimum loop volumn by merely injecting O2 as the loop diminishes from O2 metabolism. My depth would have to remain reasonably consistant though.

Did I win?????

Hanssing · 1st January 2008, 16:03

Quote: (Originally Posted by HMC)

I tried air (21% FO2) on the surface 5 breaths + nothing and it does not go below 18% - perfectly safe (but I was not joggin on a threadmill...).

Just did the same 1:5 and the loop ended up below .16ppo

Stopped when I got dizzy.

Hoever exhale from air was app. .18-.19 so I remebered wrong thinking it would drop from 0.21 to 0.16 in one breath. This is good new - gives higher ratios :-)

For air say 3 x AbsPressure....

Quote: (Originally Posted by jradomski)

Thats been my experience as well, even with doing LIGHT work..The worse I have seen a student do in the shallow end of a pool using air was .16-.17 and the student's technique was poor (uneven refils/flushes and screwed up counts)

Did one full breath from empty loop.... Would offcourse have been better with more loop volume but that equates to higher gas-use....

Quote: (Originally Posted by Dave Sutton)

To Joe's Quote: Stay alive first, stay in a known deco situation second. As far as staying alive, viability of the loop is anywhere between 2.0 and 0.18 or so. The guys who only want to discuss the methods that maintain a more or less constant fraction 02 in the loop so they can simplify their deco are only doing half the learning. The guys who can do that *and* also extract every molecule of 02 *simply in order to stay alive* have two tools as their disposal.

So.... figure that out too. And then take a look at how diluent selection can adversely or proversely affect survival durations using diluent- only SCC modes. Then go back and re-read the lean v/s rich diluent debate of last year. It all fits together.

I clearly remember that debate, and I was thourougly told off by my instructor when discussing DIL-selections during my mod one.
Also the cell-validation comes to mind.
I however was told: Air or 10/50 as dil was the way to go.....

I still think its overly complicated, and what youre after Dave (constant PO2 close to 0.18) is archivable, but I think its a bit harder and really non-deco friendly, and breathing the loop that far down is allso more dicey. But usefull to be able to do - yes.

One way I could think up:
Go out, flush the loop, and time how many breaths it takes for the loop to drop 1.0bar PPO. Call it B1 (Say 30).
OK at depth calculate current gas PO2.
Substract 0.2 scale by B1:
Do the no of breath, then looplush. Rinse and repeat.

Example:
Air @ 30msw => PO2 = 0.84bar ie. (PPO-0.2)*B1 = 0.64*30 = 19:1 ?
EAN30 @ 36msw => PO2=1,38 ie. 1,18*30 = 35:1 ?

***added***
One should allways meassure drop-count with the leanest gas in use, and meassure down to the leanest fraction (ie. as close to 0.2 as one is comfortable with) and either only use this as a scale for all gasses, or meassure for other frequently used gasses, and keep track of the B-values.
Just an idea anyway....

Quote:

There's nothing new under the sun, guys... if you don't know all the tools, you're only partially trained. One day you might NEED to know how to do it.
And, uhh..... not to be too stereotypical, but is it just me or do other see the same old stuff: Newly trained Kool-Aid drinkers with a tiny bit-o-experience thinking that they have been taught by the only true master, and that only the masters word has value.....

If I know all the tool, and I UNDERSTAND all the tools, Im still not trained at all

And you were allso a newbie once - so give us some leeway.
Actually strike that - you were probly never a newbie, but please give us some leeway anyway

Quote: (Originally Posted by jradomski)

Also remeber the student is taught that whenever possible switch to O2 and run it as an o2 rebreather starting at 6m... If you have O2 there is no reason to run SCR from this point on..

Yes, but the formula IMVHO is not very intuitive, and I really dont understand WHY it is taught, unless the student is also taught that it should not be used unless PO2 is above X.....

My point was exactly that if O2 was not available then the student could try to use it, and without realising its limitations could become hypoxic.

--------------------

I know I'm an annoying newbie, but I'm really learning from this so please put up with me

BTW: anyone figure out why I drove my instructor (Rasmus) to the brink off insanity while doing my mod 1, hehe?

