JJ-CCR tank valve position

[LanceRiley]

Hi why is it sometimes the tank valve is on top and sometimes it's on the bottom. any advantage to it?
I also noticed sometimes it uses a tek3 first stage? any specific reason?

 

[Wibble]

GUE configuration?

The "standard" config is with the valves on the bottom as they're easier to get to and not so exposed. This normally uses 3 litre cylinders, one oxygen, the other diluent. Bailout is then clipped to the side as a normal decompression stage cylinder.

The GUE configuration has a couple of 7 litre cylinders used for both diluent and bailout. These have the valves on the top as that is where Open Circuit divers would expect to find them and apparently it's really hard to learn new tricks. The two 7's are also soft manifolded; an HP hose between the cylinders; the valves have two knobs on the top; one for the regulator and the other for the soft manifold. They also have a longhose and shorthose for out-of-gas drills/use.

 

[grantctobin]

^that, mostly. On a Fathom, it is common to run the standard 3L/S30/S40/5-7L valves up. Traditional dil bottle location becomes an inflation bottle, right bottle an oxygen bottle, with diluent all offboard.

The Thought Process Behind GUE’s CCR Configuration

Global Underwater Explorers is known for taking its own holistic approach to gear configuration. Here GUE board member and Instructor Trainer Richard Lundgren explains the reasoning behind its unique closed-circuit rebreather configuration. It’s all about the gas!

gue.com

Grokking The FATHOM CCR: My Dive into the Nuts & Bolts with the Inventor

Launched in 2016, the FATHOM mechanical closed circuit rebreather (mCCR) has gained supporters among deep cave explorers and those distrustful of underwater electronics, who say they favor its simplicity, robustness and unique valve system that overcomes the disadvantages of traditional mCCRs...

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[sea_ledford]

I did a Prism2 course with the DSO from California Academy of Science last year. They do a LOT of remote and deep work, and have modified the units to suit the purpose. We ran AL30's valves up, standard dil/O2 on each side.

I was hesitant at first as I like the ease of reaching the valves down vs where they are in doubles, but on the Prism at least, the valves end up being just a little higher and further apart than doubles so they were easy to reach. Additional bonuses I wasn't even thinking about: flat bottom, longer tanks lets the unit stand up on its own, no stand needed. Having the weight of the valves and regs up top made the unit trim out like a dream.

I'm contemplating trying out valves up on my SF2, but it might completely jack with the trim based on where the counter lung is.

 

[Wibble]

Having the valves up would mean that they'll bang into a wreck if wriggling. Would rather have the bottom of the cylinders up than valves.

 

[MattK911]

Having the valves up would mean that they'll bang into a wreck if wriggling. Would rather have the bottom of the cylinders up than valves.

The valves will bang into the wreck no more than a set of doubles.

This is a Fathom with 3L’s and a Halcyon Evolve 40 wing. I don’t wreck Dive, but I do squeeze through some smaller caves. I’m personally more worried about the breathing loop hoses than the regs and valves .

 

[GF99/99]

Or you could be like me and throw a wrench in the system and mount 2 up and 2 down.

I'm sure someone is going to give me crap for this setup but for open ocean exploration deep diving it works. Is it the correct setup for others doing different styles of diving maybe not but for the very specific type of diving I am doing it works great.

But I do agree with @Wibble for overhead environments all valves down protected in the stand is best.

 

[Wibble]

Or you could be like me and throw a wrench in the system and mount 2 up and 2 down.

I'm sure someone is going to give me crap for this setup but for open ocean exploration deep diving it works. Is it the correct setup for others doing different styles of diving maybe not but for the very specific type of diving I am doing it works great.

But I do agree with @Wibble for overhead environments all valves down protected in the stand is best.
View attachment 756563

(OT: How do you find that Gralmarine torch? Is it the narrow + wide one? Good beam pattern? Adjustable for crap visibility?)

 

[boriss]

Hi why is it sometimes the tank valve is on top and sometimes it's on the bottom. any advantage to it?
I also noticed sometimes it uses a tek3 first stage? any specific reason?

Sometimes there are just physical/packaging reasons for it as well. Here's one example with a Fathom where the flat-bottom aluminum cylinders allow the entire system to stand on its own without a stand: Just ordered my FATHOM!

Here's another case on the rEvo where you can install any tank you want and they fit. Imagine the valves were at the top, then there are limitations to which cylinders can be used (especially without a stand)

Here are a few examples with JJ, where tanks are mounted both ways, depending on what the owner prefers, but note how high the unit stands on its stand to allow for these configurations

Here are more configurations with different stand heights, tank sizes/orientations, etc.

As far as 1st stages:
Most good rebreathers use the Apeks DS4 1st stages. It's a fraction of the price of a Tek3, it's lighter, smaller, has simpler hose routing for CCRs, etc. Both are environmentally sealed, over-balanced diaphragm designs. I don't know that the Tek3 has anything of benefit to a CCR diver; they're made for twinsets.

 

[Wibble]

DS4 vs Tec3

Basically it's just the hose routing. They are very similar internally, sharing the same service kit.

The DS4 has 4 low pressure outlets angled circa 90 degrees apart (slightly different, but close enough). For a bailout stage, the hoses are a bit "sticky upward".

The Tec3 has 3 low pressure ports all angled downwards. They're available in "left" and "right" hand configurations. This makes it far better for a twinset rig.

When moving to CCR from OC, many people have Tec3's in their regulator collection and discover that they make exceptionally good bailout / stage regulators because of the hose routing. Three downward facing outlets is perfect for the bailout regulator on a 1m/3'3" hose; a normal BCD hose for offboard gas/drysuit/buoyancy/wing/SMB plumbing; and a QC6 bailout connector. Can't use a DS4 as one of the hoses will point upwards.