Regulator breathes much harder when inverted

[HowardE]

My comment was a cross between a statement and a question. I use poseidon regs for some stuff I do. It seems as though the servo type 2nd stage regulators do well in odd positions.

 

[Akimbo]

My comment was a cross between a statement and a question. I use poseidon regs for some stuff I do. It seems as though the servo type 2nd stage regulators do well in odd positions.

I use an early production Oceanic Omega that is pushing 30 years old. It is also a side exhaust pilot. My fist side exhaust was a Poseidon Cyklon with metal housing, circa 1972. It is a shame side exhausts have not done well in the market. The Omega is a bit "hair trigger" for an octo though. The case geometry and radial exhaust has more to do with positional performance than the servo, but is sure makes for a tiny diaphragm and regulator body.

 

[halocline]

The case geometry and radial exhaust has more to do with positional performance than the servo, but is sure makes for a tiny diaphragm and regulator body.

What do you mean by "radial exhaust"?

SP uses a coaxial exhaust valve on the D series; meaning the exhaust valve is centered on the diaphragm. The pilot and air 1 go one step further and eliminate the exhaust valve altogether, instead mounting the diaphragm with clips so that it can allow air to escape out along it's perimeter, so the diaphragm also functions as the exhaust valve.

Are you talking about something like that, or just the fact that the exhaust valve is round, and attached in it's center, allowing air to escape along it's radius?

 

[halocline]

I going to have to partially disagree, the "pressure" distribution within a small enclosed structure (organ) like the lungs is readily understood and consistent.

N

To my limited knowledge, lungs are more like sponges soaked in blood than they are like balloons. Just out of curiosity, what is the enclosure that you're referring to? Ribcage?

Obviously we have use a large muscle to expand the area that our lungs occupy, allowing them to expand, and we're pushing against a pressure differential to do that. But how the pressure flows and equalizes within the thousands of tiny sacs that make up our lungs is, I suspect, pretty complex.

The most obvious argument against the 'lung depth=breathing resistance" theory is the simple fact that vertical head up means the lungs are at their maximum depth in relation to the reg, and vertical head down means the lungs are at the minimum depth in relation to the reg. Yet, breathing resistance is more or less the same. Lets hear an explanation for that.

 

[Thalassamania]

The OCEANIC OMEGA (and OMEGA II) are also my all time favorite second stages with the Cyclon 300 running a close second. They do breathe a little "wet" but I've never found that to be a problem.

 

[DA Aquamaster]

This is pretty predicatable...this question always goes down this road.

I'm jus' gonna sit in the back and watch...

 

[Akimbo]

To my limited knowledge, lungs are more like sponges soaked in blood than they are like balloons. Just out of curiosity, what is the enclosure that you're referring to? Ribcage?

Obviously we have use a large muscle to expand the area that our lungs occupy, allowing them to expand, and we're pushing against a pressure differential to do that. But how the pressure flows and equalizes within the thousands of tiny sacs that make up our lungs is, I suspect, pretty complex.

The most obvious argument against the 'lung depth=breathing resistance" theory is the simple fact that vertical head up means the lungs are at their maximum depth in relation to the reg, and vertical head down means the lungs are at the minimum depth in relation to the reg. Yet, breathing resistance is more or less the same. Lets hear an explanation for that.

Breathing resistance is one of many characteristics used in regulator design and is often confused with respiratory workload related characteristics. That is the source of endless confusion.

To make matters worse, breathing resistance is a vague term that means different things to hyperbaric physiologists and regulator engineers. Regulator engineers, and Ansti breathing simulators, deal with differential pressure and flow rates at the regulator mouthpiece. The physiologist is looking at the entire breathing workload imposed on a diver, including any effect imposed by regulators. The OP's question crosses the line between the two and context is often intertwined.

This is more a message to all:
Try this experiment: You have to be relaxed and not distracted. It works best if you are not in a wetsuit or wearing a tank so just let it float nearby. Stand waist deep in a swimming pool and breath from your regulator trying to concentrate on your respiratory workload, resistance, or whatever you want to call it. It will be slightly more effort to breath form the regulator in air than without, but not much. Now sit or squat until you are completely submerged, but still vertical from the waist up. Almost everyone can easily detect that additional effort is required to breathe. Now go horizontal until the regulator and the center of your chest are at the same depth. Most people will also notice that difference. Now go to the face/regulator up position and note the change.

