Reg seems to breathe harder when looking up?

[H2Andy]

Uncle Ho, take a ruler and measure from center of your chest to your mouth. What is the distance? ... Get it?.

"Get it?" ya funny

point is, i can't FEEL the difference, my good man. that is, indeed, the issue
(i'll go real slow):

whether there is a noticeable difference in breathing difficulty between a horizontal and a vertical breathing position.

my own experience tells me that there is no noticeable difference

 

[John C. Ratliff]

H2Andy,

I will bet that, when you think you are swimming supine (face up) that you are actually somewhat off the horizontal plane. You will probably not be horizontal, but have your head quite a bit higher than your lungs. Remember, you have to take the mid-point on your lungs in a three-dimentional model. Similarly, when you swim prone (face down), you probably are not swimming completely horizontal, as that would put your regulator below your lungs (most of us have a jaw which is in front of our chest in a natural position), or right at the center of the lungs (look at my avator to see this position). A good way to check if you are completely horizontal in a supine position is to have a bit of water in your mask, and if you are horizontal, it will enter your nose (just kidding, while this is true, don't try it as it is very uncomfortable). But if you watch your buddy doing these manouvers, you will see where his lung position is (center of the lungs--see the diagram on the vintage website), and where has regulator is, then look at the number of inches vertically between the two. If you are completely horizontal, that difference is still significant as your regulator is not in the center of your head, but in front of your mouth (unless you use a two-hose regulator).

By the way, this is independent of how far you are from the surface, as our lungs are not sensing surface pressure. What can affect regulator performance at depth, so that it "feels" like it breaths easier, is that the venturi effect may be more pronounced at depth than closer to the surface due to the more dense air or gas. But a 6 inch (or more) water pressure difference is noticable at about any depth for breaking pressure. If the venturi is really good, you need no further effort at depth until you stop inhalation, and the pressure backs up to the regulator, stopping the flow. It is the breaking pressure that we are talking about.

One other possibility is that, in looking up high, the trachia is extended to the point where it starts collapsing due to the pressure difference, and that by turning slightly, the trachia (wind pipe) is opened, allowing the breathing to take place (theory).

To illustrate this, look at the below photo of me in Clear Lake, Oregon:

In this position, note that my regulator is right at the center of my lungs in a horizontal plane.

In this earlier photo, while my body is horizontal, my regulator is higher, situated on my scuba tank:

This makes inhalation easier, but exhalation easier. The regulator won't bubble because the exhaust is right at the second stage diaphragm, which is what Cousteau patented with his Aqualung patent, and described well within the patent.

Now, look at this photo of me. Here I'm not horizontal, but close:

My double hose regulator is quite high off my lungs, so breathing was fairly difficult in this position. If I had been using a single hose regulator, my mouthpiece is at right about the center of my lungs, and it would breath quite nicely. Now, envision this position, but turned upside down. You'll see that my mouthpiece would be quite a bit higher than the center of my lungs, as it sticks out from my chin. I think this is why you are feeling more difficulty breathing in the supine position as opposed to the prone position.

SeaRat

SeaRat

 

[pescador775]

One supplemental fact, although inhalation is harder in the vertical; by the same token, exhalation is proportionately easier.

My point about pressure differentials is not related to "surface" effects but rather to proportions. I have no idea if this is demonstrable but a pressure gradient of 1% (shallow) should require a greater effort to overcome than a gradient of 0.4%(deep). As I said, I don't recall noticing this with a double hose and I don't think it happens, but I may have experienced with a single hose. Just can't remember a specific situation. Well, any way it is viewed, the size of the water columm is the same, several inches........so, maybe I'm overthinking the problem. Yeah, although at depth the ramp (slope) is shallower (in percent) the total height is the same. So, the effort should be the same.

