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Post by Fibonacci on Aug 6, 2023 17:01:16 GMT -8
~snip~ Experimental in that in all of my years of diving (since 1984) only double hose regs have failed me. My first failure was a port plug o-ring blowing right after jumping in on a new Argonaut Kraken. Fortunately it blew on the surface and not a little later when I’d have been over 100 feet on the Cayman wall. The second failure was when the duckbill eliminator mushroom valve stuck to the main diaphragm locking the whole reg up and making it unbreathable at 90 feet. That was on the Kraken but now in DA cans and not the plastic body. The third was when a new blue seat came dislodged resulting in a fairly violent free flow during a pool test on the Trieste/Black 50 Fathoms.
All were survivable but a little unnerving and embarrassing since all were either on a dive charter boat or in the case of the pool failure, in front of a dive class.
I guess I sympathize because I’ve had failures that I’ve been fortunate enough to survive. They didn’t have the same fortune and that is sad beyond measure. ~snip~ With all the best original intentions, unfortunately the Kraken has some design flaws... The exhaust valve 'spider' tends to get distorted in production (thick wall injection moulding transitioning to a thin wall) and leaks back into the hose causing a complete flood if you sit head slightly down (as in photographing macro subjects). I had to get a replacement can from Bryan, but the existing seal face may possibly be sanded or milled flat if not too bad. The second major issue is the exhaust valve suction cupping onto the LP diaphragm, leading to randomly variable WOB and hose floods. Mine was particularly bad in this respect, the suction cupping led to noticeable witness marks when the can was split. The solution is to fit an Apeks exhaust valve AP1429 with integral standoff rib, this is a robust fix but should have led to a global alert to all existing customers, and introduced as a running change on all future production. The third issue I have faced is VERY short service life on the HP seats, it appears the OEM fitment was Trident seats but even replacing them with AquaLung blue HP seats they only lasted around 20 dives before the IP spiked. Mine is a 2017 model and it seems that this batch only suffers from the failure mode, others have contacted me with similar stories of very short HP seat life from brand new.
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Post by SeaRat on Aug 6, 2023 17:57:12 GMT -8
~snip~ Experimental in that in all of my years of diving (since 1984) only double hose regs have failed me. My first failure was a port plug o-ring blowing right after jumping in on a new Argonaut Kraken. Fortunately it blew on the surface and not a little later when I’d have been over 100 feet on the Cayman wall. The second failure was when the duckbill eliminator mushroom valve stuck to the main diaphragm locking the whole reg up and making it unbreathable at 90 feet. That was on the Kraken but now in DA cans and not the plastic body. The third was when a new blue seat came dislodged resulting in a fairly violent free flow during a pool test on the Trieste/Black 50 Fathoms.
All were survivable but a little unnerving and embarrassing since all were either on a dive charter boat or in the case of the pool failure, in front of a dive class.
I guess I sympathize because I’ve had failures that I’ve been fortunate enough to survive. They didn’t have the same fortune and that is sad beyond measure. ~snip~ With all the best original intentions, unfortunately the Kraken has some design flaws... The exhaust valve 'spider' tends to get distorted in production (thick wall injection moulding transitioning to a thin wall) and leaks back into the hose causing a complete flood if you sit head slightly down (as in photographing macro subjects). I had to get a replacement can from Bryan, but the existing seal face may possibly be sanded or milled flat if not too bad. The second major issue is the exhaust valve suction cupping onto the LP diaphragm, leading to randomly variable WOB and hose floods. Mine was particularly bad in this respect, the suction cupping led to noticeable witness marks when the can was split. The solution is to fit an Apeks exhaust valve AP1429 with integral standoff rib, this is a robust fix but should have led to a global alert to all existing customers, and introduced as a running change on all future production. The third issue I have faced is VERY short service life on the HP seats, it appears the OEM fitment was Trident seats but even replacing them with AquaLung blue HP seats they only lasted around 20 dives before the IP spiked. Mine is a 2017 model and it seems that this batch only suffers from the failure mode, others have contacted me with similar stories of very short HP seat life from brand new. (emphasis added, jcr) This is one reason I never went for the duckbill eliminator concept (DBE concept). I felt, and continue to feel, that the concept of the duckbill is a better design for double hose regulators, and have one in each of my double hose regulators that can take one. This includes my Mistral (with a Professional Mouthpiece, without non-return valves), my Mossback Mark 3, my Royal Aquamaster (RAM), and my Trieste II. John
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Post by vance on Aug 7, 2023 8:05:36 GMT -8
Fibonacci: "The third issue I have faced is VERY short service life on the HP seats, it appears the OEM fitment was Trident seats but even replacing them with AquaLung blue HP seats they only lasted around 20 dives before the IP spiked. Mine is a 2017 model and it seems that this batch only suffers from the failure mode, others have contacted me with similar stories of very short HP seat life from brand new."
