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luis
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ARGONAUT DSV design information.

Mon Nov 28, 2016 9:28 pm

Note: In this thread I am trying to collect all the technical information on the DSV that I have posted in different places and locate them in one place.


DSV (Dive Surface Valve) style of mouthpiece

Features:

1) Simple design with minimal number of parts to increase reliability and keep production cost down.
2) Closing feature is accomplish by rotating hose / hose clamp assembly. No lever sticking out of the front of the assembly.
3) There is a removable mechanical stop that limits the rotation and gives positive feedback that the DSV is open or closed. The stop also keeps the two cylinder in alignment. The stop is removed in order to disassemble the DSV.
4) Water in the mouthpiece byte tube can be purged before opening mouthpiece. This keeps the loop completely dry.
5) There are traditional check valves (inlet and outlet) on both sides of the mouthpiece, but if the diver purges the little water inside the byte tube, there will never be any water entering either hose that will need purging. Purging by just blowing (or raising the MP above the can) is always possible as with a traditional MP.
6) Mouthpiece was tested as completely water tight. Test showed that after 25 consecutive dives, regulator and inlet air hose were totally dry.
7) There is no special maintenance required for the mouthpiece and since the regulator will be kept dryer, the maintenance on it will be reduced.
8 ) The mouthpiece has five O-rings:
a) The two on the wagon wheel valves are static O-ring and will probably outlast the silicone mushroom valve.
b) There are two radial O-ring that provide a controlled amount of friction to the DSV rotation (They are not sealing O-rings).
c) There is one O-ring that seals on the mouthpiece opening (or in the closed position). This O-ring can be easily inspected while rotating the DSV and it is easily replaced. The O-ring is captured, it only sees about 10% to 15% compression during operation, and has smooth surface to slide into with a nice rounded edge.
9) Air passage in mouthpiece is very large and optimized to minimize flow resistance.
10) Flow diverter provides smooth flow transition into and out of divers mouth.
The inlet and outlet flow diverter ramp angle are different. They are designed for the difference in the flow velocity (inlet flow with venturi assist versus the slower outlet flow).
11) Flow diverter is optimized to take full advantage of Argonaut Kraken maximum possible venturi flow. See note.
12) Several flow diverter were designed and tested. The attached sketch shows three of the flow diverters tested. They have different height and flow angle. The 2 dimensional drawing is a bit misleading about the true flow path areas, but it should give an idea of the design.


Note: The Argonaut Kraken was specifically design to have a very adjustable cracking effort and venturi flow.

The lowest reasonable cracking effort is limited by the radius of the exhaust valve (about 1/2”). If the cracking effort is adjusted lower than 1/2 inWC, the regulator will tend to have a light free flow when the top edge of the exhaust is higher than the center of the diaphragm.

Without the DSV flow diverter, the amount of venturi flow adjustment in the Argonaut Kraken had to be limited to avoid the excessive flow from blowing past the mouthpiece and out the exhaust. The flow diverter in the mouthpiece was specifically designed to take advantage of the strong venturi flow the Argonaut can be adjusted to. No excessive air is allowed to blow-by past the mouthpiece. All the air is directed towards the diver. Once flow is initiated, only the air used by the diver will be supplied with minimum inhalation effort (with no wasted air out the exhaust).

The sketch below shows three different diverter that were analyzed and 3D model prototypes were tested.

Image


Image


Image


I will be updating this page in the near future.
Luis

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Re: ARGONAUT DSV design information.

Tue Nov 29, 2016 12:20 pm

Luis,

THANK YOU for that very lucid, thorough and easy to follow explanation of the DSV. As a brand-new Argonaut owner (my SE is shipping today), this was very helpful, and as comprehensive an explanation of how to get the most out of the DSV as I could ever hope for.

Bryan told me that all current Argonauts are shipping with the venturi improvements that you discussed in another thread. Maybe you could post an explanation of how to adjust the cracking pressure of the reg?

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Re: ARGONAUT DSV design information.

Tue Nov 29, 2016 10:14 pm

Thanks for the comments.

The regulator you are going to be receiving from Bryan should be adjusted with a cracking effort low enough (just below 1 inWC, but not less than 0.7 inWC). You should not need to adjusted.

