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Post by luis on Sept 1, 2022 20:12:06 GMT -8
It all depends who you talk to. Moving the noise behind the diver’s head helps a lot, specially not having bubbles around your ears. This is the case for a lot of divers, but not all. I have heard reports from some divers that consider some DH regulator are rather noisy, even do, the noise is behind their head. A local friend of mine thinks his DH with metal cans is noisier than his single hose. And he is wearing a hood up here. Then comes the most important question (at least important to me): what do the fish think? Well, considering that rebreather divers can get closer to marine life than even us, double hose divers, I think that answers that question. I am not ready to go to a rebreather just to get closer to marine life and get better pictures, but I am willing to try a few other things. And this exhaust silencer, is at the moment my best solution.
Yes, I think it makes a difference when I am approaching marine life to take pictures, but I have no way to quantify that. It is just an impression.
As I mentioned above, switching gases and therefore to and from my modified Argonaut was a real contrast in noise level. And just where the noise was coming from. Being down past 150 feet on my double hose was actually very soothing. That must have been an amazing experience, being at that depth. I have also noticed that I can get much closer to fish since diving the DH. If the silencer cans can get you even closer, then that’s really cool. Yes, it was a great experience. I have been to 200 ft or close to it a few times in air, but doing it with helium is a totally different experience. In clear warm water I tend to keep a fairly clear head, even close to 200 feet. But using Trimix with 50% helium, allowed me a very clear head down to over 300 feet. Also, the lighter gas (lower density) made the work of breathing a dream. Helium is not only non-narcotic, but by reducing the work of breathing it dramatically helps reduce any CO2 build up. CO2 is many times (like 25 times) more narcotic than nitrogen or oxygen. I haven’t started talking about my improved venturi and reduced work of breathing yet… I will get to that later. Another interesting observation is the effect of the lighter helium on the position of my right cylinder as compared to my left cylinder filled with Nitro 32. They were both filled to the same pressure. It is also interesting to point out, that as far as I know, I am the only modern technical diver certified to dive Trimix with a double hose regulator. Just a little trivia information. Yes, Cousteau did use helium (I don’t think he used TriMix) in the Britannic, but Cousteau normally didn’t need a certification. About the exhaust silencer, well I still have the inhalation noise to deal with, so it will never be a quiet as a rebreather. But it used to be that my exhaust was louder than the inhalation, not anymore. Cutting down the inhalation noises is a different story. BTW, When I leave my camera behind, fish always come closer to me. They must really know when I want to take their picture… Without a camera, I have had fish come to my mask and look in…
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Post by antique diver on Sept 2, 2022 5:50:56 GMT -8
I haven't been near 300', but I enjoyed reading about your experiences with it. Also like the exhaust diffuser!
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Post by luis on Sept 2, 2022 7:51:29 GMT -8
Thanks Bill,
As I mentioned, the use of helium in the TriMix, makes all the difference.
I have been wanting to try my Argonaut in this configuration, for deep diving. The use of a single cylinder on the back with a side mount cylinder, with the LP hose cross-over, gave me the advantages of independent doubles, or the flexibility of always breathing from the DH, without switching regulators second stages.
The only downside (IMHO), is that there is extra real-estate on my back for a second cylinder, that is not being used, but it is hard to reach those valves, so I am OK with that. And not having to carry doubles out of the water is a side benefit.
I don’t have many opportunities of doing these types of dives, but I will always have the option. It doesn’t require any special manifolds or special equipment.
The concept of an exhaust silencer is not new. The implementation is what becomes is a bit more of an issue.
I do know of at least one European Navy using a semi-closed rebreather with an exhaust silencer. The US Navy uses closed circuit rebreathers.
In a semi-closed rebreather, it is a bit easier because you are just dealing with about 1/3 of the exhaust on every breath... roughly...
I have copies of about 10 different patents for a number of exhaust silencers, from big attachments to the exhaust of a regulator, to even a hood where the exhaust is channeled into many little bubbles. Most of the patents are very old and none of them resemble what I am doing, but similar principle.
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Post by snark3 on Sept 2, 2022 13:05:49 GMT -8
Luis- Is this a record depth for an Argonaut? If not do you know what the deepest an Argonaut has been?
