Second Stage Problem?

[Former FLL Now MSP Diver]

Being newly certified, and only using the LDS's equipment up to now, I don't really have a frame of reference for the performance of my own new reg.

Being down at 60 feet, I looked straight up at the surface and the breathing effort became noticably more difficult. Looking away at any other angle the breathing effort returns to normal.

Back on the boat I mentioned to fellow divers. A couple said it was normal behavior for second stages, others said I needed to take it back to the shop for adjustment.

I have a Mares MR12 Axis.

Opinions?

 

[deepocean]

Hi

i had also Mares in the past. (axis and abbys).
These are not the best regs. in my opinion (axis is also not the high end line of Mares) but it should nt be like you are describing right now! Ofcourse it is more difficult to breathe upwards. But the difference should nt be too much at 60 feet! If it is !? defenitly bring it to the LDS for fine tuning! (I think that maybe the problem). And what about your octopus? or sfae second ? (I like to call it BACK-UP, but anyway )
Is this one also hard breathing?

Good luck,
Xerxes

 

[Rick Murchison]

You are describing normal operation for that style regulator.
Rick

 

[TexasMike]

I have done the same behaviour (being vertical and then looking straight up at the surface) and all of the regulators I have used exhibit the same response.

So as Rick said, this is counted as a normal thing.

 

[deepocean]

Not the ATX200!

xerxes

 

[DiveRite-SW]

Discounting a kinked-hose (or something otherwise as odd) or a regulator second-stage out-of-adjustment, it may the simple physics of how a reg is supposed to work.

A second-stage is designed to sense the difference in pressure of a diver breathing from the mouthpiece versus the ambient pressure against the outside of the diaphragm (usually mounted across the boxtop). Therefore when you and the diaphragm are both at the same level in the water, the pressure is the same at both locations and the reg will breathe 'normally'. When you lift your head up, the diaphragm is at a lower (not much, but just enough) pressure to allow it to think there is a mismatch in pressure and cause an increase in the demand-pressure. Conversely, when you tilt your head down, it results in a slight decrease in breathing-resistance, because the diaphragm is now lower than the mouthpiece.
If this is a dramatic difference, there are adjustments to take out this deviation. Only a reputable LDS will know for sure. And some regs have adjustment-knobs on the side that can help compensate as well.