Cell Linearity

***Decodiver*** · 18th November 2006, 20:50

This is a new thread started on behalf and upon request of Martin:

Quote: (Originally Posted by dive2dive2000)

I dive a PRISM and the Unit will not calibrate unless you have 3 working senors and 98.3% or higher O2

One of my pre dive protocols (within 24hrs) is a mv check

If an O2 sensor is producing the proper mv out put can it still fail and not read over 1.6????

I personally believe sometimes less gadgets are better, and there are no shortcuts to ccr diving. If you do a mv check and a elevated PPO2 decent to 9m or a pressure pot test Murphy can still KILL you.

SHAME on any ccr diver who dosnt own a volt meter(it was required for my PRISM Training).

colinicky · 18th November 2006, 21:09

Well I must admit that I was taught absolutely nothing about checking cells on my Mod 1 Inspiration course & only learnt last week about checking the mv output .I was also told not to take the O2 above 1.6 at all ! Unfortunately not having dived with any ccr divers on a regular basis I didn't pick this up earlier

dave t · 18th November 2006, 21:30

this is what I teach on a mod 1 course

theory
cell construction
cell lifetime and why it has one
cell liniarity and how to check
when should I change my cells (pros and cons )
should I change all at once or one at a time (pros and cons )
why its best to use a certain brand of cell (or not) response time ect
how to read the date codes on telydyne cells
what milivolts are and should/shouldnt check them!

practical

how to fit and replace cells
how to check milivolts
how to calibrate and check your calibration
how to use the pre cal readings to give an on going cell check
how to check liniarity on the surface
how to check liniarity underwater
how to check calibration underwater

I think thats it but if I have missed something im sure someone will be along to put me right

the danger of this is its quite a lot to take in and sometimes it goes over peoples heads its a shame its not all laid out in all the training manuals. if it is in your manual can I have a copy?

sorry for the spelling its late!!

Dave

colinicky · 18th November 2006, 21:55

I think as you pointed out Dave it's not in the manual so why waste time teaching it , is "some " instructors attitude ,unfortunately unless you are lucky & know a lot of geographically different people to recommend an instructor or are lucky enough to come across a forum like this you only find out after the event if you did or did not have a good instructor .
Hmmm wonder which I had then ??

denzel · 18th November 2006, 22:33

I think there should be some info about cell life and current limited issues.
But, I also think you should be carefull not to "over teach", so you have to draw the line somewhere.

We should know about cells, and current limited and cell life, but we don't have to be able to build one.

We should know about scrubbers, radial, axial wdell time etc, but we don't need to be able to design a scrubber from scratch incl flow caracteristics, calculations etc.

We should know about leccies and how they work, but we don't need to be able to go to radio shack and build them.

etc.

However, the instructor should know her or his way around it blindfolded.

A complete teaching program is one, but stuffing someone with knowledge not really needed at the time is another.
By the time you're students start to fade out, you definatly have to question yourself.
And if a student really wants to know everything about scrubbers, cells, leccies what have you, then there is always the pub after class

, and books and internet....

Denz.

RonMicjan · 19th November 2006, 03:06

Quote: (Originally Posted by dave t)

this is what I teach on a mod 1 course

theory
cell construction
cell lifetime and why it has one
cell liniarity and how to check
when should I change my cells (pros and cons )
should I change all at once or one at a time (pros and cons )
why its best to use a certain brand of cell (or not) response time ect
how to read the date codes on telydyne cells
what milivolts are and should/shouldnt check them!

practical

how to fit and replace cells
how to check milivolts
how to calibrate and check your calibration
how to use the pre cal readings to give an on going cell check
how to check liniarity on the surface
how to check liniarity underwater
how to check calibration underwater

I think thats it but if I have missed something im sure someone will be along to put me right

the danger of this is its quite a lot to take in and sometimes it goes over peoples heads its a shame its not all laid out in all the training manuals. if it is in your manual can I have a copy?

sorry for the spelling its late!!

Dave

thats good stuff, how do you read the date code on cells?

SINUS · 19th November 2006, 03:18

Quote: (Originally Posted by RonMicjan)

thats good stuff, how do you read the date code on cells?

Right here Ron > http://www.rebreatherworld.com/inspi...ht=sensor+date ...as posted by decoweenie / drmike.

Cheers

Wei Lan

Barfab · 19th November 2006, 08:04

Quote: (Originally Posted by Decodiver)

This is a new thread started on behalf and upon request of Martin:

It may happen if the cells are too old.