 

[Luis H]

I have always wondered how much of the perceived breathing resistance is actual versus a perception due to our limited sensory system. Just a classical example: you have a block of wood and a block of aluminum in a room for several days. When you touch them the aluminum feels colder than the wood. They are both at the exact same temperature, but humans don’t measure temperature. We actually measure how heat flows in or out of our skin, but we think we are measuring temperature. We are also not very good at measuring weight, pressure, or even distance.

The cracking breathing resistance of a regulator is measured in inches of Water Column (inWC). The difference between a good regulator and a mediocre one can be less that 1 inWC. The Magnehelic instrument I use to check my regulators (both double hose and single hose regulator) only goes up to 3 inWC. The actual cracking effort of most of my regulator ranges from 0.3 inWC (for my best Royal Aqua Master) to around 1.5 in WC.

In a vertical position when I tilt my head from looking forward to looking up the center of my Scubapro diaphragm moves up about 4 inches. You can check this by standing in front of a mirror with a ruler and the regulator on your mouth. With the Poseidon Cyklon the height change is a tiny bit less because the diaphragm is a bit closer to the pivot point of my neck. In the water that 4 inches will be 4 inches of Water Column of extra inhaling resistance. There is no way around that.

When it comes to no noticeable breathing resistance between your body being vertical or horizontal, the only explanation I can come up with is that maybe the sensors for breathing resistance are closer to the neck than the lungs. The effort is taken place at the lungs but the sensation may come from closer to your mouth. I honestly don’t have the medical background to explain it.

I do know that sensations do vary from person to person. I notice a difference when I am vertically head up or head down with a single hose regulator. Perhaps I have become very sensitive to position since I dive a lot with a double hose regulator.

 

[halocline]

Please explain why regulators will often free flow when in the water mouthpiece up, and will stop when turned mouthpiece down. Then, please explain why this characteristic would not have an effect how the regulator feels when inhaling.

 

[Luis H]

Please explain why regulators will often free flow when in the water mouthpiece up, and will stop when turned mouthpiece down. Then, please explain why this characteristic would not have an effect how the regulator feels when inhaling.

That one is easy. Pure physic (no human physiology). I just hope my explanation is clear.

In the case of my balanced Scubapro the mouthpiece opening is 2.25 inches higher than the diaphragm (when the mouthpiece is up). That regulator will start flowing air if the differential pressure is about 1 inWC or higher. Once the flow is started the venturi will just assist it.

When you turn it with the mouthpiece down the air pressure inside is the same as the opening at the bottom.

Remember the outside water pressure changes with depth, but the air inside is at a constant pressure (like in a diving bell or underwater habitat).

You can normally stop the free flow by just turning it sideways (unless the venturi is going full bore). If you dip the regulator in a horizontal position it should not free flow. You can try it in the bathroom sink.

Again the effects are the same with a Poseidon with the diaphragm facing left, but still the center is about 1.5 inches lower that the mouthpiece opening.

 

[John C. Ratliff]

Mattboy,

The regulator will not free flow in any position if it is filled with water. Dacor, with their PACER line of regulators, made a regulator that would automatically stop free flowing and allow the reg to fill with water. Whenever you have an air pressure differential between the center of the diaphragm and the mouthpiece of greater than the cracking effort of the regulator, you will initiate a free flow. Placing a finger into the mouthpiece, which allows water into the regulator, will stop the free flow. If you measure the distance between the end of the mouthpiece, and the center of the diaphragm, it sometimes is up to two inches, which translates to a water pressure differential of two inches.

But the position of the mouthpiece to the diaphargm does not automatically mean that, upside down, the breathing effort for exhalation will be greater. It is not the mouthpiece that makes the difference as it is a closed system while in your mouth--it is the first opening that makes a difference. That opening is the exhaust valve, as I have explained above.

You are right, there will be a slight variation in the pressures for exhalation. But the inhalation will remain the same at the same height over the center of the lungs, no matter the orientation of the regulator in the water column.

