The Pelagian Way

Jonathan · 4th September 2007, 15:03

Quote: (Originally Posted by dantheman)

You have neither with certainty under any system.

DrMike is closest when he proposes a system with 4000 cells of varying characteristics . . .
even then the best we can say is that the odds are much better.

--dan

But I can't afford 4000 cells...
and besides very little in life is truly certain if anyone is going to follow that line. 3 gives a good idea. I'd not be comfortable with 2. A third plugged into a coputre to calculate deco - great. I'm still not convinced this is the best way to go. the deco regulating sensor could be the one to go in which case it's back to assumed set point deco. Voting logic across three when it's reliable. Of which anyone got experience of the Diamond voting box and HUD set up?

There is a degree of necessary care and then there is practicality in the available prep & kit up time and potential for missed and bailed dives owing to uncertainties. I like being in the water, and I like spending necessary time in the shed and pre dive, but prefer to keep it to the necessary, there's pints to be had!

Cheers,
J.

decoweenie · 4th September 2007, 15:10

Quote: (Originally Posted by OceanOpportunity)

...doing a dil check every few minutes may be distracting during a dive...

"Real life, part trois"

People don't even check their PO2 display every few minutes, much less doing a dil check.

Raise your hand if you buy a CCR to enjoy your diving more than OC, or if you want to spend most of your diving time checking your loop PO2!

Drmike · 4th September 2007, 15:18

Quote: (Originally Posted by decoweenie)

"Real life, part trois"

People don't even check their PO2 display every few minutes, much less doing a dil check.

Raise your hand if you buy a CCR to enjoy your diving more than OC, or if you want to spend most of your diving time checking your loop PO2!

yeh an RB80 is looking like such a good idea right now

Given how crap the cells are I honestly fully get why GUE are so against CCRs - and the lack of understanding about cell failures in the community just leaves me shaking my head.

decoweenie · 4th September 2007, 15:24

Quote: (Originally Posted by Drmike)

yeh an RB80 is looking like such a good idea right now

I don't believe you just said that...

Trust me (from the point of view of someone dived the PVR-BASC and EDO-04 in the past) that you don't want to go down that route.

Just think about what you just wrote on another thread about it is nice to have stupid-stage-monkeys setting the stages for your push dive, yo don't have that luxury, my friend!

Drmike · 4th September 2007, 15:27

Quote: (Originally Posted by decoweenie)

I don't believe you just said that...

Trust me (from the point of view of someone dived the PVR-BASC and EDO-04 in the past) that you don't want to go down that route.

Just think about what you just wrote on another thread about it is nice to have stupid-stage-monkeys setting the stages for your push dive, yo don't have that luxury, my friend!

Yup and thats the only reason Im not diving an RB80

Rebreatherlab · 4th September 2007, 15:46

Quote: (Originally Posted by Rebreatherlab)[IMG]file:///C:/DOCUME%7E1/Andy/LOCALS%7E1/Temp/msohtml1/01/clip_image001.gif[/IMG]
Andy: Seems you're missing the point. The point is that the ability to quickly and easily put some DIL across the cells is safer than not being able to do it.
Mike: what units dont allow this??
Andy: Most units out there does not inject DIL across the cell membranes.
Mike: Does the Palagian have an dil inject right next to the cells (I designed my BOB in same way) to enable fast verification?
Andy: It sure does. On all THREEEEE cells!

