Has anyone had a “free flowing” nose on a rebreather?

[Heat Miser]

Reading through all these examples it does appear to be a more common occurence with the Choptima, and quite possibly I may need to consider an upgrade to the new 6.4L lungs versus the old original 5L lungs.

I have never had this problem in 300 hours of diving on the rEvo, where as it tends to occur every 10 or 15 dives on the Choptima.

 

[PEDiver]

I have never had this problem in 300 hours of diving on the rEvo, where as it tends to occur every 10 or 15 dives on the Choptima.

You can take this with a grain of salt since I'm a newer BM CCR diver, but FWIW, when I was diving my Choptima, it was happening every 1 in 5 dives or so. With my switch to a BM CCR with BMCLs, I have not had an issue (knock on wood). I also feel the BMCLs are more comfortable to breathe. We will see if that trend continues as I build more hours.

 

[InWay2Deep]

This happens to me on my Sidewinder sometimes. I have to make a conscience effort to stop it, never though it could be due to to high of a loop volume as I normally notice that w/ puffed cheeks.

 

[justinthedeeps]

It definitely happens whenever counterlungs get maxed out, and venting is missed.

I think this is common during "rescue ascent" drills when playing the "victim," which is the first time I experienced it.

Seems excess positive pressure turns the soft palate into a OPV

Many chest and side mount CCR's, in addition to positioning the couterlungs further away and/or deeper from the airways, have smaller total counterlung volumes, so hitting that wall could be more likely, in more positions, even from simple changes in trim/expansion.

But what about at minimum loop volume? Can it still happen? Probably yes if the counterlungs are too much deeper than airways.

At how many kPa of positive pressure does this occur?

Guessing respiratory, anesthetists or ENT docs know something about it.