Safety check my idea

[Subcooled]

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:
View attachment 735407
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?

You should add one way valves on both sides of that corrugated hose.
A demand valve demands an underpressure to operate.

 

[Tracy]

My guess without actually trying it would be that it will increase exhalation effort. This will increase work of breathing causing higher than normal CO2 buildup. At nominal depths, (less than 3 ATA) it would probably increase your gas consumption. At deeper depths without a fair bit helium, it could easily be the start of some fairly heavy CO2 narcosis.

 

[Subcooled]

My guess without actually trying it would be that it will increase exhalation effort. This will increase work of breathing causing higher than normal CO2 buildup. At nominal depths, (less than 3 ATA) it would probably increase your gas consumption. At deeper depths without a fair bit helium, it could easily be the start of some fairly heavy CO2 narcosis.

What exactly would make exhalation effort bigger?
The size of exhaust holes?

 

[Tracy]

What exactly would make exhalation effort bigger?
The size of exhaust holes?

The hoses route lower than the exhaust tees. If you force air lower, it takes resistance. The hoses are also corrugated, that affects flow. The regs are designed and flow tested to minimize breathing resistance, any modification is probably going to have an effect. These are guesses based purely on looking at a picture online.

 

[Erik Burrows]

My thought regarding the flow of exhalation is that air expelled from the regulator pushes water out of the hoses through the holes both by the tank, but also via the slots cut in the bottom of the hoses. This seems to work, but is definitely an area that could be optimized to reduce exhalation pressure as much as possible.

 

[Jcp2]

My thought regarding the flow of exhalation is that air expelled from the regulator pushes water out of the hoses through the holes both by the tank, but also via the slots cut in the bottom of the hoses. This seems to work, but is definitely an area that could be optimized to reduce exhalation pressure as much as possible.

C370 love it

There isn’t a single hose regulator that will not put bubbles in your face in some odd position, but a DH makes it nearly impossible. I rarely see bubbles with the D420 or any other reg. When I do it’s from moving into a position that puts my mask into the trouble zone, doesn’t happen often...

scubaboard.com

 

[lexvil]

You don’t want water in the hose, I had the issue with a Kraken and it was amazingly hard to push the water out, you’ll really want a check valve in there, maybe in a tee with a riser which may induce flow once past the check.

 

[Erik Burrows]

You don’t want water in the hose, I had the issue with a Kraken and it was amazingly hard to push the water out, you’ll really want a check valve in there, maybe in a tee with a riser which may induce flow once past the check.

lexvil, this design has the hoses fully flooded at all times. It's not a dual-hose regulator setup at all. Think of the hoses not as part of the breathing loop, but more like gutters for the bubbles. The hoses are perforated at the bottom near the regulator, and the upper vent is fully open, allowing for free flow of water. It just redirects the bubbles around my face and ears.

 

[lexvil]

lexvil, this design has the hoses fully flooded at all times. It's not a dual-hose regulator setup at all. Think of the hoses not as part of the breathing loop, but more like gutters for the bubbles. The hoses are perforated at the bottom near the regulator, and the upper vent is fully open, allowing for free flow of water. It just redirects the bubbles around my face and ears.

Well carry on, good luck…

 

[johndiver999]

I think it sounds like a pretty cool idea. Not that I am qualified to comment on the safety of it, but if you had a way to dis-connect the hoses from the exhaust port with a good tug, then if you become over-exerted at depth, you just revert back to normal exhaust.