Andy: Sure it is better to have 3 than 2 cells and sure it is better to have 5 than 4 cells.
The Pelagian can use 3 cells, but they are split up in order to not share common ground or battery. The Pelagian is not sold with a third read out in its basic package as many divers would prefer to run a live deco computer from one cell. If not, an additional display can be added.
Mike: this was my understanding when we talked at adex and I fully agree with that philophosy. Indeed a 2 cell display and a seperate 1 cell display is safer than a single 3 cell display and this is how I dived my BOB previously.
Andy: If one argues that simply adding a third cell would be a better solution and think that you are safe just because 2 cells read one thing and ONLY one cell reads another you are just trying to improve your luck.
Mike: that statement makes little sense to me and to me is contradictory to your earlier one (the more the safer). Having had 2 cells fail together several times a 3rd cell is definately going to help as it may (in my cases did) show a variance.
Andy: OK. I have to be more clear here: What I mean is that if you are NOT flushing or making good use of available instant cell validation by putting small amounts of DIL across the cell faces at regular intervals and INSTEAD put your trust in the slightly better odds that two similar readings are right and a third different reading is wrong, then you are on your way to statistics. Is that making sense? In fact, here I will stand up and say with a loud and clear boy scout voice: Given the choice of diving a unit with three cells and no instant cell validation or a unit with only ONE cell with instant cell validation I would choose the latter any day, any dive. AND given the choice of two units WITH instant cell validation, one with one cell and the other with three or fifteen cells………..drum roll…….I would choose the one with most cells. Simply because dying cells are an inconvenience rather than a drama.
Andy: The corner stones are checking cells in air (or any other known gas) at 1 ATA, then in pure O2 at 1 ATA, then pure O2 at 6m, then reference the readouts frequently with DIL during the dive.
Mike: yes I agree those are good methods but how practical is doing dil flushes at depth?
Andy: Extremely unpractical. Hence the instant cell validation which is easily done in 10 m intervals.
Mike: How often will people really do them (damn we cant even check our displays often enough)
Andy: I would say rarely. Most likely because it usually requires quite a bit of DIL at depth, takes time and screws up the loop mix.
Mike: With 3 cells I dont think theres such a need to do dil verifications.
Andy: I respectfully totally disagree. With this attitude you truly need much more than 3 cells to beat the odds time and time again!
Mike: I also dont want to (and quite frankly probably couldnt) calculate the dil ppo2 at all depths on deep dives anyway
Andy: Try some more helium in the mix, an evening class in maths or both!
Andy: Sorry I am tired...
Mike: Sorry for what?
Andy: Just thought it came out a bit harsh, that’s all.

Drmike · 4th September 2007, 16:48

Quote:

Andy:

Quote:

OK. I have to be more clear here: What I mean is that if you are NOT flushing or making good use of available instant cell validation by putting small amounts of DIL across the cell faces at regular intervals and INSTEAD put your trust in the slightly better odds that two similar readings are right and a third different reading is wrong, then you are on your way to statistics.

Not meaning to be argumentative but Im not sure of your comparing apples with apples in your eg above

Compare 2 cells with instant cell verification to 3 cells that you dil flush when they show up that there is any variance...

Instant cell verification is just a fast dil flush - something thats taught on every ccr course as something you do if you have cell variances in a 3 cell system.

I agree if your not dil flushing to verify when a 3 cell system gives a variance that this isnt as safe as 2 cells that your are verifyijng - but who wouldnt flush in that situation??? it is SOP. (or at least its supposed to be )

Anyone can do a dil flush on any unit - maybe not as fast as on your - but it can be done - and is done. It would be cool if ot could be done faster as you seem to have set up - a good idea,

As for calculating ppo2 easily at deep depths -i pressume your joking re additional helium. N2 is only part of the dumbifying effect and personally after a fast descent even on heliox Im as thick as pig sh1t sub 150m

and deep = helium and thats where Im working hard and is therefore (He and exersion being high trigger to tox) where Im most concerned about too high O2 so deep is where Id want to flush (if I was diving a 2 cell system) = lots of dil (ordinarily)

My bob had fast cell verification for just the reason yours does - but I had 3 cells and would only flush if there was a variance as Im as thick as pig sh1t and too busy trying to do the dive

.

I guess thats one way to look at it:
whats safer (jn all aspects) : 2 cells with instant flush or 3 cells which if they show any variance can be instant flushed? Hmm I may have to mod the RAT to give fast verification.....

I agree there is a lot to be said for flushing cells at depth at intervals - regardless of what number of cells one is using and having a fast way to do that is a neat advantage - do you think this could help clear water off cell faces - I recall years ago the 'puffer' was tried

Marc T · 4th September 2007, 17:48

Quote: (Originally Posted by Drmike)

I recall years ago the 'puffer' was tried

Does somehone have a real experience with that, neither heard about that except on Dave Sutton website?
I read somewhere on a Rebreather World thread that its not good to flush directly on a sensor's face, any idea about that?

