Argonaut Kraken HP seat failure...?

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Fibonacci

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New thread split off the Kraken hose loop flooding issue for clarity...

A quick summary:
I had a failure of the HP seat in my near new Kraken on the morning of Day 3 of a 9 day PNG dive trip.
Up till then it had performed perfectly and caused a great deal of interest from the other divers.
I was loving the start of the whole DH experience, so it was very annoying to have it fail before I got the chance to fully explore DH diving.
On my return home I returned the Kraken and the DSV to the US at Bryan's request... no local service available in Australia.
He serviced the Kraken and replaced the HP seat for free which was good but the returned parts showed a very strange wear pattern where the HP Volcano Orifice had engraved the HP Seat so far off centre it hit the inner metal support for the pin, venting HP air through to the loop.
Kraken HP seat failure detail.jpg

There are some white shadows/darker discoloration on the seat face but the damaged indent is where the material failed. You can see the indent is considerably off centre to the pin aperture, and appears to have been sheared at an angle.
I have pulled apart quite a few Conshelf XIV and Cousteau SEA's and never seen this sort of very off-centre wear pattern. Bryan was at a loss to explain why this would occur, which makes me feel uneasy about it re-occurring.

Hopefully Luis will copy his content here from the other thread so both issues can be discussed separately.
 
I don’t know what does the first stage seat has to do with the exhaust hose, or why did you posted that in this thread. In any case, I am actually seeing two different things on the pictures of that seat. The indentation from the volcano and a crack on the surface of the seat material. It is just a picture, so please let me know If what I see from the picture is not correct.

I am pointing to the indentation from the volcano orifice with a red arrow and to the crack with a green arrow.

I also added a red circle on top of the indentation from the volcano orifice. You may notice that the crack doesn’t for a good circle. It doesn’t even has a smooth curve.

This crack is definitely a defect or a malfunction. Again I do not know where Bryan gets his seats other that they are being made by a Scuba parts manufacturer/ supplier. I have seen bad seats before.


dive-at-cozumel-with-argonaut-x2-jpg.484037.jpg




The red circle is covering volcano orifice indentation:

dive-at-cozumel-with-argonaut-5-jpg.484038.jpg
 
He serviced the Kraken and replaced the HP seat for free which was good but the returned parts showed a very strange wear pattern where the HP Volcano Orifice had engraved the HP Seat so far off centre it hit the inner metal support for the pin, venting HP air through to the loop.

View attachment 484108

There are some white shadows/darker discoloration on the seat face but the damaged indent is where the material failed. You can see the indent is considerably off centre to the pin aperture, and appears to have been sheared at an angle.


That is not what I am seeing in that picture. I will explain.

The volcano orifice can be considered to be a perfect circle.

I highlighted with a red arrow on the left what is obviously the indentation from the volcano orifice. Then a laid a circle to match that indentation. You can see on the right where that indentation has a matching mark.

On the right, the volcano orifice indentation is not as clear, because there is that material fracture (that I pointed with the green arrow).

I look at my “perfect circle” laying on top of the volcano orifice mark, and it look fairly concentric to the seat. That is not a problem.


This fracture is a defect. It falls into the category of infant mortality. I started servicing regulator (at a dive shop “professionally”) close to 50 years ago and I have seen a few of this from several manufacturers. IMHO, I place into the category of "$hit happens". Infant mortality is the reason no one would buy anything from a manufactures that doesn’t have at least an initial warranty (of some reasonable period of time).
As an Industrial Design Engineer, I am sure you are familiar with the term infant mortality.

It is a real shame that it happened when it happened to you! I feel really sorry that it happened at that moment. But, if you are familiar with Murphy’s law (and I am sure you are, all engineers should), you will know that failures rarely happen when it is convenient.

