Question Isobaric counter diffusion in CC

[Alekseolsen]

This post is focused on the use of multiple diluents for the purpose of validating cells is it not? It seems you are claiming to be carrying multiple diluents for the purpose of validating cells during your dive, If that is the case it seems like a lot of effort , expense for a very limited result. Then you imply that only you and a select few of diving elite are doing the type of diving that warrants such extravagance .
I would accept the argument that multiple diluents can be used to mitigate the effects of IBCD in certain dive profiles but to carry multiple dil cylinders for the purpose of validaitng cells at depth seems highly impractical in real life.

Guess I'm in way to deep waters here - but plugging in the bailut mix(es) would deconstruct the entire argument. Checking @tbone1004's profile it's evident he dives a Kiss, which does indeed use a dilout config.
It's sort of scares me that a CCR instructor seems to make up issues about other ways of doing a dive. I mean criticism is a healthy thing, but would have to be actual criticism and not strawmen

 

[tbone1004]

This post is focused on the use of multiple diluents for the purpose of validating cells is it not? It seems you are claiming to be carrying multiple diluents for the purpose of validating cells during your dive, If that is the case it seems like a lot of effort , expense for a very limited result. Then you imply that only you and a select few of diving elite are doing the type of diving that warrants such extravagance .
I would accept the argument that multiple diluents can be used to mitigate the effects of IBCD in certain dive profiles but to carry multiple dil cylinders for the purpose of validaitng cells at depth seems highly impractical in real life.

You are putting a lot of words in my mouth. If you don't believe in carrying multiple bailout gases that's on you, but don't try to put words in my mouth that are directly contrary to my initial recommendations in this post

 

[GF99/99]

This post is focused on the use of multiple diluents for the purpose of validating cells is it not? It seems you are claiming to be carrying multiple diluents for the purpose of validating cells during your dive, If that is the case it seems like a lot of effort , expense for a very limited result. Then you imply that only you and a select few of diving elite are doing the type of diving that warrants such extravagance .
I would accept the argument that multiple diluents can be used to mitigate the effects of IBCD in certain dive profiles but to carry multiple dil cylinders for the purpose of validaitng cells at depth seems highly impractical in real life.

No this post was to focus on ICD and dil switching, nothing to do with cell validation, check the OP's original question. @tbone1004 only brought up cell validation because it was bonus by-product of dil switching.

As far as carrying multiple "diluent" well yes a "bailout gas" is a diluent. And if you read the OP's question he was referring to 100m dives. Yeah sure in theory you could just carry a pile of only 1 gas but the majority of people doing 100m dives will carry multiple different B/O gases mixes, as @tbone1004 already mentioned several post back usually a deep trimix, some kind of intermediate trimix, some kind of deeper deco gas, and the some kind of shallower deco gas. No where in this entire post does he mention that multiple dils were carried to validate cells. Reason for carrying multiple B/O (that can be plugged in and used a dils) is because that is SAFE diving. Sorry but you can tell me im wrong all day long but the reality is I am not, its very plain and simple that its SAFE to carry B/O to get to surface. The SAFEST way to conduct a 100m dive is to carry sufficient B/O gas to get you or your buddy to the surface safely and efficiently (key word there) and to do this is to carry multiple gas mixes both trimix and deco gases (sorry but just carrying lost of 1 mix is not practical or safe, I don't know any instructor that would teach this) Now yes a by product of having these gases on you is you can dil switch off of them and validate cells (key words here by product). But that is not the main purpose of them. The primary purpose is to save your a$$ should your rebreather fail so you can surface safely on O/C

Guess I'm in way to deep waters here - but plugging in the bailut mix(es) would deconstruct the entire argument. Checking @tbone1004's profile it's evident he dives a Kiss, which does indeed use a dilout config.
It's sort of scares me that a CCR instructor seems to make up issues about other ways of doing a dive. I mean criticism is a healthy thing, but would have to be actual criticism and not strawmen

What is wrong with plugging in a B/O gas?? And what does diving a Kiss have anything to do with it?? I plug in B/O gas all the time and I'm a non Kiss diver. I even plug B/O into a full ECCR that has an onboard 3l dil tank.

 

[GF99/99]

^ these are my picks-

Personally I like to keep it as simple as possible if you have a complicated switching scenario (or trying to make it so ) and you have some problem on top of that then you will have a, lot of stress- I think stress is where you start making mistakes and if you have 3-4 hours of deco in front of you then you cant run home when it starts falling apart

If your doing a 100m + dive your committed to one dive for the day - and i'Il prefer to do a longer bottom time and just accept the deco - fretting about saving 20 min is fruitless in my view

I dont tworry about a flush unless theres an obvious reading problem as @wedivebc mentioned -youve already planned what po2 you are expecting at the bottom and at 21m no? so maybe at 6m you could flush but i run it manually at 6m anyway similar to what @tbone1004 said mostly so I can control the loop volume

on the ascent you burping the loop so surely thats enough of a flush - not sure what changes in the helium volumes are - maybe someone has done the math on this

You are missing the point I am making. Please re-read what I am talking about for one of the main reason to dil switch. It has to do with not getting and ICD hit if you have to B/O in the shallows. Dil switching can actually make your dive planning less complex on deep dives. Question - Isobaric counter diffusion in CC post #47

"Also another thing to note about dil switching that not alot of people think about and this is actually one of the main reason I was taught to dil switch is for Bailing Out, yes shaving deco time off is a great byproduct. The main topic of this post was ICD and it actually falls right in line with why I was taught to dil switch on ascent. If your doing a 180m dive on a 5/80 (or something) and you do not dil switch on ascent let say you have an issue at 21m with your unit and you need to bail out what gas do you bail out to?? Do you know your 50% is safe to go to with out getting an ICD hit?? (chance are probably not) if not then what trimix do you go to and then how long do you have to stay on that until you can switch to your 50%. Or what if you at 45m and you need to bailout what gas can you safely switch to directly from your unit with out getting at ICD hit? And How long do you have to stay on that gas to then switch to you next one? The bail out to O/C what if scenarios to check for ICD hits become very dive planning intense. I am not saying it can not be done but it make the B/O planning fairly complex. And I would venture to guess that most people do not even check these kind of things and if they are very minimally. There are ALOT of different what if scenarios to run through for B/O on ascent and checking for ICD."

