Nitrox Questions

[oddible]

I'm a new diver and took a trip to Belize this spring where I got my PADI Nitrox cert. My last 2 dives of the trip were on Nitrox and the dive op owner mentioned as we were departing - Oh you're diving on Nitrox? You'll feel great after the dive!

It was true, my wife and I did feel great after the dives. Is this common on Nitrox dives? Is there that noticeable feeling from nitrogen loading that after a week of diving we would notice that much difference from a couple of Nitrox dives at the end?

Now that we have our Nitrox cert, we're trying to figure out how to use it - given dives at a depth where Nitrox is appropriate, when do most people utilize Nitrox? Every dive? The first few dives in a trip? The last few? If you're doing 3 dives in a day and only used Nitrox on one of them which would be optimal? (Is this even a reasonable question?)

Just trying to get some ideas about how other folks use Nitrox and a more nuanced understanding of the benefits.

 

[metaldector]

Nitrox is any mixture of enhanced gases where the oxygen level is greater than normal 20.9%. Normal air has 20.9% oxygen and 79% nitrogen (normal air with traces of other gases). As you increase the 02 content you decrease the nitrogen content. Nitrogen is an inert gas that does nothing in your metabolism but fills the empty spaces in your tissues under pressure (water pressure). When you surface your body off-gasses through breathing. Should you participate in strenuous activities after diving you may force this gas from you body through the tissues not respiration and have skin bends or worse. Tissues saturated with nitrogen tend to make some people very tired, nitrox makes others feel less tired. When should you dive it? Depends on your depth, time, temperature, age, and number of dives you plan on doing a day. Personally, I dive it always. I’m older, I see it as an advantage to my metabolism. It gives me shorter surface intervals too

 

[Zaixon]

From my understanding its best to use it on the first few dives a day if you are using it on multi day dives without going over your CNS clock/Oxygen Exposure. Then later in the day use normal air to level it out. Something to this extent was covered in my class (correct me if i'm wrong)
Or if not doing multi day dives then it seems best to use it all the time. I just took a Nitrox course as well and it seems like diving with it will only benefit you if you do it correctly.

 

[oddible]

Nitrox is any mixture of enhanced gases where the oxygen level is greater than normal 20.9%. Normal air has 20.9% oxygen and 79% nitrogen (normal air with traces of other gases). As you increase the 02 content you decrease the nitrogen content. Nitrogen is an inert gas that does nothing in your metabolism but fills the empty spaces in your tissues under pressure (water pressure). When you surface your body off-gasses through breathing. Should you participate in strenuous activities after diving you may force this gas from you body through the tissues not respiration and have skin bends or worse. Tissues saturated with nitrogen tend to make some people very tired, nitrox makes others feel less tired. When should you dive it? Depends on your depth, time, temperature, age, and number of dives you plan on doing a day. Personally, I dive it always. I’m older, I see it as an advantage to my metabolism. It gives me shorter surface intervals too

Hehe, thanks for the book answer - I read most of what you've indicated in the course. My questions really relate to how people use Nitrox in multiple dive scenarios. The answer that I seem to be hearing is that once people get their cert, they always dive nitrox if the dive profile permits it.

 

[on_two_wheels]

I agree....use it whenever you simply want to OR when you need to. If I'm doing a deep dive, it's a must. I've been narced on air and have no desire to do so again. Nitrox reduces the risk, emphasis on reduces...doesn't eliminate it. Always be aware of and strictly adhere to MOD.

I just did 3 dives on 32% and my deepest was 70 fsw max (first dive). The 2nd and 3rd dive was 50 fsw max. Still, I do feel less tired just after a dive. After my 2 hour, rush hour traffic drive home I still went to bed early, though.

If you are doing 3 dives and were thinking of using nitrox on one dive, base it on the profile. If you're doing a 100 fsw dive, use nitrox. It will reduce your saturation, increase safety (as long as within MOD), etc. Personally, if I'm using nitrox, I use it all day. One time, however, I started on regular air and noticed I got close to the red on my computer for saturation. So the last dive I switched to nitrox just to add a little more time.

