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Overbalanced first stage with atomic ss1?
- Thread starter Drea13
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eelnoraa
Contributor
Those who do these kind of dives, usually just don't have octo/inflator combo.
By streamline, it really mean one less hose. But this hose will be longer than a usual inflator hose for diver to breath on it. But it also mean it will dangle. I am sure it is actually more streamline.
By streamline, it really mean one less hose. But this hose will be longer than a usual inflator hose for diver to breath on it. But it also mean it will dangle. I am sure it is actually more streamline.
If anyone comes across this in the future with the same question, I used my zeagle BCD with the atomic SS1 and aqualung legend. Deepest dive was 90’, tested the ss1 and had no problems breathing, I also had no free flow issues. Take from that what you will.
As with much of life, you can come here seeking 100% yes/no clarity, but life just doesn't really work that way.
An unbalanced 2nd stage used with an over balanced 1st stage is not guaranteed to free flow, nor is it guaranteed to free flow in certain conditions. But it is more likely for a free flow to happen in certain expected situations, even if the FF is just a slight bubbly leak. Someone else's trouble free past experience does not change that elevated possibility/probability of the potential issue. I steer my customers away from over balanced/unbalanced pairings.
And whether over balancing is by design or by accident does not change the reality that it exists.
In my personal opinion, I suppose it is possible (but unlikely) that once upon a time it was an accidental by-product of a specific design, but I am confident that today it is an intentional choice made by the design engineers.
The over balancing is caused when the area of the pressure transmitting piston in the dry chamber is greater than the area it is acting upon. I am not sure if that is determined by the area of the spring pad, or by the "free" area of the main diaphragm - I think it is the diaphragm. That ratio of difference determines the amount of over balancing. The first Legend has a ratio of 1.36 between the two surface areas, don't know if current versions have changed slightly or not.
Fill the dry chamber with oil instead of a plastic piston to transmit the ambient pressure, and no more over balancing. (No, do NOT just randomly start filling any and every dry chamber with oil...)
An unbalanced 2nd stage used with an over balanced 1st stage is not guaranteed to free flow, nor is it guaranteed to free flow in certain conditions. But it is more likely for a free flow to happen in certain expected situations, even if the FF is just a slight bubbly leak. Someone else's trouble free past experience does not change that elevated possibility/probability of the potential issue. I steer my customers away from over balanced/unbalanced pairings.
And whether over balancing is by design or by accident does not change the reality that it exists.
In my personal opinion, I suppose it is possible (but unlikely) that once upon a time it was an accidental by-product of a specific design, but I am confident that today it is an intentional choice made by the design engineers.
The over balancing is caused when the area of the pressure transmitting piston in the dry chamber is greater than the area it is acting upon. I am not sure if that is determined by the area of the spring pad, or by the "free" area of the main diaphragm - I think it is the diaphragm. That ratio of difference determines the amount of over balancing. The first Legend has a ratio of 1.36 between the two surface areas, don't know if current versions have changed slightly or not.
Fill the dry chamber with oil instead of a plastic piston to transmit the ambient pressure, and no more over balancing. (No, do NOT just randomly start filling any and every dry chamber with oil...)
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