Do all rebreathers require a bailout bottle on board ?

[Underwater Tourist]

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%?

 

[berndo]

Mate read https://www.revo-rebreathers.com/wp-content/uploads/2016/02/Understanding_oxygen_sensors.pdf it explains everything.

I've seen that paper. It doesn't explain why it's supposedly easier to find which cell/cells are faulty. Flushing with a known gas shows you what cells are off. Doesn't matter if it's 3 cells or 30 cells.

 

[flymolo]

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%?

i don't know of anyone using cells past 12 months.

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

 

[Wibble]

Two of which are old. It's like bringing a 2 year old cell as a spare.
I still don't see how it's easier to identify bad cells.

How do you know if they're the old cells?

They could be fresh ones.

i don't know of anyone using cells past 12 months.

I do. Am quite happy to as well.

 

[Underwater Tourist]

i don't know of anyone using cells past 12 months.

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

Yes I believe its the manufacturer who also specifies that the cells should not be used after 12 (?) months.

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

So I am just curious if the best practice of not diving your cells past 12 months just comes from the manufacturers recommendations or people actually observe an increase in cell failures?

An analogy I am thinking is the "service your regs once per year". I would bet a very small fraction of the divers do that, yet we don't set regs exploding. Maybe "don't dive your cells after 12 months" is the same deal? i.e. a conservative manufacturers recommendation?

Again, I am not a ccr diver, nor am I a pro or anti revo guy, I am just interested to know where this best practice comes from.

 

[flymolo]

Yes I believe its the manufacturer who also specifies that the cells should not be used after 12 (?) months.

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

So I am just curious if the best practice of not diving your cells past 12 months just comes from the manufacturers recommendations or people actually observe an increase in cell failures?

An analogy I am thinking is the "service your regs once per year". I would bet a very small fraction of the divers do that, yet we don't set regs exploding. Maybe "don't dive your cells after 12 months" is the same deal? i.e. a conservative manufacturers recommendation?

Again, I am not a ccr diver, nor am I a pro or anti revo guy, I am just interested to know where this best practice comes from.

I don't know the answer to that. I think 12 months is a fairly standard convention w.r.t. how long a cell should be in service. If I knew my buddy was using expired cells in their rebreather I don't think I'd want to dive with them. I'm not at all inclined to push the limits of my cells.

 

[L13]

i don't know of anyone using cells past 12 months.

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

 

[berndo]

How do you know if they're the old cells?

Because I have a calender and I write the installation date on the cells.

How is it easier to figure out what cells are faulty when you have 5 cells instead of 3? You made this claim.

 

[berndo]

I haven't heard of a Revo diver having a problem because of it.

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

 

[L13]

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

Personally?

I have talked to 4 Revo divers about this. I have also talked to 5 divers of other rigs (Sidewinder, AP, and JJ). Plus, I've been reading the SB rebreather forum for over 2 years(a number of SB rebreather divers dive Revos), as I plot how and which rebreather I am going to start diving when I get to that point (right now, I am leaning towards the Choptima, but who knows what new will be available by then).

All 4 Revo divers have cells over 1 year old in their units. All 4 say that 5 cells make the occasional cell failure a non-issue relatively speaking.

Just because I haven't decided that the Revo is the "best" doesn't mean all of their ideas are "bad". 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.

Being informed on the issues is possible even without personal experience. Knowledge can be acquire in other ways than word of mouth from instructors. 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.