There are several adjustments on the Kraken that can affect the cracking effort, but it is best to understand them well before anyone starts messing with them. There are a few ways of adjusting the second stage spring pressure and intermediate pressure is also easily adjusted. All of it affects the cracking effort.

It is very interesting that you are also asking (on a separate thread) about a free flow on a regulator (double hose or single hose). The subject of cracking effort and free flow are totally tied together.

The cracking effort on any regulator (single or double hose) cannot be adjusted less than the distance from the center of the diaphragm to the top edge of the exhaust (in any dive position) or the regulator will free flow when the diver is upside-down or other position that puts the exhaust higher in the water column. I can explain this further when I have more time if it is not immediately clear.

Another point of interest is that cracking effort adjustments are accomplished in tenths of inches of water column (1/10 or 0.1inWC). On the other hand, a poorly located regulator, could place the regulator easily 1 or 2 inches (or more) vertically higher that the diver, in the water column. That directly translates to an direct increase in cracking effort of 1 or 2 inWC (or more). Therefore it should be obvious that focusing on regulator position is more important and will pay off with a potential of 10 times the benefit as opposed to focusing on very minor cracking effort adjustments.

I hope my explanation is clear. I will be glad to expand on this subject on its own thread, but sometimes I am not quick responding.

Thanks
Luis

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Re: ARGONAUT DSV design information.

Tue Nov 29, 2016 10:18 pm

The DSV and flow diverter details.

Here are some pictures of the new DSV with the flow diverter. The white flow diverter was just a prototype, but I it is dimensionally OK so I thought it would help to show it in pictures.

Image


Notice in this picture that the flow opening in the inside tube is much larger than the mouthpiece opening. I did a very careful section by section analysis and model to make sure there was no flow restriction and that the transition flow direction change is actually more gentle than without the diverter.

Image

Image


The “V” looking mark is actually an arrow head to indicate the flow direction. This is the exhaust side. You only need to know this if you take it apart. Everything else is symmetrical, but the diverter has an inlet side and an exhaust side.

Image


This picture shows a Viton (brown) O-ring with a partially closed DSV. This is only a transition view. The DSV should be fully open or fully closed during operation.

Image


In this picture you can see the black flow diverter in place, but I had to illuminate it in order to see it. When installed with the mouthpiece valves and hoses, it would be too dark to see it without shining a light into the mouthpiece.

Image

You may notice that the mouthpiece opening is one of the largest in the industry. Of the typical standard regulator mouthpiece, it uses the larger one typically available. This was again optimized to reduced flow resistance.
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Re: ARGONAUT DSV design information.

Tue Nov 29, 2016 10:21 pm

The primary change to improve the performance is actually very easy and simple. If everything is tuned properly, the only change is to block both of the side ports. That alone will induced a very good and very repeatable venturi flow during inhalation.

The venturi flow in combination with a low cracking suction will sustain the air flow while there is any demand. The diverter will not allow any air flow to be waster out the exhaust. But I have observed that the inhalation effort is nonexistent once flow is initiated.

For those who want the ultimate in performance, there are a few checks that the owner may want to make, to optimize the regulator. Some things are easy to check and adjust, like lever height and IP. The cracking effort is not hard to measure if you have the right set-up.
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Re: ARGONAUT DSV design information.

Tue Nov 29, 2016 10:22 pm

Here I am showing one side blocked

Image


Other side:

Image


Both:

Image


Image


Image



This gives you an indication of the lever height, but I will expand on this more later. You should not need to do anything with the lever height. It should be fine, but I will explain how to check it later. I am just using the scale as a straight edge.

Image


I am pressing a bit with my Mistral tool. Again, more later.

Image


The nozzle points down the full diameter horn. The nozzle flow forms a cone. That is why I designed the can with a full circular tube horn.

Image


The vintage metal cans are attractive and they work well, but the rectangular horn base is not ideal to develop maximum venturi flow. They are good enough for most flow rates, but the Argonaut can was optimized for all flow rates and the DSV flow diverter is essential to take advantage of the maximum venturi flow.

Image


This can was optimized for production (with the soldered or brazed horns) not for flow performance. The rectangular horn base is the same as in the early Broxton regulators with no induced venturi flow at all.

A full sized circular tube horn would have been much more difficult to attach with a clean transition on this can.