You want to to talk about complicating a dive well them list all the "what if" B/O to O/C gas sceneries that will not give you and ICD hit and all the safe depth you can switch to a how long you need to say on each gas befor you can switch??

When you are planning a sub 100m do you actually check all your different B/O scenarios? and I am not talking about B/O after your bottom phase. I am talking about B/O in the shallower portions.

Also try doing a 200m dive with no dil switching, its not just 20min of deco. Now your racking up crazy amounts of CNS and depending on your unit you are starting to push your scrubber. Do you really want to stay in the water that much longer???

 

[Alekseolsen]

What is wrong with plugging in a B/O gas?? And what does diving a Kiss have anything to do with it?? I plug in B/O gas all the time and I'm a non Kiss diver. I even plug B/O into a full ECCR that has an onboard 3l dil tank.

Nothing wrong with plugging bailout - I just wanted to point out that @wedivebc constructed a strawman, alternativly is worryingly ignorant for a ccr instructor when stating "who would bring several diluents"
The Kiss was relevant as it doesn't have a onboard dil. (And yes, I've been thought to plug offloaded DIL on my MEG as well)

 

[GF99/99]

Nothing wrong with plugging bailout - I just wanted to point out that @wedivebc constructed a strawman, alternativly is worryingly ignorant for a ccr instructor when stating "who would bring several diluents"
The Kiss was relevant as it doesn't have a onboard dil. (And yes, I've been thought to plug offloaded DIL on my MEG as well)

Maybe I am wrong but I think that @tbone1004 is getting at is that for a 100m + dive you are already carrying multiple B/O gas with different mixes that acts as a dil/dilouts regardless of what unit your diving. I think the reason for his comment was because someone turned his words around and made it sound like he purposely would bring multiple 3l diluents on a dive just for fun to verify his cells. This is not the case as I just mentioned it is really a byproduct of carrying your already needed B/O gas.

 

[Alekseolsen]

Maybe I am wrong but I think that @tbone1004 is getting at is that for a 100m + dive you are already carrying multiple B/O gas with different mixes that acts as a dil/dilouts regardless of what unit your diving. I think the reason for his comment was because someone turned his words around and made it sound like he purposely would bring multiple 3l diluents on a dive just for fun to verify his cells. This is not the case as I just mentioned it is really a byproduct of carrying your already needed B/O gas.

This is my exact understanding as well, and the "bring several 3 liter bottles" is what I tried to point out as a strawman - but I must have done so very poorly!

 

[GF99/99]

This is my exact understanding as well, and the "bring several 3 liter bottles" is what I tried to point out as a strawman - but I must have done so very poorly!

No worries, I think it all got a little confusing.

I understand the point about bringing multiple 3l dils just for the sake of dil switching being pointless. I think we all agree this has no value and overcomplicates a dive.

But I think it was just assumed that for a 100m dive the diver already has to carry multiple B/O gas mixes and alot of times that would be a 50% and 100% (or some kind of deeper deco and shallow deco gas) so @tbone1004 was just making the point that these can be used to validate cells at high SP's to confirm your cells are not current limited. But these are B/O gas you are already carrying on you not something extra.

I think also of the confusion is naming convention; Diluent, dilout, bailout, offboard, etc. The reality is anything that is breathable is a diluent does not matter what tank it comes from. Some may argue that this is wrong but that is just how I see it.

 

[tbone1004]

No worries, I think it all got a little confusing.

I understand the point about bringing multiple 3l dils just for the sake of dil switching being pointless. I think we all agree this has no value and overcomplicates a dive.

But I think it was just assumed that for a 100m dive the diver already has to carry multiple B/O gas mixes and alot of times that would be a 50% and 100% (or some kind of deeper deco and shallow deco gas) so @tbone1004 was just making the point that these can be used to validate cells at high SP's to confirm your cells are not current limited. But these are B/O gas you are already carrying on you not something extra.

I think also of the confusion is naming convention; Diluent, dilout, bailout, offboard, etc. The reality is anything that is breathable is a diluent does not matter what tank it comes from. Some may argue that this is wrong but that is just how I see it.

Correct, though even on my Meg *which does have a 3L bottle*, I don't use that 3L bottle for dil, instead using it for inflation, and have it in a rack for boat diving with twin LP50's that I use for dilout. I wouldn't use an onboard 3L bottle for diluent on that deep of a dive, that bottle is far better off being used for inflation.

 

[GF99/99]

Correct, though even on my Meg *which does have a 3L bottle*, I don't use that 3L bottle for dil, instead using it for inflation, and have it in a rack for boat diving with twin LP50's that I use for dilout. I wouldn't use an onboard 3L bottle for diluent on that deep of a dive, that bottle is far better off being used for inflation.

Yup depending the setup and dive I often use my 3l onboard for wing/suit inflation only as well. Glad im not the only one doing this.