Rebreatherlab · 4th September 2007, 18:55

I am even more tired now due to sleep deprivation, but lets see

below)

Quote: (Originally Posted by Drmike)

Not meaning to be argumentative but Im not sure of your comparing apples with apples in your eg above

Compare 2 cells with instant cell verification to 3 cells that you dil flush when they show up that there is any variance...

Andy: Well I think the instant DIL validation is so important I actually do it many times during a dive even though all cells reads the same. I have killed 3 cells on same dive in the same moment a few times, so I am very cautious and very alive. To compare: yes I agree the three cell system that you ACTUALLY DIL flush as many times as I validate is the same thing, but very unpractical due to the amount of wasted DIL and jumpy set point. Also consider that in order to get back to set point after a complete DIL flush in the shallows (assuming only one DIL) can easily create high Po2 spikes if you dont spend long time to build the set point back gradually. Coming up you might anyway have high CNS load and some times one breath of very high Po2 can push over the cliff. It is very interesting to see what such spikes can actually be on a simple (fast) Po2 display and that they never pick up on a slow responding ECCR hand set or VR3. Oups. drifting a bit...

Instant cell verification is just a fast dil flush - something thats taught on every ccr course as something you do if you have cell variances in a 3 cell system.

Andy: Yup. If you have lots and lots of DIL and time to kill you can do the same with any Rebreather. The number of cells is always better in the higher numbers. I am just saying I think it's crazy to only DIL flush or use instant cell validation only when cells disagree. In a Pelagian course we teach to grab every moment. Need to clear your mask? Check your cells when you inhale. Descending a bit? Check your cells etc. etc.

I agree if your not dil flushing to verify when a 3 cell system gives a variance that this isnt as safe as 2 cells that your are verifyijng - but who wouldnt flush in that situation??? it is SOP. (or at least its supposed to be )

Andy: Maybe a poll on this? I think people are mostly trained to DIL flush when cells disagree. Thing is that DIL flushes tends to play havoc with set point controllers. With MCCR this is not an issue and since the instant cell vaildation is hands free (ADV triggered) it is just a half breath through the nose and inhale slowly. Doesnt really drop the set point too much and also an easy way to check respond time in between cells, (forget VR3 as it is too slow to begin with).

Anyone can do a dil flush on any unit - maybe not as fast as on your - but it can be done - and is done. It would be cool if ot could be done faster as you seem to have set up - a good idea,

Andy: Yes isn't it! See above for my thoughts on why divers acutally do not flush frequently enough. If you had been diving a one cell system for 8 years that had instant cell validation I think you would see why validating the cell is just as important to read what it says. After all what is the point in reading something you dont know is accurate? Hold it. I am not saying it is better to have only one cell! Or actually it might be for the sake of drilling in the routine

As for calculating ppo2 easily at deep depths -i pressume your joking re additional helium. N2 is only part of the dumbifying effect and personally after a fast descent even on heliox Im as thick as pig sh1t sub 150m

and deep = helium and thats where Im working hard and is therefore (He and exersion being high trigger to tox) where Im most concerned about too high O2 so deep is where Id want to flush (if I was diving a 2 cell system) = lots of dil (ordinarily)

Andy: Yes a partial joke. You can not disagree that too cheap mixes gets you more narced. For sure fast descents+Co2 are huge factors. Still I tend to check the cells and do the math frequently. I may come crying back admitting I was wrong after a few challenging deeper dives. Lets see.

My bob had fast cell verification for just the reason yours does - but I had 3 cells and would only flush if there was a variance as Im as thick as pig sh1t and too busy trying to do the dive

.

Andy: Hr, hrm. My Rebreather usually has three cells in it but they all get validated even when they all agree. The real question is why your new RAT does not have it if your BOB had it? Did you have any reason not to have it inthe RAT?

I guess thats one way to look at it:
whats safer (jn all aspects) : 2 cells with instant flush or 3 cells which if they show any variance can be instant flushed? Hmm I may have to mod the RAT to give fast verification.....

Andy: Seeeen! The safest is to have three or more cells as isolated as possible and then validate them frequently and not succumb to a false sense of security just because three cells read the same. At least we can agree that cells are shitty and should not be trusted.

