SCR/VSC as a CCR Bailout Method

***jradomski*** · 1st January 2008, 11:50

Quote: (Originally Posted by Hanssing)

OK, I'm now getting confused

Can people tell me if all the SCR-methods are full loop-purges or single breadth exhale? I naturally allways assumed single breath exhale.

Anyway, I then dont see the formula as providing constant FO2. It may provide an FO2 close to the used gas, but according to simple SCR-teory its not a "constant" FO2. In fact the FO2 will be dropping when depth descreases. SO I "kinda" call bullshit.....

I write kinda because noone have told me I'm wrong in my posts, and I have a hard time seeing where I'm wrong - but I have no reallife experience, so I'm not trusting my own logic completely......

Could someone please read my posts again and tell me what I am missing:
http://www.rebreatherworld.com/rebre...tml#post159529

To Dave S:
Based upon my no doubt flawed logic, and a SCR-methos thats NOT full loop purge, ie. oply normal exhale from loop. And uses the gas down to 0.16PPO
A simple 3-year old formula for how many breaths would be:
Figure out how many time you could rebreathe the gas at surface.
Normally the FO2 drops app. 4-5% pr. breath, and we can breathe 16%.
So air could be rebreathed 2 times at surface.
EAN26 could be rebreathed 3 times at surface.
etc.
Now scale that to absolute pressure, at do that SCR-rate:
So trapped at 30msw (4 ATM) with a HOT EAN30:
Max SCR-rate @ 4ATM = 4*4:1 = 16:1

Again based upon simple formulas from active-SCR theory we all know.

I'm must be so wrong it silly

I'm sadly looking out at snow falling, but this debate has really made me go out and do some SCr-training - and I'll use my own simplified formulas.....

Nicolai

PS: Attched the SCR-calculations I made the other day.

The method described above does work.. If you had to stay really long at any stop depth, the po2 would drop below what you expected but its still fairly close to the target, especially when deeper.. (The single extra breath was chosen so you do get a benefit from being deeper, and stay closer to the target without having to do complete flushes - IE save gas when deep to stay close to the po2 of what the oc gas would be).. I rather error on the side of caution (and I really don;t want to have to get into the math and figuring out each students dead/flush gas ratio)..

When You work it correctly the last and first breaths are larger than the other breaths so you get a better gas flush (the dead air to flush ratio is smaller).. also during the program its recommended that whenever you change a stop depth, a more throrough flush should be performed so that you know at all times what you are starting with.. Even without these extra precautions the loop is more than capable of sustaining life.. Small changes in po2 really isnt a worry... and since the loop is still functional, you would be switching to a pure o2 rebreather at 6m and 3m (but planning it for less) so your chance of DCS is reduced significantly.. The idea is to give the person a reasonable expectation of getting out of things either uninjured or with a treatable condition.. The simpler you make it the greater the liklihood of a positive outcome..

Rember we can UNBEND smeone but we can't undead someone..

***jradomski*** · 1st January 2008, 11:52

Quote: (Originally Posted by richie)

if you are running minimum loop volume you should only have a single breath to exhale

Thats the best use of gas but the worse for keeping the po2 close to that of the gasmix.. (highest dead air to refresh ratio - This varies by diver and by rebreather)

***jradomski*** · 1st January 2008, 11:59

Quote: (Originally Posted by HMC)

Joe, from your posts and your manual (which I have not read, but I will purchase and read) you should be complimented. I am actually thinking of doing some training with you at some stage as from your posts you seem to be an intelligent and good instructor (but for now I am already scheduled to do a DIRrebreather "Self-rescue" and DIRrebreather "Expedition Trimix" end of January in Thailand so a course with you will have to wait). Please do PM me your info. and detailed course info. and prices of what you offer and how I can purchase your manual.

Having said that, what you hinted back to in 2004 (unfortunately) has not been picked up by any other manual I read (i.e. see Mel's manual) and by any instructor I trained with, other than Cedric's which I think you will agree explains it very well in his manual.

WHen I wrote the "advanced ccr techniques manual" it was written specifically for the inspiration (last updated in 2005).. I never got around to the point where I was happy with it as a pubished work.. After I finish the HammerHead CCR manual, I intend on making the manual generic and expanding it..
The mnaual already goes into alot of detail about various survival techniques and loop composition (including lots on Helium usage)... I havent decided if I will do it as a downloadable PDF or make it an official ANDI manual.. Right now it only available to ANDI TECH CCR instructors.. and with my permission it can be distributed in paper form to someone taking a class with one of our instructors..

