Hard Breathing

[halocline]

All single hose regulators get harder to inhale when you are vertical facing up because of the elevation difference from the regulator diaphragm to your lungs. It doesn’t mater if the regulator diaphragm is facing up (like in most conventional regulators), facing to the side (like in a Poseidon), or facing down (like in an old Scubapro Pilot).

Luis, I'm not trying to take issue with your theory, you obviously understand it better than me, but this last statement is just not true. It does matter, at least with both my regs (SP G250 and R190) which direction the diaphragm is facing; in fact that's exactly what changes the way the reg breathes.

Again, picture a diver vertical heads up, then vertical feet up. In those cases the reg is in a totally different position with respect to the diver's lungs. With my reg there is essentially no difference how the reg breathes in those positions. But, if in any position, I turn so that the diaphragm is facing the surface of the water, the reg gets much harder to breathe. Similarly, a reg will freeflow when inverted mouthpiece up, and stop with mouthpiece down. Mouthpiece up is closest to normal diving position, mouthpiece down is the orientation of the reg when looking directly at the surface. Obviously the reg itself is responding to this change in orientation due to the freeflow. I'm convinced that this is the same effect that causes the reg to breathe harder when looking up than in a normal diving position, and I don't think it has anything to do with our lungs. If it doesn't have anything to do with pressure differential on the diaphragm, it must have something to do with the relative position of the diaphragm and exhaust valve.

BTW, I believe with poseidon regs it's the exhaust valve that's on the side, not the diaphragm. Correct me if I'm wrong.

Don't mean to be argumentative here, just trying to reconcile your theory with my experience.

 

[Greg Barlow]

Similarly, a reg will freeflow when inverted mouthpiece up, and stop with mouthpiece down. Mouthpiece up is closest to normal diving position, mouthpiece down is the orientation of the reg when looking directly at the surface. Obviously the reg itself is responding to this change in orientation due to the freeflow. I'm convinced that this is the same effect that causes the reg to breathe harder when looking up than in a normal diving position, and I don't think it has anything to do with our lungs. If it doesn't have anything to do with pressure differential on the diaphragm, it must have something to do with the relative position of the diaphragm and exhaust valve.

Mattboy,

This is more of a "case fault geometry" reason. Think for a few moments about Luis's example of underwater habitats. When we dive with double hose regs, the water pressure differential really shows its ugly side.

Greg

 

[Greg Barlow]

Another thought for those who question the validity of case fault geometry and water pressure. Why do you think that the original ScubaPro Pilot second stage had such an amazingly low inhalation cracking effort without free-flowing issues? Think about the location of the exhaust diaphragm in relation to the ambient pressure sensing diaphragm. Try and visualize the position of the second stage in relation to a normal swimming position.

Greg

 

[Luis H]

Luis, I'm not trying to take issue with your theory, you obviously understand it better than me, but this last statement is just not true. It does matter, at least with both my regs (SP G250 and R190) which direction the diaphragm is facing; in fact that's exactly what changes the way the reg breathes.

Again, picture a diver vertical heads up, then vertical feet up. In those cases the reg is in a totally different position with respect to the diver's lungs. With my reg there is essentially no difference how the reg breathes in those positions. But, if in any position, I turn so that the diaphragm is facing the surface of the water, the reg gets much harder to breathe. Similarly, a reg will freeflow when inverted mouthpiece up, and stop with mouthpiece down. Mouthpiece up is closest to normal diving position, mouthpiece down is the orientation of the reg when looking directly at the surface. Obviously the reg itself is responding to this change in orientation due to the freeflow. I'm convinced that this is the same effect that causes the reg to breathe harder when looking up than in a normal diving position, and I don't think it has anything to do with our lungs. If it doesn't have anything to do with pressure differential on the diaphragm, it must have something to do with the relative position of the diaphragm and exhaust valve.

BTW, I believe with poseidon regs it's the exhaust valve that's on the side, not the diaphragm. Correct me if I'm wrong.

Don't mean to be argumentative here, just trying to reconcile your theory with my experience.

I am sorry I would need some visual aids to explain it further.

The laws of physics as we (I am using the term “we” to refer to the human collective) know them at this point in time are not “my theory”. Like pescador775 mentioned: as humans expand our knowledge of science, we have often had to revise previous concepts. Just trust me on this one: we are not rewriting any laws of physic here tonight.
I apologize if the above statement sounds arrogant (that is not my intention), but the basic laws of physic are not really up for debate.


The Poseidon Cyklon 300 and Cyklon 5000 have their diaphragm directly on the side.

Just keep in mind when you are in a vertical position and look up you just moved the regulator several inches above the lungs. Moving the regulator a few inches of water above your lungs is a few inches of water pressure that your lungs have to suck. That same sensation happens when you use a Poseidon Cyklon 300. In the case of the Cyklon the diaphragm is always pointing to the side.

Also keep in mind, as I mentioned above, we “humans” are not a calibrated instrument. This is often hard to believe, but many sensations are misleading. This will not totally explain your experience, but keep it in mind.




One of the sad things is that this physics used to be taught in our basic Scuba course.

I remember in my basic Scuba course (in 1971, I was 14) on the second lesson covering what we used to call “the Scuba diving scientists alphabet”:
A, B, C, D, H

For extra points does anyone care to guess the names of the five scientists whose names start with the five letters above? All five scientists introduced basic concepts that affect diving.

 

[Greg Barlow]

I remember in my basic Scuba course (in 1971, I was 14) on the second lesson covering what we used to call “the Scuba diving scientists alphabet”:
A, B, C, D, H

For extra points does anyone care to guess the names of the five scientists whose names start with the five letters above? All five scientists introduced basic concepts that affect diving.

[/QUOTE]

I believe those scientists would be Archimedes, Boyle, Charles, Dalton, and Henry. I, too, got certified back in the 70's. We had a good number of students fail to return to the second class. They couldn't pass the swimming tests....My, how "standards" have changed.

A few years back I was one of the first to take the PADI Nitrox class when it was released to the public. I found an error on one of the questions pertaining to partial pressure of oxygen. When I tried to explain to the instructor why the answer sheet was incorrect, he didn't have a clue as to what I was explaining. Had he been certified back in the days when an alternate air source was a rarity, he might have agreed with me.

Luis, are you going to Portage?

Greg

 

[Luis H]

I believe those scientists would be Archimedes, Boyle, Charles, Dalton, and Henry. I, too, got certified back in the 70's. We had a good number of students fail to return to the second class. They couldn't pass the swimming tests....My, how "standards" have changed.


Luis, are you going to Portage?

Greg

Hi Greg

I figured you were certified back in the 70’s. And yes, your answer is correct.



I am very disappointed that I won’t be able to go to Portage Quarry. I would have like to meet you, and I was looking forward to meeting some of the “legends” of diving: Dr. Sam Miler, Sam Lecocq, etc. I have had some correspondence with Sam Miller and he is a character. I guess when you have been around the sport for so long you are bound to be.

I was able to go to Wazee last year and Sand Dog III this past spring and did a lot of great diving with Rob, Bryan, Dan, Ryan, Nemrod, Karl, Dave Hass and others. It is a great group of divers from all over the country and I was looking forward to meeting more, but at this point its not meat to be; hopefully the next gathering.