CCR Selection priorities

[boriss]

"Supposedly" -- I openly admit what I heard is not substantiated by concrete evidence in my hand. The person that told me this used to be a distributor for a CCR that is CE rated.

And as Brad said, you can alert failures. My JJ has a notification on page 11 of the owners manual (https://jj-ccr.com/wp-content/uploads/2020/06/Version_210_ENG.pdf) saying it does not pass CE specification when oriented head down (and my dive yesterday had been crawling through rocks head down on a JJ, that was, err, fun).

@kensuf based on your experience, although unscientific, where would you think the Fathom would "fail" had it gone through CE certification? Like in what position is it "fun" as the JJ was? Thanks!

Also, as an aside, if CE certification is so expensive, then why aren't units without CE certification cheaper?

 

[rsingler]

and my dive yesterday had been crawling through rocks head down on a JJ, that was, err, fun).

Same challenge for me going vertical, head down for two decks in a trunk in the Spiegel Grove. CL's collapsed around the inflow tee and it was like sucking thru a straw. No room to turn around.
Haven't had another opportunity to test it, but my plan next time is to dump wing and inflate CL's to higher volume, and see if that keeps the passage open.
Thoughts, @kensuf ?

 

[kensuf]

@kensuf based on your experience, although unscientific, where would you think the Fathom would "fail" had it gone through CE certification? Like in what position is it "fun" as the JJ was? Thanks!

Also, as an aside, if CE certification is so expensive, then why aren't units without CE certification cheaper?

I don't know enough about how the CE tests operate to weigh in on either of these questions. I suspect the Fathom would probably get a similar result in the head down vertical orientation like the JJ did.

Same challenge for me going vertical, head down for two decks in a trunk in the Spiegel Grove. CL's collapsed around the inflow tee and it was like sucking thru a straw. No room to turn around.
Haven't had another opportunity to test it, but my plan next time is to dump wing and inflate CL's to higher volume, and see if that keeps the passage open.
Thoughts, @kensuf ?

Yeah, I had a "sticky inhale" dropping through a coral tunnel from 180' to 270' last week. Dumping the wing has no impact, the problem is the gas gets trapped in the bottom of the CL. Just go slightly closer to horizontal when you need to inhale, or use the DIL mav to go open-loop.

 

[Dsix36]

Same challenge for me going vertical, head down for two decks in a trunk in the Spiegel Grove. CL's collapsed around the inflow tee and it was like sucking thru a straw. No room to turn around.
Haven't had another opportunity to test it, but my plan next time is to dump wing and inflate CL's to higher volume, and see if that keeps the passage open.
Thoughts, @kensuf ?

Any RB should have an anti-collapase device built inti the inhale counter lung that will prevent this from being a real issue.

 

[rsingler]

I wasn't very clear. I was hoping to dump the wing to allow me to add enough extra volume in the CL's to make up for the fact that most was ending "up" in the bottom of the lung. I was hoping that enough CL volume would open a passage at the shoulder, while dumping the wing would allow me to stay neutral.
Maybe it won't help.

 

[rsingler]

Any RB should have an anti-collapase device built inti the inhale counter lung that will prevent this from being a real issue.

Alas, the sole fault I have identified in the JJ.
The problem isn't at the tee, but rather the part of the lung that wraps around the top of the shoulder that goes flat when the CL volume floats up to the base when head down.

 

[Dsix36]

Alas, the sole fault I have identified in the JJ.
The problem isn't at the tee, but rather the part of the lung that wraps around the top of the shoulder that goes flat when the CL volume floats up to the base when head down.

a length of plastic spiral tubing attached to the T-piece should sort this problem

 

[admikar]

If anyone knows a solid way to teach valve directions to new doubles divers, I'm all ears.

For isolator on put your hand on it and look all the way left. Valve rotates the same way as your head.
For right/left post, give anything that twists (jar, bottle etc). Tell them to hold it horizontal and open it. Valves follow same direction.

 

[inquis]

Rig on a bench with valve handle pointed at you. Turn clockwise for off. Practice with each hand, 100x. NOTHING CHANGES when it's on your back pointed to the right, left, or up. Don't over think it.

 

[rsingler]

A similar unit that comes in at a lower price tag would be the JJ, which of course has it's differences which I find to be cons (o2 injection on the inhale side of the scrubber, heavy and bulky stand, no BOV, axial scrubber (though a radial is available as an option) and a few other things). It's still very similar in function and considerably cheaper.

With your recent posts on the Fathom, I thought I would bump this thread as a JJ diver.
To give you some things to say, "Yes, but..." here are some thoughts ...

Looking at your reply above,
1) why is O2 Injection on the inhale side a bad thing? As I ponder the horrific stuff, there's ascent with a hypoxic mix, and loss of consciousness within a couple of breaths, which could potentially be alleviated by a rapid increase in pO2, better injected on the inhale side. But forethought would also alleviate the problem. Conversely, there's inadvertent O2 spiking, which is far more common, yet less immediately fatal, and lessened by injection on the exhale side;
2) the stand isn't really very heavy, yet is a bit bulky when trying to pack into a Pelican case. A bit of disassembly is required. As a result, I ponder the Choptima for a bucket list trip to Chuuk. But I like the JJ for my arthritic shoulders, because the valves are down;
3) no standard BOV, but I'm contemplating one. Easy enough to add; just not standard;
4) yes, radial scrubber available.
So, I conclude it's just heavier. Maybe a lot. But the Choptima is portable and the front-mounted CL with positive static lung load, vs mCCR as a better design, is a bit of a question for deep dives.

Why would you choose Fathom over both JJ and Choptima? (Except for the JJ head down issue, which I'm working to eliminate with a shoulder coil stent for the inhale CL) Does it really just come down to mCCR vs eCCR?