Regards
Nicolai

***jradomski*** · 1st January 2008, 16:04

Quote: (Originally Posted by Dsix36)

I wanna take a shot at this one:

Maintain minimum loop volumn by merely injecting O2 as the loop diminishes from O2 metabolism. My depth would have to remain reasonably consistant though.

Did I win?????

as long as the o2 is 100%.. if you are at a constant depth this works fine, but if you are changing depths SCR is a better choice.. This technique also has it problems if you are shallower than you were.. IE during deco.. SInce you are offgassing inert gas INTO the loop.. In this case frequent dil flushes (or a deco gas) with manual o2 addition could be used..

Lots of different techniques CAN be combined once each individual one is MASTERED and PRACTICED.. You use the best for what you have..

the 5:1 plus 1/atm is for simplicity (especially when metric).. As the persons skills and understanding grow, they can build on the foundation set in place..

**Dave Sutton** · 1st January 2008, 16:17

Quote: (Originally Posted by HMC)

Dave, how would your technique get me out of the predicament?.

The short answer is that you don't know how to do it because it's not "in the book"... so you don't see the value to it. Maybe the only value is being able to write a longer good-bye letter to your wife! But I'm going to put off drowning as long as possible... and I'll be alive a lot longer than you are.

These hypotheticals have more than practical value, so don't blow them off. At the very least they are an advanced intellectual concept to think about, because excercising your *brain* on things like this helps build the habits and knowlage that might be useful one day when you are confronted with a situation that you were not specifically trained to deal with.

Back tomorrow late. Have fun with the regularly scheduled rant one and all.

Dave

.

**Dave Sutton** · 1st January 2008, 16:22

Quote: (Originally Posted by Hanssing)

I still think its overly complicated, and what youre after Dave (constant PO2 close to 0.18)

That's not at all what I am looking for....

As a *more desperate survival technique* than the basic 5:1+atma SCC mode, I am asking you to use your brain to come up with a way to let the loop slide from *whatever the raw diluent PP02 is after a full flush* down to *the point where it's no longer able to reliably maintain life*, and then re-flush and let the cycle start again. It's a constantly varying PP02 survival mode... that's all.

Figure it out and let me know when you're done. A "Diver Dave Seal of Approval" waits the successful calculation. It needs to be able to be done "in your head" while scared...

I am NOT suggesting that this be anything other than an absolutely last-ditch method. If access to the surface is available, the 5:1+atma is going to be my choice as well. Really, it would be a bad day to even get that far. I just like every ace in the deck to be in my hand.

Dave

.

Hanssing · 1st January 2008, 16:32

Quote: (Originally Posted by Dave Sutton)

I am asking you to use your brain to come up with a way to let the loop slide from *whatever the raw diluent PP02 is after a full flush* down to *the point where it's no longer able to reliably maintain life*, and then re-flush and let the cycle start again. It's a constantly varying PP02 survival mode... that's all.

By constant PO2 i mean constant beforere each flush (PoTaToe...)
We can also callit "constantly varying PP02", or constant average PO2....

(DIL_PPO-0.2)*B
Good enough answer? Only thing is you need to measure B beforehand.

Dsix36 · 1st January 2008, 16:37

Quote: (Originally Posted by HMC)

hmmm... let us keep it simple... if you did that at 6 meters with O2 without doing ever a diluent flush... would you live or die?

I would live at any depth. The PO2 would remain the same as when I began the procedure.

PO2 could be calculated with dil at depth to know what it is after a loop flush also. Then just maintain with O2 injection, but this will only work when my depth doesn't change.

***jradomski*** · 1st January 2008, 16:41

Quote: (Originally Posted by Hanssing)

I clearly remember that debate, and I was thourougly told off by my instructor when discussing DIL-selections during my mod one.
Also the cell-validation comes to mind.
I however was told: Air or 10/50 as dil was the way to go.....

Yes, but the formula IMVHO is not very intuitive, and I really dont understand WHY it is taught, unless the student is also taught that it should not be used unless PO2 is above X.....

