What about Poseidon Regulators?
Regulator breathes much harder when inverted
- Thread starter Onewolf
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
No, that does not really explain it, although people often promote that theory, as well as in some cases a location of the middle ear versus the lungs/mouth theory that also does not explain the phenomenon correctly.
It really is mjust simple physics and is readily measurable. It gets argued here periodically and some otherwise very smart people argue some very interesting but incorrect theories. Pictures and diagrams don't make an incorrect theory any more valid - especially when they are an adaptation of diagrams that made sense in reference to a double hose regulator where the location of the can (and by default the second stage diaphragm) made a significant difference that is not present to the same degree in a single hose design.
The irony here is that that diapgram does, in a broader sense, illustrate the concept of case geometry fault, you just have to consider the "case" in a larger sense, or more correctly, put the case in its proper perspective.
I am not in the mood to try to explain it yet one more time, but search for "Case Geometry Fault" and you'll get several past explanations of how it works, the specific impact it has on inhalation effort, and ways to avoid it (the D400 for example).
Try this one for starters:
Case Geometry Fault explained
And as an aside, before the argument gets started, if you change positions with the D400, you do not experience the increase in inhalation effort, whihc effectively disproves the position of lungs versus mouth theory.
I am not sure if you are you are taking issue with Nemrod's illustration also or just my explanation. I believe my first post is consistent with the illustration, though not nearly as succinct. I tried to explain the physics in a little more detail in addition to often confused performance criteria in my second post.
From your comment and link, I believe you are looking at regulator performance in isolation from respiratory work load, which plays an important roll in how regulator performance is perceived by a diver.
R&D work has been done to determine the optimum pressure sensing location on the human body to reduce respiratory work load. Multiple pressure transducers were positioned around the body so a computer could calculate pressure at some internal location in the body and control a solenoid valve in place of a demand regulator. As I recall, the best respiratory work numbers were produced by "sensing" a little above the center mass of the lung, probably closer to the center mass of the entire respiratory system. The information was used to see if a pressure assisted supply system could allow practical work at greater depths on HeO2.
The test was a lab geek's wet dream and totally impractical, but it did clearly demonstrated to me that perceived changes in breathing resistance did not accurately correlate to reduced respiratory work load. There were even experiments to bias inhalation in inhalation differently to compensate for human mechanics.
In any case, I am interested in your comments.
I will not be diving for a while..halocline
Contributor
It's not the lungs. First of all, what is the "depth" of the the lungs? Top of lungs, bottom of lungs, middle? Lungs could have potentially a 12" difference in depth between top and bottom, and 12" difference in depth is FAR more than any regulator is going to function in.
Further, any single hose regulator will breathe with more or less the same resistance if you are vertical heads up and vertical heads down, even though these two positions represent the absolute biggest difference in depth between the regulator 2nd stage and the lungs. (Whatever you decide to call that depth) There is no escaping this fact, yet the "lung depth" crowd seems to ignore it.
However, when you start to change the relationship in depth between the mouthpiece (or any exit point of the air from the reg) and the diaphragm/lever contact point, that's when the difference in breathing becomes evident. This is true with both single hose and double hose regulators. The positions of horizontal/facing the surface and horizontal/facing the bottom represent the most difference between mouthpiece (exit point) and diaphragm depth, and that's why you have the radically different resistance.
The explanation of case fault geometry in the Wolfinger book discusses the difference between diaphragm depth and exhaust valve depth. This is a contributing factor, because the exhaust valve is the upper limit on gas pressure in the 2nd stage body. Although Wolfinger does not (to my memory) include discussion of relative depth of mouthpiece/diaphragm in the case fault geometry chapter, IMO it's useful to consider this as another example of case fault geometry; it is basically the same issue, just with a different exit point.
Further, any single hose regulator will breathe with more or less the same resistance if you are vertical heads up and vertical heads down, even though these two positions represent the absolute biggest difference in depth between the regulator 2nd stage and the lungs. (Whatever you decide to call that depth) There is no escaping this fact, yet the "lung depth" crowd seems to ignore it.
However, when you start to change the relationship in depth between the mouthpiece (or any exit point of the air from the reg) and the diaphragm/lever contact point, that's when the difference in breathing becomes evident. This is true with both single hose and double hose regulators. The positions of horizontal/facing the surface and horizontal/facing the bottom represent the most difference between mouthpiece (exit point) and diaphragm depth, and that's why you have the radically different resistance.
The explanation of case fault geometry in the Wolfinger book discusses the difference between diaphragm depth and exhaust valve depth. This is a contributing factor, because the exhaust valve is the upper limit on gas pressure in the 2nd stage body. Although Wolfinger does not (to my memory) include discussion of relative depth of mouthpiece/diaphragm in the case fault geometry chapter, IMO it's useful to consider this as another example of case fault geometry; it is basically the same issue, just with a different exit point.
I going to have to partially disagree, the "pressure" distribution within a small enclosed structure (organ) like the lungs is readily understood and consistent.
I don't argue against the case geometry fault, obviously that is a large component.
The middle ear thing, not saying that is not a component, I am just not an adherant of that hypothesis.
The diagram I posted is correct (enough) to transmit the concepts at work even if incomplete. If you must, just strip the double hose from the left side and it is no longer "vintage" and of course, yes, it would be nice to have a set of diagrams showing today's regulators and consideration of case geometry included.
Good morning everybody
..N
Until we can plant pressure transducers in multiple locations inside a functioning lung under hydrostatic pressure, we cant say with certainty how much the connective tissue effects pressure differential. We know for sure that the effect is pretty darn small to the point it has no practical effect outside of very high gas densities; and maybe not even then.
Unless there has been newer work I am not aware of, this comment in an earlier post explains:
The term "center mass of the lung" is loosely used to describe this location where average occurs, which is the point in Nemrod's illustration. We also know with certainty and practical experience that the closer the center of the regulator's diaphragm and the "center mass of the lung" are to the same depth, the respiratory work load and the perceived breathing resistance are the minimum for any give regulator on the inhalation side of the cycle at least.
It is all a game of choosing diver positions that you spend the most time in. Side exhaust regulators perform best when the regulator body is horizontal, which is the majority of the time. All of the modern side exhaust regulators I recall use coaxial exhaust valves which reduces the distance between the high point on the exhaust and diaphragm center to the minimum practical and makes it more consistent in most positions. Basically, they use a flexing rubber ring around the diaphragm instead of a single mushroom valve.
This improves regulator performance over more common designs in the greatest variety of common diver positions. You can achieve optimum hydrostatic balance on a "standard" regulator in one position only, when the diaphragm center and exhaust are level. Depending on the exhaust flow rate, it is somewhere between the center and shallowest point of the exhaust mushroom valve.
Unfortunately, side exhaust regulators are out of favor because divers are not conditioned to roll the exhaust valve down to dump small amounts of water that naturally leak in past your lips the big complaint being they "breathe wet". In reality, all regulators "breathe wet" when the exhaust is higher than the bottom of the regulator housing, like upside-down. I see ambidexterity as the greatest advantage for shared breathing and equipment flexibility.
Is all this a good reason to switch to side exhaust, probably not. Very few divers can tell the difference or have a critical need for ambidexterity. I personally like and use one most of the time, but the difference is not huge.
Similar threads
