Quick Disconnect on Octo / SafeSecond reg?

[MaxTorque]

And your plan when the switch block or the hose from the block to the FFM fails?

There is a reason the left post is completely separate from the right on a twinset with an isolator in between. You are negating the whole point by plumbing both sides into a switch block. And seem to really want to make this complicated with 3+ different ways to get gas.

If the FFM fails you take it off and switch to an alternate - that's it, period, you're done

What we are talking about here is a balance of probabilites!

The gas switch block has some potential for gross failure call that "x"
There is some potential failure with the removal of the FFM and bailout to half+reg, call that "y"

What we want to know is X less or more than Y? The problem is that is not a straight forward assement that is easy to make

I'd suggest the probability of a gross failure with a gas switch block that resulted in an incontrolled loss of gas from both 1st stages (on their seperate posts) is really rather small. What would that failuire be? It would have to be on the inlet side of the GSB, and yet affect both inlet sources? Is that realistically possible? It's going to depend on the exact architecture of the GSB itself. I expect (i don't know) that given GSBs are extensively used for commercial surface suppied operations (to allow the diver to bailout into their backup backgas) that they must be reasonably reliable?


All interesting and valid points though, and enough to require significant thought

 

[Blackfrogfeet]

OP, I don't think you're going to find too much validation for your idea on Scubaboard. That being said, you have made up your mind about diving FFM, so I'll just give an opinion on the original question: don't add a quick connect to your 1.5m secondary reg hose. It's totally unnecessary. I can see where your thought process is coming from, you want to have more available courses of action in an emergency. The thing is you don't need more options, you need less. You need the immediate remedy to a problem to be as automated as possible so there is no confusion. Keep that mental flow chart for underwater decision making as linear as possible.

One of the hypothetical situations you mentioned involved diving with another diver who was on an FFM that used a compatible quick connect running out of gas. Now you could potentially just remove the second stage from the long hose and plumb your QC long hose into his FFM and you're good to go. But now imagine if your buddy isn't on the same page as you in a moment of panic. As you go to remove the 2nd stage from the QC and hand it to him to plumb in to his FFM, he gets confused and fully removes his FFM expecting a standard donation. Now your buddy is sitting there OOG with no mask, and you have an LP hose with no 2nd stage on it.

Just keep it simple.

 

[MaxTorque]

Great post ^^^ exactly the sort of stuff i wanted to consider and think about!

Options vs simplicity is a perfect description of the "problem"

And on the FFM, i haven't "made my mind up" about anything tbh. The FFM is simply another tool in the box. There will be some dives where i'll use it, and some where i won't. I have a nice set of Apeks MTX-R's that i can simply swap i for dives where those are more appropriate (anything multi-cylinder or requiring gas switching, for example)