***jradomski*** · 1st January 2008, 12:02

Quote: (Originally Posted by HMC)

Either Joe or Cedrics' methods look pretty good to me.

The way I undestand it is you do not loop flush (unless loop gas is bad), but you exhale through your nose till you are on an empty loop (i.e. about 1.5 to 5 breaths). Then, when the loop is empty, you inhale just enough to fill your lungs pushing the manual addition dil. button and using the correct deco diluent for the depth (you need to be able to attach your BO bottles to you mnaul dil. inflator...). This is in-breath number 1.

Then, exhale and inhale (breath number 2), then exhale and inhale (breath number 3), then exhale and inhale (breath number 4), then exhale and inhale (breath number 5), then exhale through the nose and inhale with manul dil. injection.

If you use a low FO2 mix when shallow, it may kill you (but try it on land with air diluent and functioning electronics and a buddy to assist and pPO2 should not go below 18%).

Joe, am I getting it right (or am I doing 1 enhale too may)?

P.S. of course, the deeper you are the more breaths in accordance to Cedric or Joe's methodology.

The exact number of breaths is not critical +/-1 is not significant, shallow you would be using a richer mix anyway.. I teach to use 50% from 21m and shallower with a switch to 100% o2 at 6m (if available)..

Your description./technique is fine..

Hanssing · 1st January 2008, 12:41

Quote: (Originally Posted by jradomski)

Thats the best use of gas but the worse for keeping the po2 close to that of the gasmix.. (highest dead air to refresh ratio - This varies by diver and by rebreather)

Quote:

(and I really don;t want to have to get into the math and figuring out each students dead/flush gas ratio)..

Yes, and IMVHO thats the problem with the original described VSC-method. It works if you know the breath to loop ratio, and all your other parameters....

However the full loop-flush SCR-type has the distinct advantage, that it gives better avarage FO2 level. Ie. the end-level before each flush is the same weather you use single breath or full loop purge, but the full loop purge reaches FO2 nearly eaqual to the gas FO2, and the drops down, where as the single normal breath-purge keeps "constant" lower'ish FO2.
They do use the same amount of gas though....

There's however a important advantage to single breath purge strategy:
It is independant of loop-volume, independant of tidal-volume, and therefor in theory easier to do....
And its way easier to calculate the rate....

However the ratio: (Depth/10+5) will not give constant average PO2 when depth varies.
This would however: (5*(depth/10+1)) ..... But that assumes that you can do 5 breaths with a purged loop at surface. Wich is dependant of the GAS-used....

I still think the formula is wastefull at depth, and potentially dangerous near the surface. And no way will it keep "average" FO2 constant, when used at different depths.

Nicolai

Hanssing · 1st January 2008, 14:49

Quote: (Originally Posted by HMC)

Are you saying the Cedric and Joe methodology does not work?

Nope,

I have no doubt that if used with correct gasses (high FO2 for the depth) they work just fine. I however think they work fine for different reasons, and that constant 5 breath-cycle is dangerous unless the diver fully understands that this is based on a hot diluent for actual depth.

If used by a diver who bails out from say 40msw with no O2 or PPO-monitoring to Nitrox-classic (Air) and uses this formula all the way to 3msw the FO2 off the loop wont be +19% and it could become dangerous.....

Cant wait to test this myself. And ohhh boy will I have to eat a lot of humble-pie when I prove myself wrong

Nicolai

***jradomski*** · 1st January 2008, 15:11

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...).

I think you can go down 16% pPO2 and live quite happily therafter, and depending on your metabolism, as low as 12% pPO2 (but if you are working hard or moderately, at 12% FO2 you are probably dead).

HOWEVER, USE YOUR NITROX 50 FROM 21 METERS AND UP!!!

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)

**Dave Sutton** · 1st January 2008, 15:12

Quote: (Originally Posted by jradomski)

Remember we can UNBEND smeone but we can't undead someone..

Quote of the year Joe! Pulled it out at the last second, but.... well, you're a Yankees fan so.....

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.

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..... just an observation, but all that is new to them is old stuff to many others. Start reading the NWD archives... it's all been hashed out 10 years ago.

Off to go teach today, open water rebreather training dives, in Massachusetts, in January. Ya-Hoo! Figure sea temperature will be.... well, let's just say that it'll be cold. Think the 7 mm Unisuit needs to be tossed into the truck. Joe's scooter too!

Dave

.

***jradomski*** · 1st January 2008, 15:13

Quote: (Originally Posted by Hanssing)

If used by a diver who bails out from say 40msw with no O2 or PPO-monitoring to Nitrox-classic (Air) and uses this formula all the way to 3msw the FO2 off the loop wont be +19% and it could become dangerous.....

