Using back mount doubles as single tanks

[rob.mwpropane]

Well that pulled up what I was looking for thank you!

Somewhat popular in NJ, from what I understand used to be more so.. but I still see them, so not obsolete.

I personally prefer doubles as I feel like no matter what all gas can be diverted to one reg (besides o ring excrusion).

 

[Fishdip]

Independent doubles have neither the pros of manifolded doubles (no regulator switching, access to all gas via the manifold, etc.) nor the pros of sidemount (valves where you can see and easily manipulate them). I also have not personally seen or heard of any widespread manifold failures to make me think they are inherently more failure-prone than diving without a manifold. The pros/cons just don't line up for me - either dive manifolded doubles or dive sidemount if you want independent tanks.

I dive sidemount. So switching all the time is no issue! My issue in testing is reaching the isolator. I can reach the tank valves really easy even more so with them having side mount extended valves. Also for moving them around I find pulling the bands to be fast and simple.

 

[PEDiver]

There's actually been a push by some to completely do away with the isolator valve because in a lot of OOG situations the diver has been found with one tank still with gas. They either rolled it the wrong way or forgot or whatever.

That's always in the back of my mind when I splash. Always check my isolator

I feel like that must originate out of complacency or bad training practices. I always check my isolator before every dive, and I never store them with the isolator closed. If you're constantly opening/closing the isolator, then I can see someone either filling it closed or leaving it closed and splashing which would lead to an OOG (seemingly at least) situation. But that should never be the case since it should be part of your pre-dive checklist.

 

[Fishdip]

Why? In what configuration would you use them? What do you gain?

Simple to build using any tanks on hand. Reaching the left and right valves are simple but I struggle with middle. And its so much more simple to move and transport with out the manifold.

 

[PEDiver]

I dive sidemount. So switching all the time is no issue! My issue in testing is reaching the isolator. I can reach the tank valves really easy even more so with them having side mount extended valves. Also for moving them around I find pulling the bands to be fast and simple.

Do you have a specific use case for diving doubles vs. sidemount? Just curious what kind of diving you want to do with independent doubles.

 

[rob.mwpropane]

I feel like that must originate out of complacency or bad training practices. I always check my isolator before every dive, and I never store them with the isolator closed. If you're constantly opening/closing the isolator, then I can see someone either filling it closed or leaving it closed and splashing which would lead to an OOG (seemingly at least) situation. But that should never be the case since it should be part of your pre-dive checklist.

I personally agree, although I think statistically it's safer to do away with the isolator. More people would be alive today if there was no isolator at all. (as per memory of a discussion hashed out on here by people with much more experience then I). An o ring extrusion is way more rare than a roll off or mishandled valves.

I can only assume that in a panic, complacency or rolled valve or maybe unable to manipulate the valve the right way due to panic?.... the end result has been bad.

Again, personally, I am a pipe layer / gas fitter by trade. I have "righty tighty lefty loosey" etched into my DNA, so it's hard for me to fathom not turning the right way, but if I put myself in the shoes of an accountant or a banker then maybe I can see. Regardless how "great" I think I am I make sure to manipulate the isolator and do valve drills on every dive... I don't want to be "that guy".

 

[Lorenzoid]

Again, personally, I am a pipe layer / gas fitter by trade. I have "righty tighty lefty loosey" etched into my DNA, so it's hard for me to fathom not turning the right way, but if I put myself in the shoes of an accountant or a banker then maybe I can see.

My wife and I are full cave divers, and every now and then I see her start to turn a valve the wrong way and then realize her mistake. For some people, it will never become etched into their DNA. It concerns me a bit.

 

[Fishdip]

Do you have a specific use case for diving doubles vs. sidemount? Just curious what kind of diving you want to do with independent doubles.

Big one is boat use as it stands I hate sidemount on a boat. And really I dont see any real gain other then one reg use. Plus me not being the best at reaching the isolate valve and being able to separate for transport is also a plus.

 

[rob.mwpropane]

My wife and I are full cave divers, and every now and then I see her start to turn a valve the wrong way and then realize her mistake. For some people, it will never become etched into their DNA. It concerns me a bit.

I agree 100%. My wife (if she actually would dive, lol) would never get the muscle memory down for turning a valve, especially if she panicked.

And who knows, I don't think I'm impervious. I feel like that now, but old age, complacency.. who knows. I'm aware that it's a possibility, so I practice.

We had a guy last year wreck his personal plane that he had countless hours in because he forgot to do something on takeoff. 30 years in that plane and one day he just forgot. He wasn't injured, but it's eye opening and all the more reason for checklists and practice.

 

[OTF]

My twin tank (and that of my wife) are manifolded, but they do not have an isolator exactly for this reason. I always want to be sure that both regs have access to all of my gas.
However, these Aralu twin tanks have a spring-loaded reserve, which ensures that, even after a catastrophic failure (like an O-ring extrusion), and after closing the affected valve, you can pull the reserve and retrieve a substantial amount of air.

That's the most visually beautiful set of doubles I've ever seen. Love the colors and decals. But man that's weird compared to what I dive.

Does this not use bands? Is it just held together with the manifold and oversized boot? How does it attach to the harness/plate? What are the clamp-on cones around the tank necks, weights? Does that center post rotate?