Safety check my idea

[Erik Burrows]

Hey gear heads, I'd like some safety-conscious eyeballs on an idea I'm trying out: very extended exhaust ports for my regulator. I'm only a day or so into this project, but from my test pool time, I think it could be advantageous:

The idea is to get annoying bubbles away from my mask and ears, purely for comfort and enjoyment.

The design is so far very simple:
1. Attach corrugated rebreather rubber hose to the exhaust ports of my standard second stage regulator
2. Attach the hose ends to a piece of pipe with holes drilled in it behind my head, lashed to the tank
3. (Not visible above) Cut slots in the bottom of the rebreather hose to allow pressure on the second stage to be ambient, and ease exhalation effort

In my pool tests, I've tried all body orientations, small breaths, and heavy breathing, and while exhalation effort is a bit higher, the concept works: it moves the bubbles behind me, dual-hose-regulator-style, and is much more quiet. There is still much I could do to improve this design (shorten hoses, adjust routing, more/smaller exhaust holes, less hot-glue, etc) but what I'm looking for in this post is:
Does anyone see a reason why this is DANGEROUS?

 

[runsongas]

why not just get a kraken or other double hose reg?

 

[Erik Burrows]

why not just get a kraken or other double hose reg?

The Kraken was my 1st choice, but it's sold out forever...
Then I read that double-hose regs can be quite different feeling, in ways that sounded uncomfortable/annoying to me, so I didn't pursue the rebuilt classic regs.
I started with the "extended" exhaust part for my Atomic reg, which was an improvement. Another option may be just very-extended exhaust ports, rather than full wrap-around.

 

[runsongas]

your concept is similar to the anniversary mistral from 2005, but that ended up being fairly unloved.

 

[-JD-]

I had the same idea stewing away in the back of my brain for a couple of years. Hadn't gotten around to it ...

Glad you are giving it a go!

I guess my one safety "note" is that you aren't going to be donating that. Since this is tech, if your group standard is primary donate, you have to resolve the difference. Of course if you dive with RB folks, every one may be a little alarmed at your gear failure mode.


Can you clarify exactly where the slots are?

 

[crofrog]

Higher exhalation pressure can be dangerous… I’m assuming you’re not tech diving that…

 

[Erik Burrows]

I had the same idea stewing away in the back of my brain for a couple of years. Hadn't gotten around to it ...

Well the more I play with it, the more I like it. Today I tried replacing the exhaust pipe (white PVC pipe) with one with lots of little holes all around, instead of a few big ones. The noise level was further reduced, and I didn't feel like I had to keep one side facing "up".

Can you clarify exactly where the slots are?

I cut a oval slice out of 4 of the hose "ribs" on each side on the bottom (side aligned with the bottom of the reg), about 1.5 inches long each, two "ribs" apart. Just a shot in the dark at how much would be enough to keep the second stage from free flowing (which it does without these cuts), without having so many holes that it bubbles up around my face. So far, this is working well.

 

[Erik Burrows]

Higher exhalation pressure can be dangerous… I’m assuming you’re not tech diving that…

Can you elaborate? How much is too much, and what are the warning signs?

Currently, I've only taken it in my pool. The exhalation pressure feels a bit higher than without the hoses, but not so much that I think I'd even notice if I wasn't paying attention. I haven't felt any excess strain on my lungs or diaphragm, but I haven't taken it for any distance yet.

 

[crofrog]

Can you elaborate? How much is too much, and what are the warning signs?

Currently, I've only taken it in my pool. The exhalation pressure feels a bit higher than without the hoses, but not so much that I think I'd even notice if I wasn't paying attention. I haven't felt any excess strain on my lungs or diaphragm, but I haven't taken it for any distance yet.

Exhalation effort contributes to total work of breathing could contribute to hypercapnia and you really need a ANSTI breathing machine to test the modifications to understand what effect they're going to have at higher RMV at depth.

 

[Bierstadt]

Exhalation effort and risk of forcing a freeflow from bubbles in a pipe creating suction. Your solution looks pretty nicely done, but you'll need to fully account for both issues before trusting it.