Argonaut Kraken exhaust loop flooding issue...?

I have also posted this over on VDH, and got two confirmations of similar regular flooding events from other Kraken owners but posting here more broadly as the similarly designed drop-in DBE is also likely to be affected.

I had issues on a recent dive trip to PNG when the exhaust loop on my Kraken would occasionally flood in specific conditions... body horizontal, head slightly down, paused after breathing out.
Could hear a 'glick-glick-glick' as water came in... occurred about 1 in 5 breaths in that position
Hoses, diaphragm, can and mouthpiece exhaust valves were all fine.

The exhaust loop flood first occurred on a night dive when I was breathing softly, marvelling at how the DH reg allowed me to get much closer to the tiny shrimp I was photographing.
Suddenly it became almost impossible to breathe out without a major effort... very disconcerting!

I suspect the can exhaust valve is lifting off a little allowing water in because with body horizontal and head down the can exhaust valve becomes the highest point in the system.
IMO the exhaust valve should have some ribs added to increase stiffness to tune the 'break point' for the volume of static air in the hose. Simple metal-off tool mod.

Here's something I prepared earlier adding a tapered triangular 0.5mm rib to the existing valve

 

I have had a similar problem with the old, original Healthways Scuba double hose regulator. This regulator has a very different exhaust system, and Healthways recognized an exhaust "imbalance" early in production, and so put in a second valve, a small duckbill inside the exhaust horn. The problem was that the differential in pressures held the exhaust diaphragm (see the drawings and photos below) did not seal in a head-down position, and water would glob, glob into the exhaust hose.

I suspect that you are having the same issue, but because the mushroom valve used in the Kraken is very light and sensitive, and in this position could lift off the sealing surface as you describe, and allow water inside. This allows very easy exhalation, but may also allow water into the hose in certain circumstances. Since I haven't seen this regulator, that's all theoretical, but can be easily determined in a pool by reproducing the body position and seeing whether it happens again.

I have dived the Healthways original Scuba design without the duckbill in the exhaust loop, and it is the easiest exhalation of any double hose regulator I have ever used, except in that head-down position. I have found that in the head-down position, if I exhale slightly while there, the water entry is minimal, and in any case it is also easily cleared by simply exhaling (although for this breath or two, it is harder breathing).

Saying this, I have newer Healthways double hose regulators, a Nemrod Snark III, Dacor, and a Sportsways Hydro-Twin double hose regulator, that have mushroom exhausts which do not do this.

I'd be interested in what Herman has to say about this report.

SeaRat

PS, I'm happy to hear you have discovered the wonder of using a double hose regulator for underwater photography, especially macro photography. I got some very interesting photos of very skittish small fish this summer in the Clackamas River.

 

Check that the exhaust valve is in good shape and the arrow head in the stem is properly seated.

It is not uncommon to get a little leak or a few drops of water back past the exhaust valve (just like in a single hose exhaust), but flooding is a malfunction and it should never happen in any position.

Some water drops leaking back while you are exhaling is common on any type of exhaust, but flooding is not.

I have hundreds of dives using several different Argonauts (and hundreds of other divers do to) and before that with the DBE and I never had the exhaust fully flooded. A little bit of water from small leak yes, but fully flooded means an exhaust valve malfunction.

You may have had debris temporarily caught under the valve or the stem might have been partially unseated.

You may want to just replace the exhaust valve.


One other thing that I often do is put a small drop of silicone seal caulking under the arrow head in the stem and make sure the stem is fully seated (I also do this on the mouthpiece valves). I do this because I use a high velocity blower to dry my hose loop and exhaust after a weekend of diving. I am afraid the flow velocity could partially dislodge or unseat the valve. This is not required, but it guaranties that the mushroom valves are always properly seated. You may want to try this first if you don't have a replacement valve handy (where you live in Australia).

 

I was having the same problem on a recent dive. Changed out the O-rings in the DSV and the loop is dry as a bone. The water enters the purge hole and the hard breathing and gurgling begins. Easy fix.

 

Not a drop of water in the mouth piece for me but exhaust hose gets water in it from time to time. I’ve had the not fully open thing happen with the first DSV’s which was to loose and could easily move, later o rings fixed that but the exhaust leak is a different thing.

 

If the exhaust leak is more than just a few drops (or very small leak), I would try a new exhaust valve or check that the exhaust valve is properly seated. You could try the little silicone seal in the stem (under the arrow head) as I described in my earlier post.

 

I did change the valve but with the intermittent nature of the problem it’s was never apparent that it did or didn’t help, I’m going to see if I have another valve and give that a shot along with the silicone sealer thing.

 

I would definitely try the silicone seal on the stem below the arrow head. Just a little bit, just to hold the valve properly seated.

It is very possible that with manufacturing tolerances that the valve stem may fit loosely into the hole and the valve may not be always fully seated if it is loose. A tiny bit of silicone seal with take care of any loose valve.

I have seen this on a few mouthpiece valve cages, that the tolerances of different valves and the cages made for a loose fitting valve. The valve was loose and partially floating.



The mushroom valves that Bryan is having made are basically a proven standard design. The only thing different on this valves is the dimension of the stems to fit the hole on the support spider. The diameter of the valve is a fairly standard size, so it is very possible that the valve from a plastic case single hose regulator would fit just the same, but I have not tried it. The valves that Bryan is making have always worked fine on everything that I have tested.

 

Lunchtime FEA on the Kraken exhaust valve standard and ribbed version... you can see the stress is dissipated with the ribs and subsequent lower deflection rate.

 

yet I wonder the impact on exhalation effort....