I have heard of the exhaust valve sticking to the main diaphragm on the Kraken, but never before heard of the HP seat problem. I'm a bit confused though. Is it only the 2017 run that suffers from this? I'm guessing the volcano might be too sharp, and cuts into the seat face.
I no longer use the VDH blue silicone LP seat pucks. I've experienced, and heard reports of them coming out of the holder and getting partially stuck into the volcano orifice. They are too soft or too flexible and don't glue well, so I'm sticking to the old style black pucks.
I bought a set of Kraken boxes and will look them over for the defect you've mentioned.
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Post by Fibonacci on Aug 7, 2023 17:25:23 GMT -8
I have heard of the exhaust valve sticking to the main diaphragm on the Kraken, but never before heard of the HP seat problem. I'm a bit confused though. Is it only the 2017 run that suffers from this? I'm guessing the volcano might be too sharp, and cuts into the seat face. I no longer use the VDH blue silicone LP seat pucks. I've experienced, and heard reports of them coming out of the holder and getting partially stuck into the volcano orifice. They are too soft or too flexible and don't glue well, so I'm sticking to the old style black pucks.I bought a set of Kraken boxes and will look them over for the defect you've mentioned.Unfortunately my brand new Kraken HP seat failed after half a dozen dives on a remote area LOB trip to PNG. Followed by repeated hose floods... Really annoying as I loved diving with it and the bubbles behind you really does allow you to approach shy critters or schooling fish more closely. I always bring a spare reg, so continued the rest of the trip using my old faithful Sea Hornet Command Air reg. This was rather embarrassing, as the Kraken DH provoked a lot of interest initially along with the usual comments about "those old double hose regs will kill ya" so there were some knowing smirks from them seeing the SH reg come out later Here's some supporting pics (I've posted some of these before but its useful, to upload again to stay on topic) From some DMs I have received from other Kraken owners it would seem the issue is with the 2017 batch, but hard to get actual data on how many are affected. The pic below shows the OEM Kraken HP seat which I believe was sourced from Trident. Swapping it out to a blue Aqualung HP seat resulted in a much longer life but it still failed after about 20 dives vs 6! Racking my brains to work out what the failure mode could be... my initial thought was that the removable HP Volcano Orifice could be moving about in its bore slightly causing some scrubbing against the HP seat? Dunno... Kraken HP seat failure detail by fibonacci101, on Flickr Kraken valve 1 arrows by fibonacci101, on Flickr Apeks AP1429 exhaust valve by fibonacci101, on Flickr Kraken diaphragm marks 2 by fibonacci101, on Flickr Kraken can 1 by fibonacci101, on Flickr
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Post by SeaRat on Aug 7, 2023 18:01:31 GMT -8
Interesting photos on the Kraken. One of the product safety techniques is to run a Failure Modes and Effects Analysis (FMEA) before manufacturing is commensed on a new design. This is routinely done on tools in the semiconductor industry for their application for CE ratings in Europe. Concerning exhaust systems, here is a drawing I made of the two competing exhausts from U.S. Divers Company, using a duckbill, and Healthways, using the exhaust diaphragm inside the top box. SCUBA vs Aquamaster001 by John Ratliff, on Flickr We discussed here the problems of the Healthways Scuba Delux with a silicone diaphragm causing a total blockage of the exhaust mushroom. Here are some photos from that discussion some years ago. It caused me to abort a dive, and completely change regulators. IMG_1423 by John Ratliff, on Flickr IMG_1417 by John Ratliff, on Flickr I solved this problem by glueing a large stainless nut onto the box so that a complete covering of the mushroom by the flexible silicone diaphragm was not possible. I was using this regulator without non-returns in the mouthpiece, which caused an overpressure to build up and completely block exhalations without that nut. I think that the Aqualung Mentor regulator got around this by designing the bottom box to be deeper and away from the diaphragm. Mentor Parts Diagram by John Ratliff, on Flickr SeaRat
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Post by Fibonacci on Aug 7, 2023 18:22:11 GMT -8