Now go back to the horizontal as close as you can estimate and relax again. Now move your head up about 4" and see if you can honestly detect any difference. I have never seen anyone who can.

What is this example telling us?

• We know there is a difference of in hydrostatic pressure.
• If a simple partially inflate air bladder were connected to the regulator in place of lungs, we know the regulator would vent air from the bladder out through the exhaust valve.
• We know the regulator does not vent when the regulator is higher, or free-flow when it is lower, while it is in our mouth.

So there are additional factors influencing pressure at the regulator mouthpiece, which translate to the major portion of respiratory workload. Human diaphragm and chest muscles make the lungs act more like a piston than an air bladder. We can sense the workload change from the pool experiments described, on top of performance related to regulators.

Humans don’t have nerve endings in our lungs so it is hard to sense exactly where the changes in effort occur. Most people are too distracted to notice at all under normal diving conditions because the difference is slight and distractions are so great.

Basic hydraulic physics do apply, but are not quite as simple as my fist explanation or Nemrod's illustration might imply. However, the differences you detect do follow the analogy very close and explain the vast majority of forces at play.

 

[Akimbo]

What do you mean by "radial exhaust"?

SP uses a coaxial exhaust valve on the D series; meaning the exhaust valve is centered on the diaphragm. The pilot and air 1 go one step further and eliminate the exhaust valve altogether, instead mounting the diaphragm with clips so that it can allow air to escape out along it's perimeter, so the diaphragm also functions as the exhaust valve.

Are you talking about something like that, or just the fact that the exhaust valve is round, and attached in it's center, allowing air to escape along it's radius?

The nomenclature I am familiar with refers to a radial exhaust when the gas exits the regulator housing around the outside of the diaphragm. It could be past the outer edge of a diaphragm with a secondary roll of exhaust mushroom valve, or through a series of radial holes in the housing sealed with a special molded rubber ring.

Concentric designs have a mushroom valve mounted in the center of a concentric diaphragm. Oceanic used a concentric diaphragm with side exhaust on their Omegas.

The regulators with separate diaphragms and exhaust valves that dominate the US market I most often hear called bottom exhausts.

I have been exposed to a number of US, British, and Norwegian regulator projects since the early 1970s so I don’t know if this nomenclature squares with current jargon in the US or not. I didn't give it much thought until you asked.

 

[Akimbo]

… 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 have re-read your message and you are looking only at regulator performance at the exclusion of respiratory workload. The question was not about breathing machine tests but actual perceptions in the water. Dozens of researchers have confirmed that the pressure gradient on a submerged human chest has measurable effects on Tidal and Residual volumes, Inspiratory and Expiratory Reserves, and Vital Reserve. The most readable text I have is Underwater Medicine by Captain/MD Stanley Miles, but there are dozens more.

The Scubapro D400 you cite is nothing more than a bottom exhaust pilot valve with a concentric diaphragm — functionally no different than the side exhaust pilots. The Case Geometry Fault you describe does improve regulator performance but still has a greater respiratory work load than a diver in a rigid hat with a neck dam and enclosed regulator like the Oceaneering Rat Hat, the Sat Hat, or some of Westinghouse's prototype Krasberg hats. Even these hats are not immune from measurable effects on human lung performance degradation due to hydrostatic pressures.

 

[Nemrod]

This is pretty predicatable...this question always goes down this road.

I'm jus' gonna sit in the back and watch...

Guys, y'all gonna have to whip DA up a bit more than this flaccid response to provide us some good entertainment because if you are depending on me you are out of luck as I simply am in no shape or willingness to give fight. I am much to busted and broken and scuffed and rumpled up for the usual game, sorry I am not up to my usual ability to enrage everybody and make you all want to pull your hair out after smacking me smartly with a 2X4 (and I mostly deserve it and finally got it )

Maybe in a few weeks I will be more fit for the fight.

Love, :blinking:
N