Argonaut Mechanism - diagram and parts list

[Luis H]

The video below is a spin-off from one of the many analyses I did during the detail design of the Argonaut.

This animation is a simulation of the mechanical motion of the parts.

NOTE: THIS VIDEO IS NOT A REPRESENTATION OF A BREATHING CYCLE. It shows cycling the demand valve into a fully open position. Fully opening the demand valve will only occur during artificial “worst case” test modes. The flow rate capacity of the fully open demand valve will exceed any diver demand, at any realistic work load, and at any depth where air could be reasonably used (in deeper dives, helium/tri-mix is recommended).

One of the many things that was calculated is the mechanical advantage of the lever during the full motion cycle. The letters and arrows in the video represent key dimensions used in some of the calculations:
• D1 (Delta1) and D2 (Delta2): represent the primary displacements in response to the demand valve diaphragm action.
• L1 and L2: are used to determine the lever mechanical advantage as a function of travel passion.
• S1: the spring compression. It is used to determine spring force (again, for the full range of travel).
• Some of the other variables are used for other calculations.
• The blue arrows represent directional vector forces on the lever (the arrow size does not indicate force magnitude).

The analysis associated with this animation is actually one of the simplest analysis that was performed, but it produced an interesting visual image of the functional parts in action.

Note: In addition, I also did structural analysis on most of the parts. As part of the flow analysis, I have many drawings of section cuts of the complete flow path showing flow cross sections.

The data generated from the calculations has been validated and verified whenever possible with component and/or system testing.


[video]
First stage:
If you are familiar with a Royal Aqua Master (RAM) or a Conshelf first stage, you will recognize similarity with the Argonaut first stage. That (RAM) first stage design has proven to be the most dependable with over 50 years good reliable history behind it.

Air passages:
Downstream, the air passages between the first and second stage of the Argonaut are totally new and much improved from a RAM. The flow pass impedance is lower than other double hose or single hose regulators. Confirmation of the improved inter-stage flow comes from an almost instantaneous Intermediate Pressure (IP) recovery during a breathing cycle (measured on any of the ports).

Second stage:
Unlike the first stage, the Argonaut the second stage is very different from a RAM. It combines the success of my HPR design with a new volcano orifice and a new venturi flow alignment/ interface with the hose-horn in the case. The venturi flow is smoother with the hose-horn designed to match the air flow out of the nozzle.

The demand valve (second stage) is the key component in achieving a great-performing regulator. Therefore, I opted for a simple modern design with good track record of performance and reliability.


Mechanically the second stage has a very simple appearance, but it incorporates several important details to minimize friction and maintain a very predictable motion for very smooth performance:

• The lever-fulcrum and lever-work-point are well defined contact edges with stainless steel washers for a bearing surface with a long predictable/ low friction life.

• The second stage is assembled as a module. The lever contact points in the module are self-aligning, with no binding or unnecessary friction

• All materials were selected for durability and low friction, including the round synthetic beads at the tip of the levers.

All the critical parts (volcano orifices, lever, lever bearing washers, springs, seat carrier, etc.) can be replaced if damaged, worn, or corroded in order to maintain the highest level of performance.


The case/ housing:
Not shown in the video is the housing. The housing was specifically designed to be integrated with the venturi flow design of the second stage. The hose-horn alignment, the shape, and the distance from the jet were design to optimize the venturi flow. The diameter of the horn was driven by the preferred hose size, therefore the other three variables were adjusted for the desired flow pattern.

 

[Luis H]

 

[Luis H]

Argonaut Kraken flow rates
Note: This a bit out of date (as of 2017). With the new DSV mouthpiece, it is possible to adjust the venturi flow to be more aggressive that what is shown in this videos, but this gives an idea of the flow potential.

During the design and development of the Argonaut, I did a lot of flow calculations and testing, but I had the opportunity to do some more flow testing last week, I had several tanks that I needed to empty (for hydro testing) so I had a lot of compress air to use up.

I wanted to get some solid numbers showing how long it took to empty a full steel 72 and a full high pressure steel 80. BTW, this steel 80s actually hold 85 cu ft.