I wish we were able to buy the AL Mentor, seems they addressed all the niggles with existing DH designs including the Kraken! Mulling over the FMEA for the premature HP seat failure issue, I measured the bore where the HP Volcano Orifice sits in a RAM vs my 2017 Kraken and the clearance is definitely greater in the Kraken. Small but measurable. The 3D CAD section below is accurately modelled in this area and you can see the clearance. Granted the 90 Shore A o-ring would tend to centre the Volcano orifice in the bore, but maybe the o-ring plus clearance is allowing excessive axial movement or 'springiness'. Theoretically this could cause the HP Volcano Orifice to scrub or fret the HP Seat under breathing cycles? The Trident HP seats failed much more quickly than the proprietary blue HP Aqualung seats but they both still failed prematurely. Kraken HP Seat Section 1 by fibonacci101, on Flickr Kraken HP Seat Section 1 Detail by fibonacci101, on Flickr
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Post by vance on Aug 7, 2023 19:06:15 GMT -8
I'd try removing the volcano orifice and flattening/smoothing the seating edge a bit. That seat looks cut to me!
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Post by vance on Aug 8, 2023 13:20:10 GMT -8
You should check the bore and removeable volcano diameters to check for excessive play, as you suggested there might be. The interface between hard and soft seats are very off-center.....
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Post by antique diver on Aug 8, 2023 13:45:55 GMT -8
I'd try removing the volcano orifice and flattening/smoothing the seating edge a bit. That seat looks cut to me! Even worse... the cut looks off-center to me. Something isn't lined up properly!
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Post by vance on Aug 8, 2023 14:59:23 GMT -8
I have always thought the Kraken is awesome, and have always applauded the production of a modern DH regulator. I'd love to see more of them. I was hoping Old Mossback's regulator, the SeaWolf, would see the light of day, but it isn't likely unless someone else takes up the mantle.
As I have said in the past, no small producer of equipment can test the product as intensively as a major company must do these days. I know that in the early days of scuba equipment, testing was done via the seat-of-the-pants approach (which meant sell it to consumers and see if it works), but one could do that then. No longer.
That there are issues with the Kraken is not in question. How could there not be?
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Post by vance on Aug 8, 2023 15:09:30 GMT -8
John's photo of his Deluxe shows an early version that did not include a tab soldered to the box that kept the main diaphragm from interfering with the exhaust mushroom. The later ones and all GLs had the tab as shown here: IMG_3953 by Vancetp, on Flickr Some manufactures went to greater lengths to block the interference like this Soviet example: IMG_2967 by Vancetp, on Flickr
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Post by Fibonacci on Aug 8, 2023 16:36:14 GMT -8
~snip~ That there are issues with the Kraken is not in question. How could there not be? I have always admired Bryan Pennington's enthusiasm and drive to get the Kraken DH to limited production against all odds. Kraken DH owners are a small and passionate group worldwide, but with Bryan's tragic passing we have to continue the usual fine tuning (that occurs in any product development process) ourselves. The best way to do this is via open and frank discussion about some issues that have arisen over time, and how best to overcome them so these regs can continue to perform optimally and safely. Good idea to start a fresh thread!
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Post by Fibonacci on Aug 8, 2023 18:35:18 GMT -8
Even worse... the cut looks off-center to me. Something isn't lined up properly!That seems to be consistent, here's a pic of another failed Trident HP seat. Kraken HP seat failure 2 detail by fibonacci101, on Flickr I'm struggling to understand how the chain of fairly tight fitting interrelated components could stack up to be that far out of alignment vs the axis! All other RAMs I've pulled down may vary slightly off centre but nothing like this...
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banana
Regular Diver
Posts: 18
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Post by banana on Aug 9, 2023 5:00:43 GMT -8
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Post by vance on Aug 9, 2023 7:00:45 GMT -8
Yikes! I've had that happen with NOS Voit seats, but not a new blue seat.
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