I agree there is a lot to be said for flushing cells at depth at intervals - regardless of what number of cells one is using and having a fast way to do that is a neat advantage - do you think this could help clear water off cell faces - I recall years ago the 'puffer' was tried

Andy: With the Pelagian you inhale slowly to validate and inhale forcefully to clear water off the cells. Takes some trial and error to get the nozzle holes just right. The important thing is to make sure the Dil nozzle is not facing the cells head on like on the Cis Lunar as it tends to drive water through the HP membrane and screw the cells for a week!

So, can we kiss and be freinds now?

Andy

Drmike · 5th September 2007, 04:54

Thanks for you reply Andy,

Quote:

Andy: Hr, hrm. My Rebreather usually has three cells in it but they all get validated even when they all agree. The real question is why your new RAT does not have it if your BOB had it? Did you have any reason not to have it inthe RAT?

I built the BOB for one purpose (To do the deep cave Sra Keow - we had planned on max depth 280m) so was aware that flushing at depth to validate cells would quickly kill off my dil supply. It was a relaively untested bit of kit* I was using an unfamilar ppo2 display and an unfamilar (untested) VR3 display so wanted the option to validate at depth at intervals (assuming Id bailed to it) if displays started to show variance or not (10 hours is a long time to be breathing the wrong ppo2). On the RAT I am using familar componenst and well tested (plus not taking it to 280m) so just thought Id make do with normal dil flush method.

I think your idea makes good sense- I like the idea of using a tiny amount of dil to do a very quick validation with the press of a button. The faster, easier the validation and the less dil it uses - the more sense it makes..hmmm I feel a mod coming on. Of course this would only work easily on a mCCR - but I do like it.

Quote:

So, can we kiss and be freinds now?

did we stop being friends?

* Which is why I had full OC bail out as well

.