One thing I see in this thread is the inability of some people to differentiate between the inhalation resistance ond the exhalation resistance. But this is an important distinction, as the two are very different. It becomes more apparent with a double hose regulator, as this type of regulator is normally not in the same plane horizontally as the diver's mouth. For single hose regulators, the difference between center of the diaphragm and the exhalation valve (1 inch to 2 inches) in the orientation of the regulator is relatively insignificant as compared to the difference between the center of the diaphragm and the center of the lungs (0 inches to + or - 8 inches of water pressure). If you do the math, the regulator orientation between the diaphragm and the exhaust valve is between 0 to 1.5 inches of water pressure, or 0 and 0.05 psi. The difference between a head down position and a head up position can from zero inches to up to 16 inches, or 0 psi to 0.667 psi, a relatively huge difference.

(To get those numbers, remember that one atmosphere is 14.7 psi, and is represented by 33 feet of salt water. 14.7 psi divided by 33 feet = 0.445 psi per foot; divide this by 12 inches per foot, and you get 0.037 psi per inch of salt water.)

Since you do aquarium design work, it's like the joints of your aquarium. At one inch below the surface, the joint does not need to be too robust. But at 12 inches (0.445 psi) the joint has to be good, or you will get a leak. If you have a large aquarium, say 18 inches high, the bottom joint has to work.

Now, imagine trying to breath water at 18 inches water pressure differential. It is nearly impossible, as this is measured in pounds per square inch of body surface. There is a lot of surface area on the chest wall and diaphragm of our body. It can amount to a ton of combined pressure. Say our body's chest is a cylinder that is 8 inches high, and 14 inches in diameter, or 7 inches in radius. The formula for the area of a cylinder is two times pi times the radius squared times the height. If you do this multiplication, you get a surface area of 3,217 inches squared, or approximately 3200 square inches. Multiply that times the 8 inches of water pressure between the mouth and the center of the lungs, and you get 0.037 x 8 = 0.297 psi, or 0.3 pounds/square inch x 3200 square inches = 950 pounds on the chest wall (this is simplified, but approximately what is experienced).

If you go up to 8 inches, this is the difference in pressure when a diver looks up with a single hose regulator in his/her mouth. It becomes very hard to breath in, but very easy to breath out (950 pounds of water pressure pushing against the chest to push air out). But if he moves the orientation of the regulator so that the exhaust valve is in line with the diaphragm, it is even slightly easier to breath out, but in relation to the huge pressure on the chest, insignificant (although some can feel it).

SeaRat

 

[pescador775]

Luis has mentioned this before but it bears repeating. When a regulator is inverted (mouthpiece down) in the water, there are several forces possibly acting on the diaphragm. Any air bubble inside the regulator can exert upward pressure on the diaphragm with predictable effect. Air pressing against the rubber membrane allows the demand valve to move into a closed position. This is due to the buoyancy of the bubble. Buoyancy occurs in accordance with Archimedes' principle of displacement. However, when the same regulator is placed in the diver's mouth and inverted, the air bubble inside the regulator body is not buoyant, can not exert buoyant forces on the diaphragm as it is inside a closed space and no longer displaces any water. However, one force, the water columm formed by the height of the diaphragm to mouthpiece, exerts an effect either way, in the mouth or not. That is the pressure differential between the diaphragm and the mouthpiece, and as it relates to the lungs, this time acting to suppress flow, as discussed above

 

[slackercruster]

for many regs, it is

on the other hand, there are many regs that breathe very well in almost any position
(upside down, sideways, head up, head down, etc.)

it doesn't mean your reg is unsafe, but it does mean that you should be careful, especially at depth

without any other sign of trouble (difficulty breathing in normal attitude, constant free-flow, etc.) i wouldn't worry about it

what brand reg do you have?

It is a $190 Sherwood Brut.

Thanks

 

[slackercruster]

.

The Zeagles I used for a few dives breathed very wet when inverted; like a whole mouthful of water.

(QUOTE]



What do you mean, 'like a whole mouthful of water'.
Do the zeagles work poorly inverted?