***jradomski*** · 19th November 2006, 08:16

martin,
even if the cells are in the right range for 100% oxgen this doesn't guarantee that it will be accurate for anything above this...

I have seen cells that looked fine at a 1.0 po2, but when the controller was showing a 1.3, the real po2 was over a 1.5... These cells were't quite current limited at 1.3, I did manage to get them to just over 1.4 but I needed a po2 of almost 1.8 to do it... (was off loop with 100% o2 in loop and descended down to 9m, at 8m it maxed out)

from general observation, the higher the cells normal output is in air, the earlier it the cell appears to start going non-linear.. And this makes sense since it takes a greater chemical reaction to generate the higher voltages(currents).. This assumes cells of similiar sizes and diffusion rates.. If you go to larger cells where you can increase the electrolyte/lead and increase the diffusion membrane, this behavior would lessen..

mstroeck · 19th November 2006, 08:56

Quote: (Originally Posted by denzel)

But, I also think you should be carefull not to "over teach", so you have to draw the line somewhere.

I do not believe it is possible to "overteach" a rebreather student. If his cells don't work and he is diving a CCR, he will probably die at some point. If he has a problem with that possibilty, and doesn't want to learn how to avoid it, he has bought the wrong gadget. It is a joke that this information is not in any training or uint manuals I have seen so far.