4th September 2007, 15:03	#41 (permalink)
Jonathan New Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Sep 2005 Location: Ireland Posts: 28	Re: The Pelagian Way Quote: (Originally Posted by dantheman) You have neither with certainty under any system. DrMike is closest when he proposes a system with 4000 cells of varying characteristics . . . even then the best we can say is that the odds are much better. --dan But I can't afford 4000 cells... and besides very little in life is truly certain if anyone is going to follow that line. 3 gives a good idea. I'd not be comfortable with 2. A third plugged into a coputre to calculate deco - great. I'm still not convinced this is the best way to go. the deco regulating sensor could be the one to go in which case it's back to assumed set point deco. Voting logic across three when it's reliable. Of which anyone got experience of the Diamond voting box and HUD set up? There is a degree of necessary care and then there is practicality in the available prep & kit up time and potential for missed and bailed dives owing to uncertainties. I like being in the water, and I like spending necessary time in the shed and pre dive, but prefer to keep it to the necessary, there's pints to be had! Cheers, J.
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4th September 2007, 15:10	#42 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,509	Re: The Pelagian Way Quote: (Originally Posted by OceanOpportunity) ...doing a dil check every few minutes may be distracting during a dive... "Real life, part trois" People don't even check their PO2 display every few minutes, much less doing a dil check. Raise your hand if you buy a CCR to enjoy your diving more than OC, or if you want to spend most of your diving time checking your loop PO2! __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
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4th September 2007, 15:18	#43 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,062	Re: The Pelagian Way Quote: (Originally Posted by decoweenie) "Real life, part trois" People don't even check their PO2 display every few minutes, much less doing a dil check. Raise your hand if you buy a CCR to enjoy your diving more than OC, or if you want to spend most of your diving time checking your loop PO2! yeh an RB80 is looking like such a good idea right now Given how crap the cells are I honestly fully get why GUE are so against CCRs - and the lack of understanding about cell failures in the community just leaves me shaking my head. __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
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4th September 2007, 15:24	#44 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,509	Re: The Pelagian Way Quote: (Originally Posted by Drmike) yeh an RB80 is looking like such a good idea right now I don't believe you just said that... Trust me (from the point of view of someone dived the PVR-BASC and EDO-04 in the past) that you don't want to go down that route. Just think about what you just wrote on another thread about it is nice to have stupid-stage-monkeys setting the stages for your push dive, yo don't have that luxury, my friend! __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
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4th September 2007, 15:27	#45 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,062	Re: The Pelagian Way Quote: (Originally Posted by decoweenie) I don't believe you just said that... Trust me (from the point of view of someone dived the PVR-BASC and EDO-04 in the past) that you don't want to go down that route. Just think about what you just wrote on another thread about it is nice to have stupid-stage-monkeys setting the stages for your push dive, yo don't have that luxury, my friend! Yup and thats the only reason Im not diving an RB80 __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
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4th September 2007, 15:46	#46 (permalink)
Rebreatherlab RebreatherWorld Sponsor Current Rebreather/s: Pelagian Other Rebreather/s: Not Bought Yet Classic Kiss Pelagian Join Date: Sep 2005 Location: Thailand Posts: 193	Re: The Pelagian Way Quote: (Originally Posted by Rebreatherlab)[IMG]file:///C:/DOCUME%7E1/Andy/LOCALS%7E1/Temp/msohtml1/01/clip_image001.gif[/IMG] Andy: Seems you're missing the point. The point is that the ability to quickly and easily put some DIL across the cells is safer than not being able to do it. Mike: what units dont allow this?? Andy: Most units out there does not inject DIL across the cell membranes. Mike: Does the Palagian have an dil inject right next to the cells (I designed my BOB in same way) to enable fast verification? Andy: It sure does. On all THREEEEE cells! Andy: Sure it is better to have 3 than 2 cells and sure it is better to have 5 than 4 cells. The Pelagian can use 3 cells, but they are split up in order to not share common ground or battery. The Pelagian is not sold with a third read out in its basic package as many divers would prefer to run a live deco computer from one cell. If not, an additional display can be added. Mike: this was my understanding when we talked at adex and I fully agree with that philophosy. Indeed a 2 cell display and a seperate 1 cell display is safer than a single 3 cell display and this is how I dived my BOB previously. Andy: If one argues that simply adding a third cell would be a better solution and think that you are safe just because 2 cells read one thing and ONLY one cell reads another you are just trying to improve your luck. Mike: that statement makes little sense to me and to me is contradictory to your earlier one (the more the safer). Having had 2 cells fail together several times a 3rd cell is definately going to help as it may (in my cases did) show a variance. Andy: OK. I have to be more clear here: What I mean is that if you are NOT flushing or making good use of available instant cell validation by putting small amounts of DIL across the cell faces at regular intervals and INSTEAD put your trust in the slightly better odds that two similar readings are right and a third different reading is wrong, then you are on your way to statistics. Is