Bryan told me that he has only had two seat failures from this manufactures. One is yours and the other belonged to a good friend of ours from the Philippines. Again following Murphy’s law, the two failures couldn’t happen to a neighbor of Bryan or maybe one of the Argonauts here in Maine that I could have helped. Bryan could help anyone in the US with overnight shipping, but of course it had to happen to someone on the other side of the world...


I know most people don’t have a spare Argonaut or a even a spare back-up regulator. I do and I always carry both an Argonaut and a spare single hose regulator. They have both been used by many friends (sometimes they are instant friends having an issue at the dive site).

I also always carry spare parts on a trip (I organize many dive trips with groups of friends). I am a strong believer that if you have the spare part, you will not need it (the other part of Murphy’s law).


OK enough philosophy this early in the morning…

Good luck and good dives…
 
This fracture is a defect. It falls into the category of infant mortality. I started servicing regulator (at a dive shop “professionally”) close to 50 years ago and I have seen a few of this from several manufacturers. IMHO, I place into the category of "$hit happens". Infant mortality is the reason no one would buy anything from a manufactures that doesn’t have at least an initial warranty (of some reasonable period of time).
As an Industrial Design Engineer, I am sure you are familiar with the term infant mortality.

It is a real shame that it happened when it happened to you! I feel really sorry that it happened at that moment. But, if you are familiar with Murphy’s law (and I am sure you are, all engineers should), you will know that failures rarely happen when it is convenient.
~snip~
I know most people don’t have a spare Argonaut or a even a spare back-up regulator. I do and I always carry both an Argonaut and a spare single hose regulator. They have both been used by many friends (sometimes they are instant friends having an issue at the dive site).

I also always carry spare parts on a trip (I organize many dive trips with groups of friends). I am a strong believer that if you have the spare part, you will not need it (the other part of Murphy’s law).

OK enough philosophy this early in the morning…
Good luck and good dives…

Ah yes Mr Murphy is my constant companion at work :D

This being my first LOB in a very remote area with a DH reg I did indeed carry a spare single hose reg set... Old Faithfull, a Conshelf XIV with Sea Hornet Command Air second stages and a SPG. So I was able to switch to this backup system seamlessly... and not use the usual ancient backup reg set fished out of the bilge that is the norm on most LOB's!

I also carried a comprehensive array of spares <except> spare hose clamps, which I needed early on before I realised the HP seat was spiking IP. 200psi air was being delivered to the DSV mouthpiece then leaking past the corrugated hose Cobra clamps then finally venting out the octo!

So yes, hopefully this HP issue is just one of those rare infant mortality failures and the Kraken is as reliable as all the others are reported to be.

All the best in diving...
 
I too had issues with the IP spiking, resulting in the octopus beginning to free flow as a tell tale sign. The HP seat had similar markings (see photos below). I went through three OEM HP seats in total, over about 130 dives total. Two were brand new and one was a an old spare I had lying around that looked good to the eye, but failed after 2 dives. I dive most days so this isn't a case of the reg sitting in a cupboard for ages. These failures were after Jerrie at DiverdownDH did a full service and rebuild on the reg, including photos, so we can be sure it was assembled correctly since Jerrie is not just some random technician but comes recommended by Bryan (VDH was closed due to covid, and a message on his website directing servicing to Jerrie).

I managed to find a brand new blue Aqualung HP seat and used that for a few dives, before shelving the Kraken about 6 months ago due to high maintenance putting me off (having to clean and dry the hoses all the time), and also switching to side mount. Single hose is just so much less maintenance and much more versatile, plus I don't have to worry about HP seats failing in my Apeks DSTs...
However, this isn't a SH vs DH thread...

In my case I suspect the issue was with the OEM HP seat being lower quality (less durable?) in comparison to the blue Genuine Aqualung seat, though I don't have data to support that yet since I didn't use the reg much since swapping to the Aqualung seat.
Mine is a 2017 model, photos of the latest failed OEM HP seat here:
1664075403579.png

1664075456509.png
 
I have been using Conshelf and Royal Aqua Master regulators for over 50 years and I have seen a few seat failures. To be honest very few considering the sample size, but it does happen.