18th November 2006, 20:50	#1 (permalink)
*Decodiver* Administrator Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,197	Cell Linearity This is a new thread started on behalf and upon request of Martin: Quote: (Originally Posted by dive2dive2000) I dive a PRISM and the Unit will not calibrate unless you have 3 working senors and 98.3% or higher O2 One of my pre dive protocols (within 24hrs) is a mv check If an O2 sensor is producing the proper mv out put can it still fail and not read over 1.6???? I personally believe sometimes less gadgets are better, and there are no shortcuts to ccr diving. If you do a mv check and a elevated PPO2 decent to 9m or a pressure pot test Murphy can still KILL you. SHAME on any ccr diver who dosnt own a volt meter(it was required for my PRISM Training). __________________ CCR/OC Trimix Instructor Trainer CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/COPIS-Megalodon/KISS/Sport KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com Rebreather World Terms & Conditions
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18th November 2006, 21:09	#2 (permalink)
colinicky Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Mar 2005 Location: uk Posts: 676	Re: Cell Linearity Well I must admit that I was taught absolutely nothing about checking cells on my Mod 1 Inspiration course & only learnt last week about checking the mv output .I was also told not to take the O2 above 1.6 at all ! Unfortunately not having dived with any ccr divers on a regular basis I didn't pick this up earlier __________________ Colin I trust my rebreather completely , I just don't trust the user onwards & downwards
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18th November 2006, 21:30	#3 (permalink)
dave t Custom Title Allowed! Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss Dolphin Ray Azimuth Home Build Other Rebreather/s: Dolphin Ray Azimuth Home Build Join Date: May 2005 Location: UK Posts: 654	Re: Cell Linearity this is what I teach on a mod 1 course theory cell construction cell lifetime and why it has one cell liniarity and how to check when should I change my cells (pros and cons ) should I change all at once or one at a time (pros and cons ) why its best to use a certain brand of cell (or not) response time ect how to read the date codes on telydyne cells what milivolts are and should/shouldnt check them! practical how to fit and replace cells how to check milivolts how to calibrate and check your calibration how to use the pre cal readings to give an on going cell check how to check liniarity on the surface how to check liniarity underwater how to check calibration underwater I think thats it but if I have missed something im sure someone will be along to put me right the danger of this is its quite a lot to take in and sometimes it goes over peoples heads its a shame its not all laid out in all the training manuals. if it is in your manual can I have a copy? sorry for the spelling its late!! Dave
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18th November 2006, 21:55	#4 (permalink)
colinicky Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Mar 2005 Location: uk Posts: 676	Re: Cell Linearity I think as you pointed out Dave it's not in the manual so why waste time teaching it , is "some " instructors attitude ,unfortunately unless you are lucky & know a lot of geographically different people to recommend an instructor or are lucky enough to come across a forum like this you only find out after the event if you did or did not have a good instructor . Hmmm wonder which I had then ?? __________________ Colin I trust my rebreather completely , I just don't trust the user onwards & downwards
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18th November 2006, 22:33	#5 (permalink)
denzel Holiday diver Current Rebreather/s: Inspiration Classic Other Rebreather/s: Not Bought Yet Join Date: Aug 2005 Location: Perth! Posts: 358	Re: Cell Linearity I think there should be some info about cell life and current limited issues. But, I also think you should be carefull not to "over teach", so you have to draw the line somewhere. We should know about cells, and current limited and cell life, but we don't have to be able to build one. We should know about scrubbers, radial, axial wdell time etc, but we don't need to be able to design a scrubber from scratch incl flow caracteristics, calculations etc. We should know about leccies and how they work, but we don't need to be able to go to radio shack and build them. etc. However, the instructor should know her or his way around it blindfolded. A complete teaching program is one, but stuffing someone with knowledge not really needed at the time is another. By the time you're students start to fade out, you definatly have to question yourself. And if a student really wants to know everything about scrubbers, cells, leccies what have you, then there is always the pub after class , and books and internet.... Denz. __________________ My deepest so far, 558.50 mtr, my rig a LF90D...
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19th November 2006, 03:06	#6 (permalink)
RonMicjan Cap Ron scourge of the NW Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Cape Disapointment, The Graveyard of the Pacific Posts: 1,101	Re: Cell Linearity Quote: (Originally Posted by dave t) this is what I teach on a mod 1 course theory cell construction cell lifetime and why it has one cell liniarity and how to check when should I change my cells (pros and cons ) should I change all at once or one at a time (pros and cons ) why its best to use a certain brand of cell (or not) response time ect how to read the date codes on telydyne cells what milivolts are and should/shouldnt check them! practical how to fit and replace cells how to check milivolts how to calibrate and check your calibration how to use the pre cal readings to give an on going cell check how to check liniarity on the surface how to check liniarity underwater how to check calibration underwater I think thats it but if I have missed something im sure someone will be along to put me right the danger of this is its quite a lot to take in and sometimes it goes over peoples heads its a shame its not all laid out in all the training manuals. if it is in your manual can I have a copy? sorry for the spelling its late!! Dave thats good stuff, how do you read the date code on cells? __________________ Marine rescue, towing and salvage. Interfering with natural selection since 1983. www.tmishop.com Diving bits etc. www.seatowpdx.com The Summer Job
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19th November 2006, 03:18	#7 (permalink)
SINUS Rebreather Aficionado Current Rebreather/s: Other SCR Other Rebreather/s: Other SCR Join Date: Apr 2005 Location: 137km from equator Posts: 199	Re: Cell Linearity Quote: (Originally Posted by RonMicjan) thats good stuff, how do you read the date code on cells? Right here Ron > http://www.rebreatherworld.com/inspi...ht=sensor+date ...as posted by decoweenie / drmike. Cheers Wei Lan __________________ "Silence Is Always Beautiful"
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19th November 2006, 08:04	#8 (permalink)
Barfab New Member Current Rebreather/s: Inspiration Classic Megalodon Ouroboros Ray Azimuth Other SCR Other Rebreather/s: Ray Azimuth Other SCR Join Date: Feb 2005 Location: Italy Posts: 57	Re: Cell Linearity Quote: (Originally Posted by Decodiver) This is a new thread started on behalf and upon request of Martin: It may happen if the cells are too old. __________________ World is a....Rebreather!
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19th November 2006, 08:16	#9 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,998	Re: Cell Linearity martin, even if the cells are in the right range for 100% oxgen this doesn't guarantee that it will be accurate for anything above this... I have seen cells that looked fine at a 1.0 po2, but when the controller was showing a 1.3, the real po2 was over a 1.5... These cells were't quite current limited at 1.3, I did manage to get them to just over 1.4 but I needed a po2 of almost 1.8 to do it... (was off loop with 100% o2 in loop and descended down to 9m, at 8m it maxed out) from general observation, the higher the cells normal output is in air, the earlier it the cell appears to start going non-linear.. And this makes sense since it takes a greater chemical reaction to generate the higher voltages(currents).. This assumes cells of similiar sizes and diffusion rates.. If you go to larger cells where you can increase the electrolyte/lead and increase the diffusion membrane, this behavior would lessen.. __________________ 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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19th November 2006, 08:56	#10 (permalink)
mstroeck New Member Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Nov 2005 Location: Vienna, Austria Posts: 32	Re: Cell Linearity Quote: (Originally Posted by denzel) But, I also think you should be carefull not to "over teach", so you have to draw the line somewhere. I do not believe it is possible to "overteach" a rebreather student. If his cells don't work and he is diving a CCR, he will probably die at some point. If he has a problem with that possibilty, and doesn't want to learn how to avoid it, he has bought the wrong gadget. It is a joke that this information is not in any training or uint manuals I have seen so far. Last edited by mstroeck : 19th November 2006 at 09:04.
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