Do all rebreathers require a bailout bottle on board ?

[broncobowsher]

...

Judging by what people who dive revo say, they have cells working perfectly fine after 18-24 months.

...

12 months, fine
15 months, readings don't really match the others as much
18 month, it is in the O2 anaylzer.
24 months, the analyzer is needing a lot of cals every time it is used, air mV readings are low, time to swap out with a year old cell and have it work predictable again.

Cells don't 'just die'. They age. Even old they will still work, to a degree. If all you care about is a reading and it will read over 1.6 PPO2, yes the year+ old cells will generally still do that. If you like the PPO2 reading to overlay really close, not have a cell that is 0.1, 0.15 off from the others, keep fresh cells.

 

[berndo]

This is the power of the amazing invention of writing by civilizations before us. It allows the transfer of knowledge across the planet and across the centuries. It allows us to aggregate knowledge across instructors, etc.

Yeah, unfortunately these days, some people read stuff on the internet and compare non-fiction books with random anecdotal stories they read on the internet or seen in a youtube video.

 

[Wibble]

Today's cells April 2023 in age order: 2/23, 8/22, 3/22, 8/21, 6/21

Had a suspect cell in 2021 which was swapped out early.

I did notice that cell 2 was reading a little higher than the others on Sunday's dive.

All of them were not current limited when I did the O2 flush at 9m/30ft before ascending to 6m/20ft.

 

[L13]

Yeah, unfortunately these days, some people read stuff on the internet and compare non-fiction books with random anecdotal stories they read on the internet or seen in a youtube video.

Are you suggesting that I should completely discount your posts on SB as containing no usable information?

I prefer to take them as containing useful information when properly integrated and discounted with the whole body of information available to me, both on and off the internet. I do discount it more than I would other wise given the complete lack biographical information in your SB profile.

 

[berndo]

It's a lot easier if you've more than three to work out which one's out of kilter.

Still wondering if you can explain why it's a lot easier to find faulty cells when you have two old extra cells in your unit?

 

[rjack321]

Just curious. How many revo divers do you know and talked to about this?

They all can't shut up about their 5 cells, that's the reason every CCR thread on SB comes back to revos and their magical 5 cells, 3 of which are often older than a year

 

[rjack321]

For a non ccr diver, is there a stat on cell failure? Maybe something like: after 1 year the probability of a failure is x%, after 1.5 years it’s y%?

There is nobody even collecting this information nevermind publishing it. 12 months of use is the SOP for every manufacturer except Revo, which has their magical old cell replacement rotation - which is based on the hypothetical "data" on failures in Paul's paper.

 

[BlueTrin]

There is nobody even collecting this information nevermind publishing it. 12 months of use is the SOP for every manufacturer except Revo, which has their magical old cell replacement rotation - which is based on the hypothetical "data" on failures in Paul's paper.

I guess nobody prevents them to change them on a yearly basis at the cost of paying two more cells every year?

 

[Wibble]

Still wondering if you can explain why it's a lot easier to find faulty cells when you have two old extra cells in your unit?

Because there’s four other cells to compare it with if one is outside specification. Or three comparators if two play up.

Why do you assume old cells are broken?

Why do you replace all three cells every year?

 

[Tassi Devil Diver]

For a non ccr diver, is there a stat on cell failure?

Here are my stats on cell failure based on a sample size of 30: out of packet 0% failed, 0.5 years 0% failed, 1 year 0% failed, 1.5 years 0% failed, 2 years 0% failed, 2.5 years 10% failed, 3 years 25% failed (based on as cell checker), 3.5 years 50% failed (based on cell checker), 4 years 100% failed (based on cell checker). These are for rEvo B cells.

the cells i use have a "do not use after" date written on the label, and when i install them i write the date they went into service, and then i make sure to change them out either one year from the date i installed them or before the "do not use after date", whichever comes first. i usually end up switching out my oldest cell with my spare cell and then buying a new spare

The cells I use the (rEvo B) has an "install sensor prior to date" followed by the text "follow manufacturer recommendation for censor replacement".

I do think their 5 sensor solution will become obsolete once solid state sensors become ubiquitous, but we have a ways to go before that happens.

Once solid state sensors become ubiquitous, I would use two one on the controller and second on the redundant PO2 monitor.

Most (maybe all?) Revo divers do. I haven't heard of a Revo diver having a problem because of it.

6 rEvo divers in my region have had very few problems with rEvo 6 month cell replacement procedure using rEvo B cells. However those that have tried the AI cells have experinced some early failures. Personally I would not use an AI cell in my unit knowing how reliable the rEvo B cells are.