inhale from reg exhale from nose

[ezadel]

Exhalation resistance and therefore the total work of breathing increases when you exhale through a small purge valve on a mask.

sure the total work can increase but is there scientific evidence that this extra amount of work will increase CO2 level in the blood. On the surface beeathing through nose is like breathing from a small valve compared to breathing out of your mouth, however, this extra amount of work ia unlikely to increase CO2 in blood. Again, your theory is logical but unless there is proven scienific evidence correlating the extra amount of work to the extra amount of CO2 i the blood AND you have measured this comparing exhaling in regulator versus valve THEN based on this it falls in a level that will actually increase CO2 then its still a theory

 

[Akimbo]

sure the total work can increase but is there scientific evidence that this extra amount of work will increase CO2 level in the blood.

Only if you want to count a pile of research papers produced by US Navy Experimental Diving Unit and the millions of dollars they poured into it. Discovering that WOB was so important is why they produced the first hyperbaric breathing machine. It was a really Rube Goldberg looking thing compared to the Ansti breathing machines used today but worked. Most, if not all, Scuba regulator engineering departments have one now.

I wasn't stationed at NEDU but they sucked plenty of blood out of us for that and other studies at the Mark II Deep Dive System.

 

[ezadel]

Thanks I am compeltely new to diving and NEDU research I would be very interested in a specific paper discussing just that correlation. I do have a PHD in gas dynamics and have published work on modeling multiphase flow in lung airways, but I have not read much research relating to this topic.
what I was hyposysing happens in case od breathing out from purge valve is that he extra work ends up making the exhale cycle just longer (maybe why it feels more natural and relaxed).. so really no extra force but longer time exhaling due to smaller valve and maybe for a new diver that is a good thing because it promotes slow deep breathing rather than rushing through the air (one thing i noticed is use less air)

 

[Patoux01]

Well, to me the only real reason is that if you ever go to ccr, you're gonna go through a damn lot of expensive helium with such a habit. Adding to that the influence it would have on buoyancy.

I wouldn't make a big deal out of it, in terms of WOB or whatever like that, but it might be best to avoid it as, if you're ever using a "normal" mask, it might feel like it's "too full" with air.

 

[ezadel]

Well, to me the only real reason is that if you ever go to ccr

yea i am assuming whole idea of rebreather is you re breath your air so if you are dumping it through your nose then whats the point , right?

"normal" mask, it might feel like it's "too full" with air.

yep this case would be like using a very bad valve that only opens at much high pressures

 

[vam]

like it's "too full" with air.

Yes, I wear my mask strap fairly loose and use the lower internal pressure to hold a good seal. Sometimes when I let some air into it to eliminate squeeze I have to suck a little back in so it doesn't leak. I've never noticed this during ascent strangely. I never thought about it until now. I'll try to remember to notice this next time out.

 

[TMHeimer]

I have no real opinion on if doing this is good or bad, but assume it's not good to do this. I would think it's easy to break the habit by simply practising on land breathing only with mouth, only with nose, both, in one and out the other. Some have said this is not easy for some people, even on land, but especially on scuba. I can never figure why.

 

[AdivingBel]

Seems posters have given you good reasons why it's not "best practice." Divers do a lot of things that aren't "best practice" that don't kill them. For me, I can get relaxed enough that if I don't periodically remind myself to take some good deep breaths I can give myself headaches, so I tend to shy away from any issues that would promote increased WOB. Given you're relatively early on with your diving and haven't ingrained the habit, it might be a good time to break it. I wouldn't want to be dependent on a purge valve if I could avoid it. Nothing wrong with them, but you may not always have one available (rental mask, break mask and have to borrow one, find a mask you really like but doesn't come with a purge valve, etc.). It would probably be easier to break the habit now than later. All IMHO, YMMV. Good luck.

 

[Patoux01]

yea i am assuming whole idea of rebreather is you re breath your air so if you are dumping it through your nose then whats the point , right?

A rebreather is basically a bag and some sorb, you breathe out in the bag, and breathe in at the other side of the sorb (absorbs CO2). It also needs to add O2 as you're consuming it.
So yeah, if you breathe in from the bag, and breathe out in the water, well, you gotta fill the bag again (which you can, but completely defeats the purpose).


Hope no ccr-freak will get mad at me for making such a simplification

 

[Akimbo]

Thanks I am compeltely new to diving and NEDU research I would be very interested in a specific paper discussing just that correlation. I do have a PHD in gas dynamics and have published work on modeling multiphase flow in lung airways, but I have not read much research relating to this topic.

I would ask the question by starting a new thread in the in Marine Science and Physiology forum. There are several people that monitor that forum who work in hyperbaric research. I've been a guinea pig but am more on the engineering side of the industry. All I ever needed were the conclusions of the studies, target working ranges, and the 50,000' view. All the cellular level bio-chemistry stuff would just be dangerous in my hands.

Have you discovered the Rubicon Research Repository?

BTW, welcome to diving and Scubaboard. It won’t be long before I'm asking you questions.