My point was exactly that if O2 was not available then the student could try to use it, and without realising its limitations could become hypoxic.

Regards
Nicolai

Firts ANDI teaches to use the right diluent for the dive.. 10/50 for a 60m dive isnt optimal even at 100m Im using 13/50..

secondly the calculation is EASY for you metric folk.. move the decimal place one spot and you have how many breaths to add to 5.. even if someone was really narced they cound do this..

even using say 10/50 at 21m.. its still going to be a breathable gas at 7 breaths.. not that I would use it here.. My deco gas would be plugged in..

at 10m a 10/50 is a .20, if you aren;t working and have good technique, the lop should still be breathable.. Diluent selection and contingency planning should be part of every Mix class.. This becomes even more important once hypoxic mixes begin to be used..

If I was stuck at 10m with only a hypoxic dil and my offboard o2, I would do an approximate mix on the fly.. It can be done with practice and a bit of planning.. But here you need to know the ratio of a breath to dead gas space..

1st January 2008, 15:28	#61 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by jradomski) Also remeber the student is taught that whenever possible switch to O2 and run it as an o2 rebreather starting at 6m... If you have O2 there is no reason to run SCR from this point on.. If you had 02, there was probably no reason to do SCC to begin with either... . Scrubber bad, maybe..... not lost gas though. Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
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1st January 2008, 15:39	#62 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by HMC) electronics dead maybe (you know a bit of salt water... not a full flood)? Easy to do using a CCR, with no electronics, and not going to SCC. If you can add 02, you can dive CCR without electronic monitoring in an emergency. Yes, it's an experts technique, and in deference to Mark Nix's counseling session that he gave me at the quarry about a year ago (Dec 31 a year ago, actually the "Last Ditch at Dutch"), I'm not gonna publish this stuff here because, as he said, "people are going to try it who ought not to, and they are gonna get hurt". With that said, Tell me how.... I already know (and have practiced it lots, in fact on most decos). Your turn to teach us. Impress us with your depth of knowlage. Not taught that yet? Maybe it's time to, as my Grandpop said: "siddownandshaddupandlistenfuroncefurchrissake " There are people here who developed these techniques and never read about them in a book. Methinks you need to figure that out. Dave . __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 1st January 2008 at 15:54.
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1st January 2008, 15:53	#63 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 1,154	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by Dave Sutton) Easy to do using a CCR, with no electronics, and not going to SCC. If you can add 02, you can dive CCR. Tell me how.... I already know (and have practiced it lots, in fact on most decos). Your turn to teach us. Impress us with your depth of knowlage. Not taught that yet? Maybe it's time to, as my Grandpop said: "siddownandshaddupandlistenfuroncefurchrissake s" Dave . I wanna take a shot at this one: Maintain minimum loop volumn by merely injecting O2 as the loop diminishes from O2 metabolism. My depth would have to remain reasonably consistant though. Did I win????? __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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1st January 2008, 16:03	#64 (permalink)
Hanssing flap-flop ..... flap-flop Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Denmark Posts: 430	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by HMC) I tried air (21% FO2) on the surface 5 breaths + nothing and it does not go below 18% - perfectly safe (but I was not joggin on a threadmill...). Just did the same 1:5 and the loop ended up below .16ppo Stopped when I got dizzy. Hoever exhale from air was app. .18-.19 so I remebered wrong thinking it would drop from 0.21 to 0.16 in one breath. This is good new - gives higher ratios :-) For air say 3 x AbsPressure.... Quote: (Originally Posted by jradomski) Thats been my experience as well, even with doing LIGHT work..The worse I have seen a student do in the shallow end of a pool using air was .16-.17 and the student's technique was poor (uneven refils/flushes and screwed up counts) Did one full breath from empty loop.... Would offcourse have been better with more loop volume but that equates to higher gas-use.... Quote: (Originally Posted by Dave Sutton) To Joe's Quote: Stay alive first, stay in a known deco situation second. As far as staying alive, viability of the loop is anywhere between 2.0 and 0.18 or so. The guys who only want to discuss the methods that maintain a more or less constant fraction 02 in the loop so they