that making sense? In fact, here I will stand up and say with a loud and clear boy scout voice: Given the choice of diving a unit with three cells and no instant cell validation or a unit with only ONE cell with instant cell validation I would choose the latter any day, any dive. AND given the choice of two units WITH instant cell validation, one with one cell and the other with three or fifteen cells………..drum roll…….I would choose the one with most cells. Simply because dying cells are an inconvenience rather than a drama. Andy: The corner stones are checking cells in air (or any other known gas) at 1 ATA, then in pure O2 at 1 ATA, then pure O2 at 6m, then reference the readouts frequently with DIL during the dive. Mike: yes I agree those are good methods but how practical is doing dil flushes at depth? Andy: Extremely unpractical. Hence the instant cell validation which is easily done in 10 m intervals. Mike: How often will people really do them (damn we cant even check our displays often enough) Andy: I would say rarely. Most likely because it usually requires quite a bit of DIL at depth, takes time and screws up the loop mix. Mike: With 3 cells I dont think theres such a need to do dil verifications. Andy: I respectfully totally disagree. With this attitude you truly need much more than 3 cells to beat the odds time and time again! Mike: I also dont want to (and quite frankly probably couldnt) calculate the dil ppo2 at all depths on deep dives anyway Andy: Try some more helium in the mix, an evening class in maths or both! Andy: Sorry I am tired... Mike: Sorry for what? Andy: Just thought it came out a bit harsh, that’s all. __________________ www.rebreatherlab.com
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4th September 2007, 16:48	#47 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,062	Re: The Pelagian Way Quote: Andy: Quote: OK. I have to be more clear here: What I mean is that if you are NOT flushing or making good use of available instant cell validation by putting small amounts of DIL across the cell faces at regular intervals and INSTEAD put your trust in the slightly better odds that two similar readings are right and a third different reading is wrong, then you are on your way to statistics. Not meaning to be argumentative but Im not sure of your comparing apples with apples in your eg above Compare 2 cells with instant cell verification to 3 cells that you dil flush when they show up that there is any variance... Instant cell verification is just a fast dil flush - something thats taught on every ccr course as something you do if you have cell variances in a 3 cell system. I agree if your not dil flushing to verify when a 3 cell system gives a variance that this isnt as safe as 2 cells that your are verifyijng - but who wouldnt flush in that situation??? it is SOP. (or at least its supposed to be ) Anyone can do a dil flush on any unit - maybe not as fast as on your - but it can be done - and is done. It would be cool if ot could be done faster as you seem to have set up - a good idea, As for calculating ppo2 easily at deep depths -i pressume your joking re additional helium. N2 is only part of the dumbifying effect and personally after a fast descent even on heliox Im as thick as pig sh1t sub 150m and deep = helium and thats where Im working hard and is therefore (He and exersion being high trigger to tox) where Im most concerned about too high O2 so deep is where Id want to flush (if I was diving a 2 cell system) = lots of dil (ordinarily) My bob had fast cell verification for just the reason yours does - but I had 3 cells and would only flush if there was a variance as Im as thick as pig sh1t and too busy trying to do the dive . I guess thats one way to look at it: whats safer (jn all aspects) : 2 cells with instant flush or 3 cells which if they show any variance can be instant flushed? Hmm I may have to mod the RAT to give fast verification..... I agree there is a lot to be said for flushing cells at depth at intervals - regardless of what number of cells one is using and having a fast way to do that is a neat advantage - do you think this could help clear water off cell faces - I recall years ago the 'puffer' was tried __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you Last edited by Drmike : 4th September 2007 at 17:10.
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4th September 2007, 17:48	#48 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 433	Re: The Pelagian Way Quote: (Originally Posted by Drmike) I recall years ago the 'puffer' was tried Does somehone have a real experience with that, neither heard about that except on Dave Sutton website? I read somewhere on a Rebreather World thread that its not good to flush directly on a sensor's face, any idea about that?
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4th September 2007, 18:55	#49 (permalink)
Rebreatherlab RebreatherWorld Sponsor Current Rebreather/s: Pelagian Other Rebreather/s: Not Bought Yet Classic Kiss Pelagian Join Date: Sep 2005 Location: Thailand Posts: 193	Re: The Pelagian Way I am even more tired now due to sleep deprivation, but lets seebelow) Quote: (Originally Posted by Drmike) Not meaning to be argumentative but Im not sure of your comparing apples with apples in your eg above Compare 2 cells with instant cell verification to 3 cells that you dil flush when they show up that there is any variance... Andy: Well I think the instant DIL validation is so important I actually do it many times during a dive even though all cells reads the same. I have killed 3 cells on same dive in the same moment a few times, so I am very cautious and very alive. To compare: yes I agree the three cell system that you ACTUALLY DIL flush as many times as I validate is the same thing, but very unpractical due to the amount of wasted DIL and jumpy set point. Also consider that in order to get back to set point after a complete DIL flush in the shallows (assuming only one DIL) can easily create high Po2 spikes if you dont spend long time to build the set point back gradually. Coming up you might anyway have high CNS load and some times one breath of very high Po2 can push over the cliff. It