Image


I will be adding more later and I will probably separate this post into a new thread talking about optimizing the overall Argonaut performance, but I needed to provide some advance information.

I hope this helps.
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Re: ARGONAUT DSV design information.

Wed Nov 30, 2016 4:57 pm

Very interesting background on the DSV design... thanks Luis!

Yesterday I took delivery of my brand new Kraken... very exciting to actually hold my first double hose regulator :)

I assembled the HOG mouthpiece onto the DSV and had a quick test-breathe with the DSV rotated open (but without the hoses attached to the Kraken body) with inlet and exhaust valves working smoothly...

Then rotated the DSV closed and tried to breathe in, thinking that with the DSV shut I could test for leakage around the newly attached mouthpiece. To my surprise, air was moving in and out of a small hole just below the mouthpiece stub.

This hole looks like it is for another rotation stop screw (like at the front) but is larger in diameter.

If the regulator is pressurised, and the DSV closed then surely I could draw in some water through this hole if I attempt to breathe at the surface? Maybe I am missing something obvious here...

Just wondering what purpose it serves?

Image

Image
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Re: ARGONAUT DSV design information.

Wed Nov 30, 2016 8:22 pm

The hole has two purposes. The primary is described in the quote below.

When you put any regulator in your mouth (single or double hose) you always purge before inhaling (always blow first). With the DSV close it will be obvious that DSV is closed because of the flow resistance. The when you open it everything is totally dry. This will become second nature in very short order.

The arrows in your sketch should be reversed to represent the actual operation.
:)
luis wrote: 4) Water in the mouthpiece byte tube can be purged before opening mouthpiece. This keeps the loop completely dry.
The second (important) reason for the hole is that when the DSV is in the open position, the three O-rings would create a closed void if there is no venting hole. The void between the inner and outer cylinder will not be pressure compensated with the ambient pressure. This could cause a number of potential problems that I didn't want to risk.





On a related subject to divers new to double hose regulators. Some divers have been tough to take very short little breaths. The idea was to keep the buoyancy change while breathing to a minimum. That is not a good idea for several reasons including air consumption because the CO2 is not flushed as well and the over all breathing rate is increased (there are several articles written on the subject and I will add a link later).

With the Kraken (or any regulator that relies on good venturi flow) it is particularly important to take normal full breaths (I repeat "normal") to take full advantage of the venturi flow once the flow has been initiated. Most divers will know what I am talking about when I say normal breaths, but some new divers are been tough to sip their air.

Good full (slow) breaths will also improve CO2 flushing and with time will reduce your air consumption.

I will try to add some links to some studies soon. I have to locate them again.
Luis

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Re: ARGONAUT DSV design information.

Wed Nov 30, 2016 9:05 pm

Hi Luis

Many thanks for your detailed reply... and patience with a DH newbie :oops:

Makes sense now... be interested in reading those links in due course.
'A man can never have too much red wine, too many books or too much ammunition' Rudyard Kipling

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Re: ARGONAUT DSV design information.

Thu Dec 01, 2016 8:36 am

Here is article that I like because it makes a lot sense.

How to Breathe Underwater by Daniel Spitzer, M.D.
Or really, how to master the “dive deeper, breathe slower” approach

http://www.undercurrent.org/blog/2015/0 ... nderwater/



I have other articles that are also related to re-breathers and the studies associated with the "work of breathing" on re-breathers. I mention this because some of the studies related to WOB on re-breathers is fairly relevant to the breathing performance on a DH regulator. A re-breather doesn't have any venturi assistance or any other pneumatic assistance but the position of the counter-lungs and its effects is similar to the positioning of the DH demand valve.


I am mentioning this in the DSV thread, because from my point of view, one of the primary purposes of introducing the DSV was to create a complete breathing system that would reduce the WOB while keeping all the other advantages of a traditional DH regulator. In this case the DSV actually adds to the functionality of the DH regulator in many ways, as described above.

I will add that an extremely important part of the DH breathing system is the back-plate/ harness/ BC system that is used with the with the Argonaut Kraken (or any double hose for matter). It all has to play together well in order to get the best performance.
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Re: ARGONAUT DSV design information.

Thu Dec 01, 2016 4:55 pm

Beyond impressive! Nice job Luis.

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