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Post by luis on Sept 2, 2022 15:34:10 GMT -8
Luis- Is this a record depth for an Argonaut? If not do you know what the deepest an Argonaut has been? I am fairly certain that this is the deepest the Argonaut Kraken has been. It is certainly the deepest that anyone has shared. It is also probably some of the deepest any DH has been, but I don’t know for sure. I didn’t think about it until you asked. With your question, I decided to do some research about deep dives with a double hose. I know the Cousteau teem used DH regulators during Conshelf III, but those were very dedicated push-pull regulators to recycle the helium. For the episode “The Coral Divers of Corsica, Episode 32 of 37, Jacques Cousteau Odyssey”, I believe they went as deep as 330 feet. www.youtube.com/watch?v=0g9JQIWw6_ICousteau and his teem took double hose regulators to the Britannic. The ship was found lying on its starboard side at a depth of some 390 feet (119 metres). I do not know how deep they took those regulators, but I don’t recall them going to the bottom. hmhsbritannic.weebly.com/1975-6-cousteau.html“The gas mixture used by the deep divers of the Cousteau team was Trimix 14/54 (Helium 54%, Oxygen 14% and Nitrogen 32%).” That is very close to what I used. The Andrea Doria is another wreck that has been explored with DH regulators. The depth range for the Andrea Doria is from 160 to 250 feet.
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Post by SeaRat on Sept 2, 2022 16:56:14 GMT -8
In his book, World Without Sun, Edited by James Dugan (Harper & Row, Publishers, New York, Copyright 1964), Cousteau wrote: The Cousteau team use La Spiro Royal Mistral regulators on 4-cylinder scuba, and their Deep Cabin habitat was at 85 feet. They started at 85 feet, when to 300+ feet, then returned to their cabin at 85 feet, where they were saturated. They did this using their 4-cylinder tank system, but had to make an axchange whereby fresh tanks were brought to them with scooters. They exchanged tanks by changing their Mistral regulators from one tank to the next, thereby maintinging they full-face masks and communication system on their face. This is how they were equipped during that dive: 0617ABC6-1BD6-46B2-A933-AF654A2C8DD2 by John Ratliff, on Flickr Luis, I think your dive with the Argonaut regulator is a record for surface-to-surface diving without a habitat refuge. John
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Post by luis on Sept 2, 2022 19:11:58 GMT -8
I should point out that the type of dive I did, is commonly done now-a-days by tech divers using somewhat standardized procedures and equipment. I used many of the same procedures, but I used my preferred equipment and a modified configuration, which I personally like much better.
The only thing unique or should I say the primary difference is the use of a DH as a primary regulator. That required a number of small changes, but it is still compatible as a dive team member.
I don’t expect a lot of divers using my same setup, but I still consider it as a very reasonable alternative, with a number of benefits… A personal preference…
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Post by luis on Oct 18, 2022 11:59:50 GMT -8
I own one of those full-face masks. This picture was almost 15 years ago. I don’t find that mask very comfortable.
I have several other (more modern) FFM that I have tried with my DSV. I will posting about some of that test in the future.
My post over in ScubaBoard generated a bit of a debate about the standard deco tank position. Some talk about “left lean, right rich” versus side mount configuration with bottom gas on the right with the long hose for gas sharing, etc. It was a bit of an interesting debate and to some degree I totally see the value to some standardization. But there will always be tradeoffs between standardization and possible improvements or just personal preferences. Here is a link to the thread. scubaboard.com/community/threads/deep-dives-with-argonaut-double-hose-305ft.624643/It can be interesting if you are into technical diving.
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Post by luis on Oct 18, 2022 12:17:04 GMT -8
I have couple of more subjects related to my setup for these dives. I was going to take a long pause in light of Bryan’s passing, but I decided to post since I had most of the writing done from before. One subject, is the performance improvements I have been working on, by optimizing the venturi flow (including the new flow diverter in the DSV and the improved venturi adjusting blocks). My last planned subject will be the cross-over connection and how I controlled my back-gas (using pneumatic lock). When I designed the HPR second stage part of the design considerations was flexibility and adjustability, as well as backwards and forward compatibility with vintage DAAM, RAM and the future 2 stage replacement (now known as the Argonaut Kraken). At the time we didn’t have a mouthpiece with a flow diverter, therefore we had to limit the amount of venturi flow assistance, but I always planned on incorporating a new mouthpiece with a flow diverter. I needed the ability to adjust the mount of venturi flow. From another post: Now we have my new DSV and I now have optimized the flow diverter for the DSV. Therefore, I can push the limits on the venturi flow assistance. Below are pictures of my new flow diverter. The new flow diverter does not allow any blow-by past the mouthpiece, therefore allowing the maximum possible venturi flow assistance. The flow diverter actually seals around the perimeter of the inner tube and it has a vane directing all the flow to the diver. The designed called for an interference fit, therefore to assemble it into the DSV it required a flexible material. The 3D printed units are made out of TPU (a flexible plastic, almost like an elastomer). I got help from james1979 with the 3D design of this diverter and (most important) on learning how to use FreeCAD so I can do my other designs. Looking at the flow diverter into the mouthpiece. Inlet side of DSV and flow diverter.