 

[PfcAJ]

I agree....use it whenever you simply want to OR when you need to. If I'm doing a deep dive, it's a must. I've been narced on air and have no desire to do so again. Nitrox reduces the risk, emphasis on reduces...doesn't eliminate it. Always be aware of and strictly adhere to MOD.

I just did 3 dives on 32% and my deepest was 70 fsw max (first dive). The 2nd and 3rd dive was 50 fsw max. Still, I do feel less tired just after a dive. After my 2 hour, rush hour traffic drive home I still went to bed early, though.

If you are doing 3 dives and were thinking of using nitrox on one dive, base it on the profile. If you're doing a 100 fsw dive, use nitrox. It will reduce your saturation, increase safety (as long as within MOD), etc. Personally, if I'm using nitrox, I use it all day. One time, however, I started on regular air and noticed I got close to the red on my computer for saturation. So the last dive I switched to nitrox just to add a little more time.

Nitrox does not reduce narcosis. Some estimates put oxygen as actually More narcotic than nitrogen, however some of it is metabolized, so the actual affect isn't certain. Another point is that the increased oxygen has been linked to CO2 retention in diving. CO2 is ridiculously narcotic.

There is no safety benefit from nitrox in regards to narcosis.

 

[CamG]

Greetings Oddible and Nitrox is a valuable tool that is not difficult to use but the rules must be followed carefully.
Personally I dive Nitrox on almost every dive taking advantage of the least amount of nitrogen I can. Even for deeper dives I use the best mix equation to determine the percentage of O2 for the mix.

I dive on average 3-4 dives a day on a given week end and I can tell a big difference from air. I just did a month or so ago several Nitrox dives then 3 more air dives.
I was noticeably more tired due to nitrogen than when I dive Nitrox on all the dives.
When using Nitrox make sure you have your computer set correctly to track your O2 levels. Never exceed your O2 clock or your PO2 it will can be very dangerous.
I would review your manuel and keep the knowledge fresh in your memory.
Do not allow yourself or wife to become complacent about your Nitrox use.

Always be the one to check your own gas and be sure to verify the mix and MOD.
Nitrox is as safe as the diver using it!
Good luck and safe diving!

CamG Keep diving....Keep training....Keep learning!

 

[on_two_wheels]

Nitrox does not reduce narcosis. Some estimates put oxygen as actually More narcotic than nitrogen, however some of it is metabolized, so the actual affect isn't certain. Another point is that the increased oxygen has been linked to CO2 retention in diving. CO2 is ridiculously narcotic.

There is no safety benefit from nitrox in regards to narcosis.

I've heard this as well. However, I've been narced on air and have NEVER been on nitrox. I'll continue to have faith in personal experience. I know it could just be luck but so far, I've had NO problems with nitrox at 100-115 feet. I'll stick with the nitrox at that depth.

 

[MaxBottomtime]

People get narced on dives, then not narced on the same dive the next day. There is no evidence that nitrox reduced narcosis, nor fatigue. If divers actually felt better after diving nitrox, they would have the same experience if they dived shallower on air. You don't "feel better" after a thirty foot dive any more than you would after a forty foot dive. Too many people seem willing to believe anything someone with something to sell tells them.

 

[on_two_wheels]

Perhaps placebo effect. Still, if I feel better after doing something, then that something made me feel better. It doesn't matter what someone else's experience is. If I eat something and it makes me sick, I can say, "Don't eat that...it'll make you sick." Then you eat it and it doesn't make you sick. So if you tell me a study of X number of people showed no benefit to nitrox after a dive, that doesn't mean a whole lot to me as an individual. Only my personal experience matters to me.

Seems many people are willing to accept random study results as applicable to everyone. Again, I'm not saying nitrox DOES reduce fatigue in everyone....I'm only saying I notice a difference in me.