I design the Phoenix and later the Argonaut/ Kraken intentionally using the most popular seat design in the Scuba industry. The Aqua Lung seat design (geometry fit and function) is also used by a number of Mares regulator. Therefore, the seats are interchangeable.

Just a brief history to trace first stage design. Many of the Mares first stages use the original Voit/ Swimaster design. Mares bought Voit a while back. The early Voit double hose regulators were actually produced by US Divers (now Aqua Lung). That is why the geometry, fit and function of the Mares and Aqua Lung seats are interchangeable. They have the same origin.

So, there are at least 3 suppliers for seats (maybe more) that can be used in an Argonaut or a Phoenix. As I mentioned before, I do not know where VDH/ Bryan gets his seats. I do know that Trident sells after-market seats (they are also black) that will fit Aqua Lung and Mares regulators.

Recently I have also seen some blue (a little different look in the pictures) sold by Northeast Scuba Supply.

I have been using the blue Aqua Lung seat long before I design the Phoenix or the Argonaut and I have had excellent performance and longevity from them. I have the longest experience with the Aqua Lung seats. I have tried the Mares (tri-material seat) and they also seem very good, but I have very limited experience with that seat.

There is no question that Aqua Lung has put a lot resources and research in developing an excellent seat. They have had several iterations of seat design (in close to 60 years), but the newer blue seat is excellent. I am not saying it is better than the others, I just have limited experience with the others.


BTW, I would say that any of the modern seats work better than the original black hard rubber seats. When servicing an Conshelf or a RAM back in the 70’s I often had to try a couple of new seats in a regulator to get a good lock of the IP. When they worked, they were very reliable, but we often got a bunch of bad brand-new seats in the mix. The looked good, but they would not seal well.
 
I have been diving Conshelf first stages for several years. The hose routing suits me (SE). They are inexpensive and easy to find, lightweight, easy to work on, and reliable. I won’t let rare parts failure discourage me.
 
I can't say too much on the technical aspects of these seats but from the photo examples shown. Most if not all of the photos are not genuine parts. Hard to confirm without inspecting but:

The Blue colour seat in the last photo shows a PU material being used. Not the genuine polymer type but near as you can get to a non propriety blend without me disclosing the actual polymer blend. Note the lack of adhesion of the polymer bond to the substraight and the feathering over the edge. Poor crap workmanship copy from Taiwan /China to some backstreet scuba importer in the states.

Incidentally Aqualungs QA for sports products is 10/100 so for every batch 10 in 100 are taken at random and inspected. If one seat fails then a further 2nd sample of a larger quantity is taken. If another single seat fails inspection from the 2nd batch then the whole batch is rejected with no rework allowed.

The earlier photos showing a black colour seat "face on" with the guy with the clean finger nails This illustrates the poor design this seat design really is after 50 years of plugging the same old Yankee design. Note the area between the "contact area" and the polymer mass its huge and does nothing but offer a plug of pliable plastic waiting for a kindling effect fire when used in higher oxygen concentrations
as they are so often used. Poor design back then but good enough I guess. And a good enough reason why getting rid of your original design engineers is a poor management call before you bail out for pastures new at PADI I guess.

First batch of photos again shows a poorly made China copy with an out of design tolerance of concentricity. But what you really need to see in addition is the state of the spring (not shown)
Cause and effect are two sides of the same problem but your seeing just the effect.
Oh and a good example of poor design copied by idiots out of some back street sweat shop
imported into the USA by some scuba shack mom and pop dive shop selling to the great unwashed PADI diver. Take care in what you purchase.

Incidentally I was the author for the US Divers Conshelf XIV Supreme. Manufacturing Inspection and Test Procedures prior to the introduction to the Royal Navy. So its a wild ass guess. LOL Iain
 
https://www.shearwater.com/products/swift/

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