Exhaust side of diverter.
Some 3D printed flow diverters, before I installed them.
Here are pictures of my new 3D printed bleed-air port blocking device. Notice they can be turn around to allow more or less (down to zero) bleed-air out of the side ports.
I am using a tapered hole and counter sunk screws. The holes are offset just enough so that tightening the countersunk screw creates wedge effect due to the ramp in the hole and the screw. When tighten the screws, the stop pushes sideways against the second stage locking and sealing the bleed-air ports.
This is the configuration I use for maximum venturi flow. Notice that both bleed air ports are fully blocked. The notched ramps are facing out.
This is the configuration I would use with the old stock flow diverter to provide a manageable venturi flow. It is not the optimal, but it is good for must divers.
This is looking into the horn. Notice both bleed air ports are fully blocked.
This configuration provides exceptional venturi flow. This configuration can only be used with the new flow diverter installed in the DSV. With any other mouthpiece, the venturi flow will produce a lot of gas blow-by and out the exhaust. With the vintage curve mouthpiece (no flow diverter) it would often produce an uncontrollable free-flow out the exhaust.
With the new flow diverter, the combination makes for a sweet breathing regulator at any depth.
Next, I will talk about the cross-over connection and how I controlled my back-gas (using pneumatic lock).
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Post by vance on Oct 18, 2022 14:38:40 GMT -8
Back-gas is a common problem for a lot of drysuit divers (like having to pee all the time for us older guys). I get around it by using a wetsuit!
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Post by SeaRat on Oct 18, 2022 14:39:27 GMT -8
Luis, I really like what you’ve done with the DSV Mouthpiece diverter. It reminds me of experiments I did with the Healthways diverter, which was a round, flat plastic piece fitted into the Healthways mouthpiece that diverted their Gold Label Venturi flow into the diver’s mouth. The mouthpiece itself was too small, something Healthways never corrected. I tried this configuration without the non-returns in the mouthpiece, and it still had blow-by into the exhaust. I found that returning the exhalation non-return valve allowed maximum Venturi air into the mouthpiece without blow-by. But the diameter of the Healthways mouthpiece was still too small. So, with my modified Trieste II regulator, I used a USD curved mouthpiece, with a Healthways diverted glued into it. That worked very well, except that on one dive years ago it became dislodged, adhered to the USD intake mushroom valve, and effectively shut off air flow completely. I simply completed the dive using my MR-12 octopus. But then, when your first DSV Mouthpiece came along, I replaced the modified curved mouthpiece with your DSV mouthpiece and have been happy ever since. Now, with this innovation, you have refined the concept even further. It looks like a wonderful addition to double hose diving. IMG_1456 by John Ratliff, on Flickr John
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Post by vance on Oct 18, 2022 15:00:32 GMT -8
I am constantly dealing with this issue. In my modded regs, the position of the second stage in the box, the angle of the primary air jet, the size of the primary jets, and whether one needs no, one, or two secondary jets, are all critical.
As you say, a DSV with its baffle will tamp down a too strong venturi. But, using a DSV requires a stronger venturi to achieve the desired performance than you could use if you are designing a second stage for a regulator using a standard mouthpiece w/o a baffle.
So, as I have found out over time, it all depends!
This is not criticism. I understand that this thread is about optimizing the DH regulator to perform at extreme depths. I am commenting only because I relate to this issue, and find this conversation very interesting and helpful.
There are a few of us who are grappling with venturis, how to tune them, and in particular, ways to make them adjustable.