Cant wait to test this myself. And ohhh boy will I have to eat a lot of humble-pie when I prove myself wrong

Nicolai

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..

**Dave Sutton** · 1st January 2008, 15:26

Quote: (Originally Posted by HMC)

I understand the tools Cedric and Joe are giving me when it come to SCR bail-out, but I got no clue what Dave Sutton is rambling about.

That's the entire point: You don't know... and you seem to be unwilling to be taught.
Your depth of knowlage is just scratching the surface here and you're neither contributing, nor learning.

But: There's hope, and so here's a homework assignment for you: Figure out a way to flush you loop with diluent "X" at depth "Y" and then *staying there* as though you were trapped on the bottom and not sure you were going to find your way outta the (cave, wreck, etc) breath the gas until the loop falls to 0.20 PPO2. When you have this sorted you'll have a second HUGELY valuable survival tool. It might keep you alive in that "holy cow, I'm stuck in the electrical cables, I wish I had not tried for Doria-China like the Captain told me to" scenario until you either (A) are freed or (B) finally die.... Bottom line at this point is that I could give a crap about maintaining my loop PP02 "0.2 less than the F02 of the diluent at the surface"..... You can go back to that once you get cleared and start ascent.

(1): Figure out how to do this DILUENT ONLY.

(2): Then figure out a non-electronic way to do it USING 02.

(3): Then figure out how to do it (non electronic) using 02 until it's exhausted, then go to diuent only until it's exhausted.

If you can do all of this, then you can stay alive *a long time* while trapped. At least an order of magnitude longer than "5 breaths and a vent". That 5:1 plus ATMA is kids stuff... basic Level 1 knowlage. And we had to *drag* that outta you, since you though it was somehow "Holy Grail" information. It's, what... dive 3 on a Level 1 ANDI course Joe?

Go ahead: Impress me. I know how to do the above matrix... do you? Or, here's a challenge: Bring $1000 and yourself here, we'll take identical rebreathers, go to a platform in the quarry, turn off our electonics, and the last man outta the water takes all. My bet is that I'd be there another hour after you were sitting on the edge wondering what I was doing. Suggest that we each have a PP02 monitor that we cannot see, but that our safety diver can watch so we don't die. Game? Heck, let's make it better: Winner keeps the other guys rig too...

(maybe I should write a book....

)

Dave

.

