Second stage connection

[AfterDark]

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

Yep I am definitely a survivor and as a result have years more life and diving experience as well as hours diving then you do.

 

[GJC]

Pricey, but wouldn't this be simpler than having to manage 2 gas cutoffs and having 2 hoses to your second stage?

Gas Switch Block

 

[GJC]

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...

Do the tanks drain equally or does one drain faster than the other?

 

[AfterDark]

Pricey, but wouldn't this be simpler than having to manage 2 gas cutoffs and having 2 hoses to your second stage?

Gas Switch Block

WOW pricey is the word! For me way too much money, especially when I already have everything I need and have been using it all except the 2nd stage AIR for a at least 5 years. I used the AIR for a few years as a primary reg until it developed a slight free flow that got worse. I didn't want to mess with it and still don't, it looks to complicated and difficult to work on so, I put in a box where it sat until last year when I found someone that could service it and had it serviced. As soon as I'm done painting my 2 steel 50's I'll fill 'em and setup them up like the 1st picture in my post. It'll be my solo rig and I'm thinking the 50's connected with my old cheater bar would work well with my double hose regulator as a "twin" set which is what they where in 1965 when they were made.

As you can see in the picture of the 2nd stages the on/off valves will be well.......right in front of my face! Just reach up and push up on is in the direction of the air flow towards the 2nd stage, can't miss. Hold both valves at the same time one in the fingers of each hand, inhale, push one up the other down as desired, exhale, inhale, dive.

 

[grantctobin]

Yep I am definitely a survivor and as a result have years more life and diving experience as well as hours diving then you do.

Evidently these years of being able to continue to breathe haven't taught you much in the way of failure modes, statistical bias, or the ability to have a discussion without resorting to "I'm still alive and thus your opinion is invalid" attacks. Of note, if you don't maintain that clusterfhcuk of shutoff valves around your neck, one of them will fail and continue to flow even when "closed."

To confirm, rather than:
"adding an isolator manifold" of four static o-rings and a seat and removing a HP hose, SPG, and two dynamic O-rings (as well as the "need" of the swivels on your first stages)
OR
Being comfortable (or diving with a group that is comfortable a la not the divemaster interaction at 130' ) with you switching regs on a non-manifolded setup

You're chosen:
1) a unicorn reg
2) two elbows (2 static o-ring each)
3) two shutoff valves with two static and 2 dynamic o-rings each
4) an additional LP hose
5) a donation reg that you're not actively using as an octo on your right side
6) potential loss of ability to turn off left hand bottle because of its angle behind your skull
7) and considering adding an Air2 because you think it increases redundancy
And all of the above in addition to yoke first stages and your five after market swivels on your first stages?

Just making sure this is laid bare before someone attempts to mimic your setup and hurts themselves.

 

[AfterDark]

Its modern replacement - the D420...

There is an OEM somewhere that makes what was the HOG "Switchback"....

The Poseidon XStream (just turn it over)

So the D420 can be setup like the AIR in my picture and is of current manufacture?

 

[happy-diver]

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:


View attachment 674576 View attachment 674577 View attachment 674578

@#$%^&*(&&^%$# Genius!

Ultra Magnificent!



grantctobin go take your bs survivorship bias here and play some handsies with the other ZERO EXPERIENCE cultists

The Human Diver - Counter-errorism in Diving - Home Page

 

[rsingler]

So the D420 can be setup like the AIR in my picture and is of current manufacture?

Yes. It requires only a second 11.420.102 hose connection installed in place of the blank plug on the other side of the case.

Part #5 above.

 

[AfterDark]

Evidently these years of being able to continue to breathe haven't taught you much in the way of failure modes, statistical bias, or the ability to have a discussion without resorting to "I'm still alive and thus your opinion is invalid" attacks. Of note, if you don't maintain that clusterfhcuk of shutoff valves around your neck, one of them will fail and continue to flow even when "closed."

To confirm, rather than:
"adding an isolator manifold" of four static o-rings and a seat and removing a HP hose, SPG, and two dynamic O-rings (as well as the "need" of the swivels on your first stages)
OR
Being comfortable (or diving with a group that is comfortable a la not the divemaster interaction at 130' ) with you switching regs on a non-manifolded setup

You're chosen:
1) a unicorn reg
2) two elbows (2 static o-ring each)
3) two shutoff valves with two static and 2 dynamic o-rings each
4) an additional LP hose
5) a donation reg that you're not actively using as an octo on your right side
6) potential loss of ability to turn off left hand bottle because of its angle behind your skull
7) and considering adding an Air2 because you think it increases redundancy
And all of the above in addition to yoke first stages and your five after market swivels on your first stages?

Just making sure this is laid bare before someone attempts to mimic your setup and hurts themselves.

I know, and if I didn't have 3 rotator cuff ops and could scratch the back of my neck, I'd use isolator valves but since I can't, I do what I can. I also don't have the strength to handle doubles on a manifold on land, loading/unloading into the car, putting them in the tank to fill them so, again I do what I can, handle them separately like it was a sidemount rig. I can carry each tank to the water and set them up on my wing at the waters edge. ID's give me the air I need in a form I can handle. So thanks again for the advise, I wasn't seeking it but knowledge is good. I've managed risk in my life for many decades quite successfully from a survival perspective so I'll stick with what works for me.

I've been using those CF valves for 5 years on my 156's and 109 now with 0 issues and if one goes that's what ID is for the other tank is used to end the dive. If both go at the same time well that's a bad day indeed.

 

[grantctobin]

@#$%^&*(&&^%$# Genius!

Ultra Magnificent!



Hey grantctobin go take your bs survivorship bias here and play some handsies with the other cultists

The Human Diver - Counter-errorism in Diving - Home Page

lol thanks Barrett