physics-why upside down breathing is hard

[cmalinowski]

All,
I have an older zeagle reg (tech 50d) that a friend gave me when I started diving. In general, it works OK and I can't complain too much. I do have a couple of questions after diving with it for well over a year and about 25 dives:

1. How come when I roll onto my back or go head-down my breathing becomes harder? I am sure that there is some physics lesson hear that I need to understand.

2. Are there regs where breathing is pretty much the same no matter what position you are in? I read the latest scuba diving mag article and review of regs. They have a category about breathing in different positions.

3. When I turn on my back, I end up with a little water in my mouth (< 1/8 oz I'm guessing) which makes breathing all the more difficult. Is this normal? Do all regs have some water seapage?

I have the reg serviced annually no matter how many dives are on it. And, as I said, it breathes OK, but I'm wondering if there is better.

I am thinking that I should probably upgrade, and the oceanic that the mag had near the top of the list looked appealing, but it seems that oceanic does not get a lot of kudos around here and that sort of scares me... but, then again, zeagle does.

Thanks for any help you can provide.

Chris

 

[sharpenu]

Your lungs are deeper in the water column than the second stage of the reg. The extra water pressure on your chest is not being properly compensated for because it is not being "sensed" by your reg.

 

[rndboulder]

Here is a partial answer to your question: It is a diagram of the effects of diver position on breathing. It shows both single hose regulators and the older vintage double hose regulators. The basic physics has to do with the regulators position relative to the center of volume of the lungs and the variance in water pressure. -Ryan

http://vintagescuba.proboards2.com/index.cgi?board=instruction&action=display&thread=1071253464

 

[Uncle Pug]

When you are heads up vertical in the water your lungs are much lower with respect to the regulator than when you are supine horizontal (on your back.) But it is easier to breath vertical than supine so the position of the regulator in relation to your lungs isn't the answer.

However the position of the diaphram in the second stage with regard to the water column does seem to make a difference. When your second stage is facing up the air inside it is exerting an upward force on the diaphram offsetting some of the downward force of the water column... making it breath harder.

Try this sometime: get vertical and with out changing the position of your regulator vs your lungs tip your head forward reg facing down and breathe... then tip your head backward reg facing up and breathe. Can you tell any difference? Why?

My zeagle/apeks T50Ds all give me a shot of water when I turn over on my back or go head down. I suspect it is the way the second stage traps some water at the bottom of the case when in the normal position and that is what I get when I invert.

 

[boomx5]

My zeagle/apeks T50Ds all give me a shot of water when I turn over on my back or go head down. I suspect it is the way the second stage traps some water at the bottom of the case when in the normal position and that is what I get when I invert.

I changed the exhaust valve diaphram to a Mares and it doesn't do that anymore.

 

[Uncle Pug]

Hey Scott... that is good to know since I go supine on a regular basis. Now I won't have to gargle saltwater each time.

 

[pennypue]

My zeagle/apeks T50Ds all give me a shot of water when I turn over on my back or go head down. I suspect it is the way the second stage traps some water at the bottom of the case when in the normal position and that is what you get when you invert.

<stupid grin> And this is what I use to relieve dry mouth. <big stupid grin>
So if you see me doing a headstand now you'll know why.
<and now I know why it works>

 

[StSomewhere]

I changed the exhaust valve diaphram to a Mares and it doesn't do that anymore.

I have Apeks TX50/40s for regs (long!!! story), the only thing that annoys me is the leakage when diving on my back (i.e. looking at the surface). Can you enlightment about what you are doing? Part numbers appreciated. PM is fine if need be. Thanks!

 

[boomx5]

I have Apeks TX50/40s for regs (long!!! story), the only thing that annoys me is the leakage when diving on my back (i.e. looking at the surface). Can you enlightment about what you are doing? Part numbers appreciated. PM is fine if need be. Thanks!

I had my LDS change out the exhaust valve to a Mares one. I read it, or heard it somewhere I just don't remember. I'm not sure of the part number, but I'll see if I can track it down.

 

[Dragon2115]

1. How come when I roll onto my back or go head-down my breathing becomes harder? I am sure that there is some physics lesson hear that I need to understand.

That I can't answer. I'm sure it has to do with the construction geometries of the regulators, their position in the water column with relation to each other, and onhuman physiology.

2. Are there regs where breathing is pretty much the same no matter what position you are in? I read the latest scuba diving mag article and review of regs. They have a category about breathing in different positions.

I can't speak for other brands or models but I notice very little difference at all with my Atomic Aquatics Z-1.

3. When I turn on my back, I end up with a little water in my mouth (< 1/8 oz I'm guessing) which makes breathing all the more difficult. Is this normal? Do all regs have some water seapage?

I read what I believe is the same Scuba Diving magazine article and based my purchase decision partially on it when I bought the Z-1 a few weeks ago. It said the Z-1 was dry in all positions. Where I like poking around looking for critters being able to hover motionless in any orientation is important to me. So far I have to agree with the article, I haven't been able to find a position where the reg gets wet, and it breaths easy in all positions too.

Btw, if by any chance you do end up deciding to get a Z-1, put the M1 exhaust kit on it. It was recommended to me here and it was well worth the extra $20. I tried it in both configurations and it does make a dramatic improvement in bubble interference if you like to look forward while swimming.