Second stage connection

[grantctobin]

Too bad. I've been doing regulator switches for decades, probably learned long before you started diving. Thanks for the info and advise.

As luck would have I am the owner of freshly serviced SP AIR 1 serviced by our own @rsingler so I'll be using that my new ID configuration.

Yawn. Survivorship bias - Wikipedia Best of luck and hope your IPs stay identical.

 

[Angelo Farina]

I have a rare left-handed Scubapro 109 (which technically is called a 129), of course converted to BA:

Bought here on SB, you can ready the full story here:
Scubapro mod. 129

 

[broncobowsher]

I recall some of my Hollis regs can be built either side.

 

[Angelo Farina]

These can be connected at the same time like the AIR1? The answer to why concerns independent doubles and the elimination of regulator switches.

Yes for the the D420, you can use it with two hoses attached on both sides, as it was common to do with the Pilot. However, at the time this was done for providing more air flow to the Pilot (a single MK5 of the time was not capable of providing the incredible air flow of which the Pilot was capable, although soon the problem was solved adding the central-top superflow port on the first stage and the conical seat).
I do not think that it is a clever idea to have to close alternatively the valves of the two tanks for alternating the air usage from the two tanks...
But perhaps here I did not understand entirely your usage scenario with independent doubles. Perhaps you keep both valves open, and you close one of them only if required...

 

[rsingler]

I have a rare left-handed Scubapro 109 (which technically is called a 129)

Found my first 129 just this month! Not as pretty as yours, but I'm cleaning it up and servicing it. So excited to have found one! I may stick it on my bailout just for the bling!

 

[GJC]

These can be connected at the same time like the AIR1? The answer to why concerns independent doubles and the elimination of regulator switches.

This is an interesting idea.

So you would connect both LP hoses to 1 second stage. 1 tank would drain to empty before the other started to drain or would they drain equaly or would you turn tank valves on and off to switch tanks?

Would a Y connector that connected 2 tank LP hoses to 1 LP hose work for you?

 

[scrane]

Any of the Poseidons? With a dedicated first stage for odd IP.

 

[gqllc007]

D420

 

[gqllc007]

Any of the Poseidons? With a dedicated first stage for odd IP.

This is true even the Triton could be swiveled both sides..I have two of them still

 

[AfterDark]

So my concept is as follows:

Different idea for independent doubles

One of the drawbacks of independent doubles (IDs) is the regulator changes. Removing a regulator from one's mouth at 100+ feet is something that some people might advise against.

It can also create the false impression that you may be in trouble. A DM once told me post dive that when he saw me drop my regulator from my mouth @130FSW he began moving towards me thinking I may be narc'd and in need of help. He came over to me after the switch and gave me the OK sign which I returned not knowing why at the time. Anyway, I'm going to rig a configuration that eliminates the regulator switches while using my IDs. It could also be used with sidemount.

Gear needed is a second stage that can be connected at the same time from both the right and left ports, 2 on/off inline valves, 2 90 degree elbows, and 2 40" or to suit LP regulator hoses for BM (SM would be shorter); also 2 1st stages with identical IP's. Also 2 overpressure reliefs one for each 1st stage. Since only one second stage is used, a second 2nd stage is mounted on the right hand 1st stage for an octo. For complete redundancy an AIR type inflator can be added to give the diver a third 2nd stage option .

The left side 1st stage is connected to the left side of the 2nd stage by the elbow assembled with the on/off valve . The right tank is connected to the right side of the same 2nd stage the same way. The 2nd stage is necklaced and the LP hoses are routed under the arms. Tank switches are made by turning the inline valves on and off instead of switching regulators.
There maybe a slight reduction in redundancy but the diver still has 2 second stages that can access either tank thru separate 1st stages so the reduction is slight.
The on/off valve and elbows can be seen as weak points but after using both for 5 years without issues, I have confidence in their reliability. Here are some pictures: