SF2 or REvo rebreathers

[cathal]

The nut came loose and fell off inside the counterlungs. My Revo class was taught by Paul himself. This possibility certainly wasn't covered in class, nor is it part of the build checklist.

As to your leaky valve question, I don't know any leaky valve without the limitation, which is why I'll never own a leaky valve ccr.

Usually 10/65 or 10/70 at 300'ish feet. It's not the helium, it's that back mounted counterlungs suck. Anyone who has spent serious time on bmcl and then switches to fmcl never tries to this point. Again, dive out of trim, and it's not an issue.

Thanks for the response, I still don't understand the WOB issue, in trim or pretty much 25 degrees either way it breathes fine to me, its when you are vertical on the surface waiting to be picked up or on the diver lift when the WOB is crap.

Regarding the OPV I had mechanical damage to my OPV after a flight and when I tried to do a + or - test the unit wouldn't pass and that's how I discovered the issue. A nut coming loose is certainly a strange one, cant say I've heard of it happening before or since and especially with it passing the pos/neg tests while being loose.

 

[victorzamora]

Can you point to any other rebreather on the market with a leaky valve that does not have a depth limitation?

The Pelagian is a CCR with a leaky valve without depth limitation. I don't think they're made anymore, but I think they were the originals with that design. Currently, the Fathom CCR (I believe) has the same.

I have no dog in this fight, btw...I have no time on the SF2 and practically zero time on the rEvo.

 

[cathal]

The Pelagian is a CCR with a leaky valve without depth limitation. I don't think they're made anymore, but I think they were the originals with that design. Currently, the Fathom CCR (I believe) has the same.

I have no dog in this fight, btw...I have no time on the SF2 and practically zero time on the rEvo.

Thanks for that, can anyone explain how a leaky valve can not be depth limited as my understanding was that the ever-increasing I.P of the O2 would cause the O2 to eventually spike hence the use of absolute pressure 1st stages on them.

 

[victorzamora]

Thanks for that, can anyone explain how a leaky valve can not be depth limited as my understanding was that the ever-increasing I.P of the O2 would cause the O2 to eventually spike hence the use of absolute pressure 1st stages on them.

The Pelagian, Fathom, etc use a needle valve. It's essentially a manually-adjustable orifice used with an uncapped first stage.

Now, the pros and cons are open for debate...but that's the function. Here's a link to one, here's a link to info regarding another one. There's a few others, but those are the ones I could find easily. Supposedly the flowrate is less sensitive to needle position than you'd think, but I've never dove one and can't say much either way.

 

[Superlyte27]

Unit passed positive and negative. I'm guessing it had been loosening for weeks. Then at the worst moment came the flood.

For minor dives, not real deep or real far in, no big deal, but 10,000' in or 6 hours of deco, I really don't want to bail out.

 

[cathal]

but 10,000' in or 6 hours of deco, I really don't want to bail out.

Agreed, I can only imagine how committed you are to your unit at that stage, funnily enough 3 of my dive buddies went form front mounted lungs to the rEvo and the first guy in particular swears he will never go back to front mounted lungs. He used it on this 500ft dive here
Since that dive he swears by the rEvo.

 

[cathal]

The Pelagian, Fathom, etc use a needle valve. It's essentially a manually-adjustable orifice used with an uncapped first stage.

Now, the pros and cons are open for debate...but that's the function. Here's a link to one, here's a link to info regarding another one. There's a few others, but those are the ones I could find easily. Supposedly the flowrate is less sensitive to needle position than you'd think, but I've never dove one and can't say much either way.

Thanks for that, don't want to side track this thread by comparing the difference between a needle valve and CMF.

 

[Superlyte27]

Agreed, I can only imagine how committed you are to your unit at that stage, funnily enough 3 of my dive buddies went form front mounted lungs to the rEvo and the first guy in particular swears he will never go back to front mounted lungs. He used it on this 500ft dive here
Since that dive he swears by the rEvo.

Which front mounted rebreather?

 

[cathal]

Which front mounted rebreather?

AP Inspiration

 

[Superlyte27]

AP Inspiration

Yeah, that doesn't count