can simplify their deco are only doing half the learning. The guys who can do that and also extract every molecule of 02 simply in order to stay alive have two tools as their disposal. So.... figure that out too. And then take a look at how diluent selection can adversely or proversely affect survival durations using diluent- only SCC modes. Then go back and re-read the lean v/s rich diluent debate of last year. It all fits together. I clearly remember that debate, and I was thourougly told off by my instructor when discussing DIL-selections during my mod one. Also the cell-validation comes to mind. I however was told: Air or 10/50 as dil was the way to go..... I still think its overly complicated, and what youre after Dave (constant PO2 close to 0.18) is archivable, but I think its a bit harder and really non-deco friendly, and breathing the loop that far down is allso more dicey. But usefull to be able to do - yes. One way I could think up: Go out, flush the loop, and time how many breaths it takes for the loop to drop 1.0bar PPO. Call it B1 (Say 30). OK at depth calculate current gas PO2. Substract 0.2 scale by B1: Do the no of breath, then looplush. Rinse and repeat. Example: Air @ 30msw => PO2 = 0.84bar ie. (PPO-0.2)B1 = 0.6430 = 19:1 ? EAN30 @ 36msw => PO2=1,38 ie. 1,1830 = 35:1 ? added* One should allways meassure drop-count with the leanest gas in use, and meassure down to the leanest fraction (ie. as close to 0.2 as one is comfortable with) and either only use this as a scale for all gasses, or meassure for other frequently used gasses, and keep track of the B-values. Just an idea anyway.... Quote: There's nothing new under the sun, guys... if you don't know all the tools, you're only partially trained. One day you might NEED to know how to do it. And, uhh..... not to be too stereotypical, but is it just me or do other see the same old stuff: Newly trained Kool-Aid drinkers with a tiny bit-o-experience thinking that they have been taught by the only true master, and that only the masters word has value..... If I know all the tool, and I UNDERSTAND all the tools, Im still not trained at all And you were allso a newbie once - so give us some leeway. Actually strike that - you were probly never a newbie, but please give us some leeway anyway Quote: (Originally Posted by jradomski) Also remeber the student is taught that whenever possible switch to O2 and run it as an o2 rebreather starting at 6m... If you have O2 there is no reason to run SCR from this point on.. Yes, but the formula IMVHO is not very intuitive, and I really dont understand WHY it is taught, unless the student is also taught that it should not be used unless PO2 is above X..... My point was exactly that if O2 was not available then the student could try to use it, and without realising its limitations could become hypoxic. -------------------- I know I'm an annoying newbie, but I'm really learning from this so please put up with me BTW: anyone figure out why I drove my instructor (Rasmus) to the brink off insanity while doing my mod 1, hehe? Regards Nicolai __________________ Woohooo - I can change my rEvo! Its going to be bitchin' tricked out piece of gear Last edited by jradomski : 15th January 2008 at 16:39. Reason: added by request of author
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1st January 2008, 16:04	#65 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by Dsix36) I wanna take a shot at this one: Maintain minimum loop volumn by merely injecting O2 as the loop diminishes from O2 metabolism. My depth would have to remain reasonably consistant though. Did I win????? as long as the o2 is 100%.. if you are at a constant depth this works fine, but if you are changing depths SCR is a better choice.. This technique also has it problems if you are shallower than you were.. IE during deco.. SInce you are offgassing inert gas INTO the loop.. In this case frequent dil flushes (or a deco gas) with manual o2 addition could be used.. Lots of different techniques CAN be combined once each individual one is MASTERED and PRACTICED.. You use the best for what you have.. the 5:1 plus 1/atm is for simplicity (especially when metric).. As the persons skills and understanding grow, they can build on the foundation set in place.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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1st January 2008, 16:17	#66 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by HMC) Dave, how would your technique get me out of the predicament?. The short answer is that you don't know how to do it because it's not "in the book"... so you don't see the value to it. Maybe the only value is being able to write a longer good-bye letter to your wife! But I'm going to put off drowning as long as possible... and I'll be alive a lot longer than you are. These hypotheticals have more than practical value, so don't blow them off. At the very least they are an advanced intellectual concept to think about, because excercising your brain on things like this helps build the habits and knowlage that might be useful one day when you are confronted with a situation that you were not specifically trained to deal with. Back tomorrow late. Have fun with the regularly scheduled rant one and all. Dave . __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