1st January 2008, 11:50	#51 (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) OK, I'm now getting confused Can people tell me if all the SCR-methods are full loop-purges or single breadth exhale? I naturally allways assumed single breath exhale. Anyway, I then dont see the formula as providing constant FO2. It may provide an FO2 close to the used gas, but according to simple SCR-teory its not a "constant" FO2. In fact the FO2 will be dropping when depth descreases. SO I "kinda" call bullshit..... I write kinda because noone have told me I'm wrong in my posts, and I have a hard time seeing where I'm wrong - but I have no reallife experience, so I'm not trusting my own logic completely...... Could someone please read my posts again and tell me what I am missing: http://www.rebreatherworld.com/rebre...tml#post159529 To Dave S: Based upon my no doubt flawed logic, and a SCR-methos thats NOT full loop purge, ie. oply normal exhale from loop. And uses the gas down to 0.16PPO A simple 3-year old formula for how many breaths would be: Figure out how many time you could rebreathe the gas at surface. Normally the FO2 drops app. 4-5% pr. breath, and we can breathe 16%. So air could be rebreathed 2 times at surface. EAN26 could be rebreathed 3 times at surface. etc. Now scale that to absolute pressure, at do that SCR-rate: So trapped at 30msw (4 ATM) with a HOT EAN30: Max SCR-rate @ 4ATM = 44:1 = 16:1 Again based upon simple formulas from active-SCR theory we all know. I'm must be so wrong it silly I'm sadly looking out at snow falling, but this debate has really made me go out and do some SCr-training - and I'll use my own simplified formulas..... Nicolai PS: Attched the SCR-calculations I made the other day. The method described above does work.. If you had to stay really long at any stop depth, the po2 would drop below what you expected but its still fairly close to the target, especially when deeper.. (The single extra breath was chosen so you do get a benefit from being deeper, and stay closer to the target without having to do complete flushes - IE save gas when deep to stay close to the po2 of what the oc gas would be).. I rather error on the side of caution (and I really don;t want to have to get into the math and figuring out each students dead/flush gas ratio).. When You work it correctly the last and first breaths are larger than the other breaths so you get a better gas flush (the dead air to flush ratio is smaller).. also during the program its recommended that whenever you change a stop depth, a more throrough flush should be performed so that you know at all times what you are starting with.. Even without these extra precautions the loop is more than capable of sustaining life.. Small changes in po2 really isnt a worry... and since the loop is still functional, you would be switching to a pure o2 rebreather at 6m and 3m (but planning it for less) so your chance of DCS is reduced significantly.. The idea is to give the person a reasonable expectation of getting out of things either uninjured or with a treatable condition.. The simpler you make it the greater the liklihood of a positive outcome.. Rember we can UNBEND smeone but we can't undead someone.. __________________ 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. Last edited by jradomski : 1st January 2008 at 12:08.
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1st January 2008, 11:52	#52 (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 richie) if you are running minimum loop volume you should only have a single breath to exhale Thats the best use of gas but the worse for keeping the po2 close to that of the gasmix.. (highest dead air to refresh ratio - This varies by diver and by rebreather) __________________ 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, 11:59	#53 (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 HMC) Joe, from your posts and your manual (which I have not read, but I will purchase and read) you should be complimented. I am actually thinking of doing some training with you at some stage as from your posts you seem to be an intelligent and good instructor (but for now I am already scheduled to do a DIRrebreather "Self-rescue" and DIRrebreather "Expedition Trimix" end of January in Thailand so a course with you will have to wait). Please do PM me your info. and detailed course info. and prices of what you offer and how I can purchase your manual. Having said that, what you hinted back to in 2004 (unfortunately) has not been picked up by any other manual I read (i.e. see Mel's manual) and by any instructor I trained with, other than Cedric's which I think you will agree explains it very well in his manual. WHen I wrote the "advanced ccr techniques manual" it was written specifically for the inspiration (last updated in 2005).. I never got around to the point where I was happy with it as a pubished work.. After I finish the HammerHead CCR manual, I intend on making the manual generic and expanding it.. The mnaual already goes into alot of detail about various survival techniques and loop composition (including lots on Helium usage)... I havent decided if I will do it as a downloadable PDF or make it an official ANDI manual.. Right now it only available to ANDI TECH CCR instructors.. and with my permission it can be distributed in paper form to someone taking a class with one of our instructors.. __________________ 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, 12:02	#54 (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 HMC) Either Joe or Cedrics' methods look pretty good to me. The way I undestand it is you do not loop flush (unless loop gas is bad), but you exhale through your nose till you are on an empty loop (i.e. about 1.5 to 5 breaths). Then, when the loop is empty, you inhale just enough to fill your lungs pushing the manual addition dil. button and using the correct deco diluent for the depth (you need to be able to attach your BO bottles to you mnaul dil. inflator...). This is in-breath number 1. Then, exhale and inhale (breath number 2), then exhale and inhale (breath number 3), then exhale and inhale (breath number 4), then exhale and inhale (breath number 5), then exhale through the nose and inhale with manul dil. injection. If you use a low FO2 mix when shallow, it may kill you (but try it on land with air diluent and functioning electronics and a buddy to assist and pPO2 should not go below 18%). Joe, am I getting it right (or am I doing 1 enhale too may)? P.S. of course, the deeper you are the more breaths in accordance to Cedric or Joe's methodology. The exact number of breaths is not critical +/-1 is not significant, shallow you would be using a richer mix anyway.. I teach to use 50% from 21m and shallower with a switch to 100% o2 at 6m (if available).. Your description./technique is fine.. __________________ 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, 12:41	#55 (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 jradomski) Thats the best use of gas but the worse for keeping the