is very interesting to see what such spikes can actually be on a simple (fast) Po2 display and that they never pick up on a slow responding ECCR hand set or VR3. Oups. drifting a bit... Instant cell verification is just a fast dil flush - something thats taught on every ccr course as something you do if you have cell variances in a 3 cell system. Andy: Yup. If you have lots and lots of DIL and time to kill you can do the same with any Rebreather. The number of cells is always better in the higher numbers. I am just saying I think it's crazy to only DIL flush or use instant cell validation only when cells disagree. In a Pelagian course we teach to grab every moment. Need to clear your mask? Check your cells when you inhale. Descending a bit? Check your cells etc. etc. I agree if your not dil flushing to verify when a 3 cell system gives a variance that this isnt as safe as 2 cells that your are verifyijng - but who wouldnt flush in that situation??? it is SOP. (or at least its supposed to be ) Andy: Maybe a poll on this? I think people are mostly trained to DIL flush when cells disagree. Thing is that DIL flushes tends to play havoc with set point controllers. With MCCR this is not an issue and since the instant cell vaildation is hands free (ADV triggered) it is just a half breath through the nose and inhale slowly. Doesnt really drop the set point too much and also an easy way to check respond time in between cells, (forget VR3 as it is too slow to begin with). Anyone can do a dil flush on any unit - maybe not as fast as on your - but it can be done - and is done. It would be cool if ot could be done faster as you seem to have set up - a good idea, Andy: Yes isn't it! See above for my thoughts on why divers acutally do not flush frequently enough. If you had been diving a one cell system for 8 years that had instant cell validation I think you would see why validating the cell is just as important to read what it says. After all what is the point in reading something you dont know is accurate? Hold it. I am not saying it is better to have only one cell! Or actually it might be for the sake of drilling in the routine As for calculating ppo2 easily at deep depths -i pressume your joking re additional helium. N2 is only part of the dumbifying effect and personally after a fast descent even on heliox Im as thick as pig sh1t sub 150m and deep = helium and thats where Im working hard and is therefore (He and exersion being high trigger to tox) where Im most concerned about too high O2 so deep is where Id want to flush (if I was diving a 2 cell system) = lots of dil (ordinarily) Andy: Yes a partial joke. You can not disagree that too cheap mixes gets you more narced. For sure fast descents+Co2 are huge factors. Still I tend to check the cells and do the math frequently. I may come crying back admitting I was wrong after a few challenging deeper dives. Lets see. My bob had fast cell verification for just the reason yours does - but I had 3 cells and would only flush if there was a variance as Im as thick as pig sh1t and too busy trying to do the dive . Andy: Hr, hrm. My Rebreather usually has three cells in it but they all get validated even when they all agree. The real question is why your new RAT does not have it if your BOB had it? Did you have any reason not to have it inthe RAT? I guess thats one way to look at it: whats safer (jn all aspects) : 2 cells with instant flush or 3 cells which if they show any variance can be instant flushed? Hmm I may have to mod the RAT to give fast verification..... Andy: Seeeen! The safest is to have three or more cells as isolated as possible and then validate them frequently and not succumb to a false sense of security just because three cells read the same. At least we can agree that cells are shitty and should not be trusted. I agree there is a lot to be said for flushing cells at depth at intervals - regardless of what number of cells one is using and having a fast way to do that is a neat advantage - do you think this could help clear water off cell faces - I recall years ago the 'puffer' was tried Andy: With the Pelagian you inhale slowly to validate and inhale forcefully to clear water off the cells. Takes some trial and error to get the nozzle holes just right. The important thing is to make sure the Dil nozzle is not facing the cells head on like on the Cis Lunar as it tends to drive water through the HP membrane and screw the cells for a week! So, can we kiss and be freinds now? Andy __________________ www.rebreatherlab.com
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5th September 2007, 04:54	#50 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,062	Re: The Pelagian Way Thanks for you reply Andy, Quote: Andy: Hr, hrm. My Rebreather usually has three cells in it but they all get validated even when they all agree. The real question is why your new RAT does not have it if your BOB had it? Did you have any reason not to have it inthe RAT? I built the BOB for one purpose (To do the deep cave Sra Keow - we had planned on max depth 280m) so was aware that flushing at depth to validate cells would quickly kill off my dil supply. It was a relaively untested bit of kit* I was using an unfamilar ppo2 display and an unfamilar (untested) VR3 display so wanted the option to validate at depth at intervals (assuming Id bailed to it) if displays started to show variance or not (10 hours is a long time to be breathing the wrong ppo2). On the RAT I am using familar componenst and well tested (plus not taking it to 280m) so just thought Id make do with normal dil flush method. I think your idea makes good sense- I like the idea of using a tiny amount of dil to do a very quick validation with the press of a button. The faster, easier the validation and the less dil it uses - the more sense it makes..hmmm I feel a mod coming on. Of course this would only work easily on a mCCR - but I do like it. Quote: So, can we kiss and be freinds now? did we stop being friends? * Which is why I had full OC bail out as well . __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you Last edited by Drmike : 5th September 2007 at 05:01.
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