I just took a nitrox class and my instructor recommended breathing whats left in your tank during surface intervals to increase off-gassing nitrogen. In theory it makes perfect sense but I have never heard of anyone doing this before. I have also heard that breathing low tank pressures can be rough on regulators. So the main question is: Is it a good idea to suck down every last breath of nitrox during surface intervals? Or, is it not worth tearing up my equipment?
Breathing Nitrox Leftovers During Surface Intervals
- Thread starter bendc
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From what I've read you would be wasting your time in regards to accelerating off gassing.
I've not heard that breathing low pressure hurts your reg and don't know why it would, what were you told?
I've not heard that breathing low pressure hurts your reg and don't know why it would, what were you told?
If you are loaded with nitrogen and no O2 is available, then Go or It!
It is probably worst for the tank, so take it down to only 200PSI.
It is probably worst for the tank, so take it down to only 200PSI.
altaskier
Contributor
I'm not convinced that this is very helpful. When breathing out of a regulator, I'm used to taking slow, deep breaths so as to be good on air consumption. On the surface you can take a lot of frequent, deep breaths which I would think do more to promote gas exchange. Also one is often busy with chores for a few minutes after the end of a dive: stowing gear on a boat, or removing gear if a shore dive, etc. Hard to be tied to a tank by a long hose while doing those chores. So I'd rather just spit out the reg and be an air-breathing mammal after the end of a dive.
There is a site we usualy do deco dives on, it's a bit of a hike back to the vehicles so we sit, relax, breathe our remaining 02, debrief........nothing wrong with increasing your access to oxygen.
DevonDiver
N/A
Breathing post-dive O2/rich nitrox has been relatively common amongst the tech community, so the concept has some validity. However, given the nitrogen loading experienced by the recreational diver, coupled with the low % of the 'left-over' nitrox they have, there doesn't seem to be a huge benefit in the practice.
That said, it'd help off-gas 'a little'.... and on very rare occasions, when the statistics devil has you in his sights, 'a little' can make a big difference.
That said, it'd help off-gas 'a little'.... and on very rare occasions, when the statistics devil has you in his sights, 'a little' can make a big difference.
Griffo
Contributor
I reckon you'd gain more benefit from practicing controlling your ascent speed and holding your stop than you would from a few hundred PSI of 32%. You see so many people rush the ascent from the safety stop to the surface. If you're not spending at least a minute going from your stop to the surface, you are going way too fast. People seem to forget that.
The speed at which you breathe really makes no difference in off-gassing (or on-gassing) rates. It seems logical that it should, but it really doesn't. This comes up about every 6 months, and it gets explained each time.
As has been said, this will indeed bring some benefit to you, but with a typical 32% mix at the end of a typical recreational dive, it isn't a lot of benefit and it really isn't needed.
I have breathed both 50% and 100% O2 after dives, though.
HJeffreyM
Contributor
You may be interested in this discussion from 2009:
http://www.scubaboard.com/forums/ask-dr-decompression/305177-nitrox-under-boat.html
I continue to breathe the nitrox after surfacing and on the boat til my spg reads 400-500psi...numerous discussions here (and the physics involved) have made me a firm believer in getting extra Os as long as possible after the dive. Even if there's no absolute benefit on that particular dive, it can't hurt and may have an additional benefit over the course of multiple dives over multiple days. Besides, I paid extra for the gas, I'm gonna use it!
http://www.scubaboard.com/forums/ask-dr-decompression/305177-nitrox-under-boat.html
I continue to breathe the nitrox after surfacing and on the boat til my spg reads 400-500psi...numerous discussions here (and the physics involved) have made me a firm believer in getting extra Os as long as possible after the dive. Even if there's no absolute benefit on that particular dive, it can't hurt and may have an additional benefit over the course of multiple dives over multiple days. Besides, I paid extra for the gas, I'm gonna use it!
Peter_C
Contributor
We have a couple of shore dive sites that require a step hike up after exiting the water. I breathe my 32% while hiking, and until my breathing and heart rate calm down. Darth Vader sounds always make people laugh. *shrugs*
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