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Post by luis on Oct 18, 2022 16:41:26 GMT -8
hi vance, I had to look up what tamp down means... sorry. The flow diverter does not suppress (tamp down) the venturi at all. It just redirects the flow into the divers mouth. It does allow better control of the flow (magnitude and direction). I really like your first paragraph. I always said that actually designing a single stage regulator from scratch is actually a lot harder than a two stage. With a two stage you have a relatively constan air pressure into your demand valve. All the performance is driven by the demand valve design. With a single stage you have more variables during the dive. Analyzing a multy-path gas flow is very tricky. But, I am guessing that you are doing a lot more trial-and-error approach than much analytical design work. BTW, my goal is to optimize my regulators for all depth, not just extreme depth. My goal is design a regulator for all depth and all gas mixes. The interesting thing is that at the extreme depth I was using a much lighter gas. The use of helium (50% in a couple of the dives) reduces narcosis by reducing the exposure to nitrogen. But, even as important (or more importan) is that it reduces narcosis by reducing the amount of CO2 produced. CO2 is many time more narcotic than nitrogen or oxygen. Yes, the exhale amount of CO2 is minimal, but that minimal amount is enough to cause a very high narcotic effect. Therefore, it has been proven that by reducing the "work of breathing" (or any work for that matter) the CO2 is reduced and it's narcotic effect. On some deep dives the use of DPV is imperative to reduce the work load, etc. One tip on venturi effect (seat of the pants approach) is to calculate and control the flow area of the jet shooting down the horn to the bleed air port. The flow area is one of the most important parameters that you can control (other parameters like bends in the flow and transition ratios are important, but totally secondary, minor effects). Also making things adjustable always help with anything like this to account for minute variations that can cause significant changes. Another thing to keep in mind is that venturi flow will change with gas density. Therefore, it changes with depth. The flow resistance will increase with density, but the venturi will also increase. And, they are not proportionally equal so they will not compensate for each other. And to complicate everything even more, a breathing cycle is not constant flow. A sine wave is a reasonable approximation. So the inlet flow normally goes from zero to a peak and back to zero. The flow is dynamic in two different ways... I am having a real hard time expressing this. The dynamic flow is constantly changing... I just hope you are having fun... And I hope what I wrote makes sense.
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Post by SeaRat on Oct 18, 2022 16:59:45 GMT -8
This is one of the better papers I've seen as an explanation about CO2 and narcotic effects. www.tecvault.t101.ro/Carbon%20dioxide,%20narcosi%20and%20diving.pdf This appears to be a compilation of different papers on the medical effects of diving, possibly from a symposium, but that is not listed. The first paper, "CARBON DIOXIDE, NARCOSIS, AND DIVING, BY JOHNNY E. BRIAN JR., M.D." is the one I was looking at, but the others are also interesting. That same paper is referenced by GUE on their website: www.gue.com/carbon-dioxide-narcosis-and-divingJohn
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Post by vance on Oct 19, 2022 8:18:48 GMT -8
Hi Luis,
I always read your posts concerning the science involved in making regulators work, with interest. Your explanations above are pretty dense, but clear enough.
As far as my own work with making and or modding parts for regulators goes, I am not inventing anything. Some might call a couple of ideas I've implemented novel, but they are admittedly simple hot-rodding. I have not contributed anything original to regulator design or development. Perhaps I can take credit for some refinement, but I have only accomplished what a car enthusiast might by installing disk brakes on a Model A Ford. Adding an improvement or safety feature to an obsolete design might be innovation, but not invention.
I don't need a lot of data or preliminary testing to make a very workable second stage, an HP port for a J valve, a single stage to DH conversion, and the like. That's already been done, and data is readily available thanks to you and others.
I incorporate the ideas and parts I need or like (or already have!) from existing designs. For example, my second stages depend on elements from several different second stages, such as the Trieste lever double bend foot, the single hose style castle, USD DAAM/RAM dimensions, and USD poppets and springs. In a couple of my conversions, an HPR would have worked well, but I wanted the challenge of making my own. This takes a little trial and error, but mostly from the fabrication side, not so much getting the thing to work well when it's done.
Where I have gotten into no man's land on a project is, as you said, the single stage regulators. This requires much more trial and error to achieve a good result in terms of venturi, bleed jets, air directors/nozzles, and the like. These can be lung-busters if you aren't careful. For example, the single stage DAAM (SSAM) nozzle will need more work on the air jetting. It needs a wide range of adjustability in order to simplify finding a suitable starting point and working toward an optimal venturi.
BTW, you said above that the DSV doesn't tamp down the venturi, but simply directs the air flow into the diver's mouth. What I was talking about is how a regulator that free flows uncontrollably with a regular US Diver's mouthpiece often does not when the DSV mouthpiece is used. In this case, the air isn't directed into the diver's mouth, the free flow doesn't occur. Others have noted this, and have used the DSV to control a regulator's tendency to freeflow.
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