Warning: The two videos below are very boring videos showing the pressure gauge needle moving down while the venturi flow on two different Argonauts is used to bleed the tanks dry. One video is almost 5 minutes long and the other 3.5 minutes. You can fast forward the videos. If you watch the full video, you may regret that you will never get that time back.

My Argonaut regulators are normally tuned hot enough that all I have to do is pull a slight vacuum from the mouthpiece and the venturi flow will continue the flow. I am not doing anything other than initiating an intentional free flow and I am letting it flow.

The bottom line is than an Argonaut can empty a full tank (steel 72 or 85 cuft) in 3.5 to 4.5 minutes. That is a flow rate of 16 to 22 cfm. This type of potential flow rate far exceed the needs of any diving situation. Let me know if you are ever in a diving situation where you need to empty a tank in less than 5 minutes. :shock:

I have seen claims of flow through piston first stages than can flow 300 cfm. In theory that first stage would empty a steel 72 in 14 seconds. Impressive numbers, but it is not realistic or practical value. That was only the first stage and I am guessing that it was tested with a high flow valve and constant air pressure source.

My test was for a complete regulator, including the hose loop, attached to a standard scuba valve and tank. The two regulators did flow air at different rates. I can explain more about the difference later.

The tank pressure is obviously dropping. I have taken readings from the videos and plotted the data of time versus pressure drop. It looks fairly linear.



Argonaut draining St 72 from Luis Heros on Vimeo


Argonaut draining st 80 from Luis Heros on Vimeo

 

[Luis H]

Double hose regulator exhausts flow resistance.
Note: I did this in July 2013 with an early Argonaut prototype 3D printed can. The new can has actually better performance.

I took some comparative data of some of the exhaust valves used in double hose regulators.

To take the data I used a Magnehelic and a Dwyer flow meter.

To supply the air flow I used a blower (from a new shop vac that I bought specifically for this type of test) to generate relatively high flow rates.

Notice that I am using air flow at 1 atmosphere, but I am increasing the air flow to higher that realistic values in order to replicate the Reynolds numbers expected at normal diving depths. I don’t have the facilities to test at hyperbaric pressures to increase the air density, but I can increase the air flow and obtain the same Reynolds numbers.

Everyone can understand comparative testing even if you are not following the significance of non-dimensional Reynolds number scaling.

Let me just say that the test conditions are controlled to create a realistic and comparative conditions.

I adjusted the air flow to accurately reproduce the same conditions during all data collection. Only one variable was changed at a time following well established scientific methods for data collection.

Notice that this data is only for steady-state flow. The breathing cycle is closer to a sine wave / transient type of flow.

I tried to also take initial cracking effort (initial valve opening) data, but the numbers tends to be too low to accurately measure. The only observation I can add is that duckbills do tend to stick at times, but I think we have all observed that.


The Magnehelic that I was using only reads up to 5 inWC, therefore I only took data with a pressure delta below or equal to that level. You will see a couple of data points were I could not reach the 10 cfm level without exceeding the 5 inWC limit.

The pressure differential data is just the raw data as I read it. Some of it was expected, but some was a bit of a surprise.

The data was very easy to take with one exception, the silicone duckbill fluttered a lot with 10 cfm of flow. This caused the needle to move wildly. The reading shown was my best average of the fluctuating gauge.

Here are the test samples.

The Argonaut can is a 3D printed prototype. It is intentionally blurred in the pictures for a couple of reasons… There will be more pictures of the new cans in the near future.

Here is part of the test set –up.

Attached in this picture is the can with no valve used as a baseline for comparison testing.

Here is the Scubapro 109 connected for testing.

I bought this little vacuum cleaner specifically to use id as a blower for this type of testing (either for blowing or to generate suction/ vacuum).

 

[Luis H]

Here is a cross-section with the can. I am showing the inlet and outlet horn at 180 degrees from each other to avoid an odd looking cross-section.

The lines are not sharp, like in the drawing. I have to play with the printing.