breathing upside down

[hess]

Does anybody know why regs perform so poorly upside down (ie if Im swimming on my back facing the surface?) Im sure theres a perfectly simple explanation but I couldnt work out the mechanics of it. Any thoughts would be appreciated. Cheers.

 

[do it easy]

It has something to do with the fact that the air in the 2nd stage is pushing the diaphragm upward and acting against the work you are doing to pull the diaphragm inward (or down, in your case).

Of course, I'm not an expert and there might be other factors involved.

 

[Hank49]

It has something to do with the fact that the air in the 2nd stage is pushing the diaphragm upward and acting against the work you are doing to pull the diaphragm inward (or down, in your case).

Of course, I'm not an expert and there might be other factors involved.

I'd say you're an expert on this subject. That's exactly what happens.

 

[Rzrseg]

Mine doesn't seem to breathe differently. I spent a goodly amount of time on my back looking at the tops of 'caves' last week and didn't notice a difference.

If it helps, I'm using an Atomic Z2 with a balanced 1st and 2nd stage.

 

[deeper thoughts]

cadillac of regulators

 

[H2Andy]

yes, it definetely depends on the regulator

my Dacor and SeaElite regs took effort to breathe upside down

the Apeks 50 i have right now ... can't barely tell the difference

 

[spectrum]

In addition to the diaphram esentially going bouyant you may be taking your chest out of the same plane. If you are swiming normally your regulator and lungs are fairly close to the same depth and ir is delivered at ambient pressure.. If you are inverted and somewhat head up your lungs can be many inches of water column below the regulator and your need to overcome that extra depth on your own. You can detect this bobbing vertcally even with a snorkel.

Pete

 

[rescuediver009]

Easy had it right, in that the air inside the second stage housing wants to go up (like all other air under water) and you are trying to bring it down to push on the lever to activate/maintain flow. Some regulator with a higher venturi effect, will negate some of this effect however it is always noticable. Side exhaust/inhale regulators are not affected.
Hope this helps.

 

[Luis H]

Regulators have change a little bit (actually not much) but the physics have not changed at all.

Most of the time you can’t perceive this pressure changes, but they are there. Human perception is extremely unreliable and therefore we require instrumentation for true physical measurements. The opposite argument is that human perception is what matters when it comes to comfort.

From "Let's Go Diving", an Illustrated Diving Manual by Bill Barada, Published by U.S. Divers Co., 3323 West Warner Ave., Santa Ana, CA. Catalog No. 7804-00, Copyright 1962, 4th Printing November 1965, page 29.

 

[Mambo Dave]

Nice diagram and (proper) citation, Luis.