How deep have You dived with your Double Hose Regulator?
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In 2022:
This one below is in 2023.
In this case I used my Argonaut Kraken for every gas mix except the EAN99 (100% O2) deco gas. I stayed in the double hose loop during most of the dive and switch gases with a low pressure high flow quick disconnect, to supply my regulator with gas from the different side mount cylinders. I could physically show my buddy when disconnected and then connected to a different gas cylinder.
This one below is in 2023.
In this case I used my Argonaut Kraken for every gas mix except the EAN99 (100% O2) deco gas. I stayed in the double hose loop during most of the dive and switch gases with a low pressure high flow quick disconnect, to supply my regulator with gas from the different side mount cylinders. I could physically show my buddy when disconnected and then connected to a different gas cylinder.
I thought that I had explained everything, but that thread was over 3 years ago. What post number did I say that?
Pneumatic locking the DH (double hose) is a very simple concept.
In principle all I am doing is setting the DH first stage to a relatively low IP, in this case at 120 psi and supplying different gases from higher IP side-mount sources. The DH first stage is locked closed as long as the pressure doesn’t dip below the DH 1st stage set point. I did a lot of testing to verify and monitor this performance.
The Argonaut Kraken second stage has such a good mechanical advantage and such a good performance that the cracking effort and breathing performance is excellent with the low IP (115 psi to 126 psi) supplied by its own fist stage, or by the higher IP supplied by the Conshelf first stages on the side mount cylinders.
I picked Conshelf first-stages because of their reliability and performance. Mechanically, the Argonaut first stage valve uses the same valve components as the Conshelf.
I also hand picked the specific 4 Conshelf first stages for my side mounts for their minimal IP swing and very consistent IP at any tank pressure. This gave me the assurance that the intermediate pressure supplied to my DH would never dip below the DH first stage opening pressure.
The graph below shows the static IP of several regulators that I tested for this project. The graph also shows 2 Aqua Lung Titan (same as Conshelf). This was the initial data, I tweak the IP settings before the dives.
Notice the piston regulator is the unbalanced piston that I used for the 100% O2 deco gas. That is the only first stage design that I would ever consider using for a high O2 application, for a number of reasons. That first stage did not supply the DH.
I also did a lot of dynamic flow testing to make sure the Conshelf supply IP never dipped below the 125 psi level at the highest expected flow rates.
At the end, I did end up adjusting my Argonaut with a slightly lower IP, to provide a good margin.
BTW, after I did all my testing and those deep dives, I happen to be talking to the owner of a rebreather manufacturing company about the use of pneumatic locking to different supply first stages. They have tried it, and they were not successful, because the IP they used was too close to each other. Their second stage performance suffered when they lowered one of the IP below the 120-psi level. Their application was for some bail-out configuration (I don't know the details).
I lowered the IP of my Kraken to close to 120 psi and the Conshelf/ Titan were close to 140 psi. That was enough separation to have a reliable pneumatic lock.
During the dive I monitor my back cylinder pressure, with a precise digital gauge to double check that no gas was being drawn from that cylinder during the travel or deco phases of the dive. The back cylinder contained the gas for the bottom phase of the dive.
Pneumatic locking the DH (double hose) is a very simple concept.
In principle all I am doing is setting the DH first stage to a relatively low IP, in this case at 120 psi and supplying different gases from higher IP side-mount sources. The DH first stage is locked closed as long as the pressure doesn’t dip below the DH 1st stage set point. I did a lot of testing to verify and monitor this performance.
The Argonaut Kraken second stage has such a good mechanical advantage and such a good performance that the cracking effort and breathing performance is excellent with the low IP (115 psi to 126 psi) supplied by its own fist stage, or by the higher IP supplied by the Conshelf first stages on the side mount cylinders.
I picked Conshelf first-stages because of their reliability and performance. Mechanically, the Argonaut first stage valve uses the same valve components as the Conshelf.
I also hand picked the specific 4 Conshelf first stages for my side mounts for their minimal IP swing and very consistent IP at any tank pressure. This gave me the assurance that the intermediate pressure supplied to my DH would never dip below the DH first stage opening pressure.
The graph below shows the static IP of several regulators that I tested for this project. The graph also shows 2 Aqua Lung Titan (same as Conshelf). This was the initial data, I tweak the IP settings before the dives.
Notice the piston regulator is the unbalanced piston that I used for the 100% O2 deco gas. That is the only first stage design that I would ever consider using for a high O2 application, for a number of reasons. That first stage did not supply the DH.
I also did a lot of dynamic flow testing to make sure the Conshelf supply IP never dipped below the 125 psi level at the highest expected flow rates.
At the end, I did end up adjusting my Argonaut with a slightly lower IP, to provide a good margin.
BTW, after I did all my testing and those deep dives, I happen to be talking to the owner of a rebreather manufacturing company about the use of pneumatic locking to different supply first stages. They have tried it, and they were not successful, because the IP they used was too close to each other. Their second stage performance suffered when they lowered one of the IP below the 120-psi level. Their application was for some bail-out configuration (I don't know the details).
I lowered the IP of my Kraken to close to 120 psi and the Conshelf/ Titan were close to 140 psi. That was enough separation to have a reliable pneumatic lock.
During the dive I monitor my back cylinder pressure, with a precise digital gauge to double check that no gas was being drawn from that cylinder during the travel or deco phases of the dive. The back cylinder contained the gas for the bottom phase of the dive.
I am not sure what you mean by “LP bridging”? Is it just connecting different LP sources.
I am also not familiar with the Submatix SCR rebreather.
Pneumatic locking may sound sophisticated, but it is not. In my application, I am just locking closed the first stage (in the DH reg.) by introducing a higher pressure from a separate IP source.
It was a convenient way of shutting off the gas from my back cylinder without having to reach the tank valve, which is low on back.
It is a extremely simple pneumatic control application.
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