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1st January 2008, 16:22	#67 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by Hanssing) I still think its overly complicated, and what youre after Dave (constant PO2 close to 0.18) That's not at all what I am looking for.... As a more desperate survival technique than the basic 5:1+atma SCC mode, I am asking you to use your brain to come up with a way to let the loop slide from whatever the raw diluent PP02 is after a full flush down to the point where it's no longer able to reliably maintain life, and then re-flush and let the cycle start again. It's a constantly varying PP02 survival mode... that's all. Figure it out and let me know when you're done. A "Diver Dave Seal of Approval" waits the successful calculation. It needs to be able to be done "in your head" while scared... I am NOT suggesting that this be anything other than an absolutely last-ditch method. If access to the surface is available, the 5:1+atma is going to be my choice as well. Really, it would be a bad day to even get that far. I just like every ace in the deck to be in my hand. Dave . __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 1st January 2008 at 16:26.
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1st January 2008, 16:32	#68 (permalink)
Hanssing flap-flop ..... flap-flop Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Denmark Posts: 430	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by Dave Sutton) I am asking you to use your brain to come up with a way to let the loop slide from whatever the raw diluent PP02 is after a full flush down to the point where it's no longer able to reliably maintain life, and then re-flush and let the cycle start again. It's a constantly varying PP02 survival mode... that's all. By constant PO2 i mean constant beforere each flush (PoTaToe...) We can also callit "constantly varying PP02", or constant average PO2.... (DIL_PPO-0.2)*B Good enough answer? Only thing is you need to measure B beforehand. __________________ Woohooo - I can change my rEvo! Its going to be bitchin' tricked out piece of gear
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1st January 2008, 16:37	#69 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: Deerfield Beach, Florida Posts: 1,154	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by HMC) hmmm... let us keep it simple... if you did that at 6 meters with O2 without doing ever a diluent flush... would you live or die? I would live at any depth. The PO2 would remain the same as when I began the procedure. PO2 could be calculated with dil at depth to know what it is after a loop flush also. Then just maintain with O2 injection, but this will only work when my depth doesn't change. __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
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1st January 2008, 16:41	#70 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: SCR/VSC as a CCR Bailout Method Quote: (Originally Posted by Hanssing) I clearly remember that debate, and I was thourougly told off by my instructor when discussing DIL-selections during my mod one. Also the cell-validation comes to mind. I however was told: Air or 10/50 as dil was the way to go..... Yes, but the formula IMVHO is not very intuitive, and I really dont understand WHY it is taught, unless the student is also taught that it should not be used unless PO2 is above X..... My point was exactly that if O2 was not available then the student could try to use it, and without realising its limitations could become hypoxic. Regards Nicolai Firts ANDI teaches to use the right diluent for the dive.. 10/50 for a 60m dive isnt optimal even at 100m Im using 13/50.. secondly the calculation is EASY for you metric folk.. move the decimal place one spot and you have how many breaths to add to 5.. even if someone was really narced they cound do this.. even using say 10/50 at 21m.. its still going to be a breathable gas at 7 breaths.. not that I would use it here.. My deco gas would be plugged in.. at 10m a 10/50 is a .20, if you aren;t working and have good technique, the lop should still be breathable.. Diluent selection and contingency planning should be part of every Mix class.. This becomes even more important once hypoxic mixes begin to be used.. If I was stuck at 10m with only a hypoxic dil and my offboard o2, I would do an approximate mix on the fly.. It can be done with practice and a bit of planning.. But here you need to know the ratio of a breath to dead gas space.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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