po2 close to that of the gasmix.. (highest dead air to refresh ratio - This varies by diver and by rebreather) Quote: (and I really don;t want to have to get into the math and figuring out each students dead/flush gas ratio).. Yes, and IMVHO thats the problem with the original described VSC-method. It works if you know the breath to loop ratio, and all your other parameters.... However the full loop-flush SCR-type has the distinct advantage, that it gives better avarage FO2 level. Ie. the end-level before each flush is the same weather you use single breath or full loop purge, but the full loop purge reaches FO2 nearly eaqual to the gas FO2, and the drops down, where as the single normal breath-purge keeps "constant" lower'ish FO2. They do use the same amount of gas though.... There's however a important advantage to single breath purge strategy: It is independant of loop-volume, independant of tidal-volume, and therefor in theory easier to do.... And its way easier to calculate the rate.... However the ratio: (Depth/10+5) will not give constant average PO2 when depth varies. This would however: (5(depth/10+1)) ..... But that assumes that you can do 5 breaths with a purged loop at surface. Wich is dependant of the GAS-used.... I still think the formula is wastefull at depth, and potentially dangerous near the surface. And no way will it keep "average" FO2 constant, when used at different depths. Nicolai __________________ Woohooo - I can change my rEvo! Its going to be bitchin' tricked out piece of gear Last edited by Hanssing : 1st January 2008 at 12:52. Reason: Added some words missing in sentences.*
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1st January 2008, 14:49	#56 (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) Are you saying the Cedric and Joe methodology does not work? Nope, I have no doubt that if used with correct gasses (high FO2 for the depth) they work just fine. I however think they work fine for different reasons, and that constant 5 breath-cycle is dangerous unless the diver fully understands that this is based on a hot diluent for actual depth. If used by a diver who bails out from say 40msw with no O2 or PPO-monitoring to Nitrox-classic (Air) and uses this formula all the way to 3msw the FO2 off the loop wont be +19% and it could become dangerous..... Cant wait to test this myself. And ohhh boy will I have to eat a lot of humble-pie when I prove myself wrong Nicolai __________________ Woohooo - I can change my rEvo! Its going to be bitchin' tricked out piece of gear
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1st January 2008, 15:11	#57 (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 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...). I think you can go down 16% pPO2 and live quite happily therafter, and depending on your metabolism, as low as 12% pPO2 (but if you are working hard or moderately, at 12% FO2 you are probably dead). HOWEVER, USE YOUR NITROX 50 FROM 21 METERS AND UP!!! 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) __________________ 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, 15:12	#58 (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) Remember we can UNBEND smeone but we can't undead someone.. Quote of the year Joe! Pulled it out at the last second, but.... well, you're a Yankees fan so..... 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. 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..... just an observation, but all that is new to them is old stuff to many others. Start reading the NWD archives... it's all been hashed out 10 years ago. Off to go teach today, open water rebreather training dives, in Massachusetts, in January. Ya-Hoo! Figure sea temperature will be.... well, let's just say that it'll be cold. Think the 7 mm Unisuit needs to be tossed into the truck. Joe's scooter too! Dave . __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 1st January 2008 at 15:21.
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1st January 2008, 15:13	#59 (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) If used by a diver who bails out from say 40msw with no O2 or PPO-monitoring to Nitrox-classic (Air) and uses this formula all the way to 3msw the FO2 off the loop wont be +19% and it could become dangerous..... Cant wait to test this myself. And ohhh boy will I have to eat a lot of humble-pie when I prove myself wrong Nicolai 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.. __________________ 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, 15:26	#60 (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) I understand the tools Cedric and Joe are giving me when it come to SCR bail-out, but I got no clue what Dave Sutton is rambling about. That's the entire point: You don't know... and you seem to be unwilling to be taught. Your depth of knowlage is just scratching the surface here and you're neither contributing, nor learning. But: There's hope, and so here's a homework assignment for you: Figure out a way to flush you loop with diluent "X" at depth "Y" and then staying there as though you were trapped on the bottom and not sure you were going to find your way outta the (cave, wreck, etc) breath the gas until the loop falls to 0.20 PPO2. When you have this sorted you'll have a second HUGELY valuable survival tool. It might keep you alive in that "holy cow, I'm stuck in the electrical cables, I wish I had not tried for Doria-China like the Captain told me to" scenario until you either (A) are freed or (B) finally die.... Bottom line at this point is that I could give a crap about maintaining my loop PP02 "0.2 less than the F02 of the diluent at the surface"..... You can go back to that once you get cleared and start ascent. (1): Figure out how to do this DILUENT ONLY. (2): Then figure out a non-electronic way to do it USING 02. (3): Then figure out how to do it (non electronic) using 02 until it's exhausted, then go to diuent only until it's exhausted. If you can do all of this, then you can stay alive a long time while trapped. At least an order of magnitude longer than "5 breaths and a vent". That 5:1 plus ATMA is kids stuff... basic Level 1 knowlage. And we had to drag that outta you, since you though it was somehow "Holy Grail" information. It's, what... dive 3 on a Level 1 ANDI course Joe? Go ahead: Impress me. I know how to do the above matrix... do you? Or, here's a challenge: Bring $1000 and yourself here, we'll take identical rebreathers, go to a platform in the quarry, turn off our electonics, and the last man outta the water takes all. My bet is that I'd be there another hour after you were sitting on the edge wondering what I was doing. Suggest that we each have a PP02 monitor that we cannot see, but that our safety diver can watch so we don't die. Game? Heck, let's make it better: Winner keeps the other guys rig too... (maybe I should write a book.... ) Dave . __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 1st January 2008 at 16:00.
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