Nitrox??

[FWADIVER]

depends on your local, its only $2 more for me to dive 32% so the only time I dont is when the MOD wont allow it or the dive shop lent his analyzer to someone and I would have to wait for a fill.

 

[ThomasScherrer]

The SDI Computer Nitrox course is done online, do not require any dives,
and you get to know all there is to know about nitrox,
it is 99$ and you get a nitrox ceritification card, with this you can get access to the magic nitrox gas
at your local filling station / shop.
welcome to the club

 

[Dive-aholic]

With all due respect, Rob, aren't the air tables or a computer put on air settings, generally more conservative (shorter dive times) than those reading, or set to Nitrox anyway? As long as MOD's are not violated, the O2 clock is no where near limits & the tissue Nitrogen loading is not as high as the computer or tables read,... isn't that a bit on the safer side? I realize that if you start a dive series like that, then it would be wise to adhere to that same planning for the entire duration of the series. Sure,... on shallower dives, you may be cutting your dives shorter than really neccesary & the advantages may not be that much, maybe even near negligable. I am in no way saying it eliminates all the hazards of DCS,... only not diving will do that. I frequently dive Nitrox with air tables or my computers put on air settings(weekends at the quarry). Depending on my buddies & my mood, I may do dives anywhere between 25- 100';doing 4- 8 dives for the weekend. If I do decompression diving there, I will, at times, even base my decompression schedule as if I have air in my back gas with O2 as final decompression gas, even though my back gas is 32% Nitrox. I will do the little bit longer stops as prescribed & finish up on my 20' & 10' stops, with the O2 (very rarely more than 15 min. total decompression time). I will even take the more extended surface intervals prescribed by the air tables or computers set to air, to keep things even safer. So, given that (less nitrogen), how is that not a bit safer from a DCS standpoint? The math seems to suggest it.

It's a myth that nitrox is safer than air. Using nitrox while planning dives on air tables may give you shorter NDLs, but you are also ignoring the other aspects of nitrox such as CNS loading. Every nitrox student and instructor manual I've read states nitrox has no increased safety over air.

 

[k ellis]

when you discuss nitrox one thing goes without saying. It has very little scientific data to back up most of the claims made for and against it. Most of the aspects are theoretical though some aspects have been proven to be correct.

Oxygen has healing effects so its only natural to assume it would be carried over into the world of diving. So with this in mind the energizing effect it has on patients and so forth one would assume it would provide a more enegergetic feeling post dive. I know I feel more relaxed and more energetic post dive on nitrox.

Now with that said Nitrox serves a couple of diffrent purposes and one being the 50' to 110' range as previously mentioned so it would allow significantly more NDL time. Below 50' and Id honestly say 20 - 50 foot it would serve more as a buffer then a safety margin. Take for example an instructor who may be taking out several divers at a time and thus place him in the water for well over an hour or more at a time it would allow a significantly reduced surface interval for perhaps a break for lunch or rest break. In the shallower depths it would serve the shorter surface interval more then it would the NDL as these would not be overly significant at the normal training depths most instructors opt for anyway (typically 20 - 30 feet)

Now when you start asking if Nitrox is worth it or not you best be ready for some people coming at you with some flame throwers as some people just flat out think nitrox is a waste. Dont let this deter you though as I would recommend taking the class and dive both on air and on nitrox over a period of time and come to your own conclusion!

 

[tstormdiver]

It's a myth that nitrox is safer than air. Using nitrox while planning dives on air tables may give you shorter NDLs, but you are also ignoring the other aspects of nitrox such as CNS loading. Every nitrox student and instructor manual I've read states nitrox has no increased safety over air.

I did not ignore those facts (MOD's & CNS), read my questions again. Perhaps it is because I referred to the CNS clock as the "O2 clock" (your moniclature is a much better fit). I apologize if that caused some confusion. Of course those risk factors would have to be monitored seperate of the tables or computer in use, as long as the diver is aware of where they stand with them. Typically in recreational diving, most divers will not even come near the CNS clock limits (thus why I put that monitoring the CNS clock to be important in my original questions), unless they are doing a large number of dives, very long recreational dives or dives that are constantly pushing the PPO2's. Those types of dives are propbably rather unusual, though I won't say they don't or won't happen. Technical diving,.. yes,... that's a whole other ball game when it comes to the CNS clock. I would guess guess you have not read SSI's Nitrox manuals (as that is what I teach). They do state that breathing Nitrox using air based tables &/or computers does give a larger safety margin (not that SSI is the know all/ end all to scuba instruction, by far), when all other risk factors of Nitrox (MOD's, CNS clock) are managed. The only thing close to what you state I've read about Nitrox is it is not proven to make a diver feel better than diving on air, as it is very subjective.

 

[Dive-aholic]

I would guess guess you have not read SSI's Nitrox manuals (as that is what I teach). They do state that breathing Nitrox using air based tables &/or computers does give a larger safety margin

No, I haven't read SSI's Nitrox manual. I wonder what they know that IANTD, PADI, and TDI don't know.

 

[drrich2]

I recently wrote out a summary to discuss nitrox with a friend on mine who might take the course. I'll paste that here, in case it's helpful. I did not discuss the issue of oxygen build-up toxicity (aside from the maximum operating depth issue), or the fact that scuba tanks for nitrox need to be dedicated to it (you don't put nitrox in the tank you usually use for compressed air). People often like to use nitrox on live-aboards or shore-diving in Bonaire where they do a lot of repetitive diving. Apologies in advance for any mistakes.

Most scuba divers breathe compressed air. Air is assumed to be 21% oxygen, 79% nitrogen, the the other components are negligible.

When you dive, the high pressure at depth causes dissolved nitrogen levels to build up in your blood. This can cause a narcotic-like effect, with slowed thinking and reaction time, for some an effect somewhat like the 'buzz' of alcohol, and for a few people even hallucinations. Some can get intense anxiety.

When you come up from depth, the pressure decreases and dissolved nitrogen may convert to the gas phase, nitrogen bubbles. If these bubbles are few & tiny, they will be released into our lungs and exhaled, and body nitrogen levels will drop over time. If you have too much nitrogen in your system &/or go up too fast, you can get joint pain, paralysis and other effects.

That's diving with air.

Some people dive with 'enriched' air, a.k.a. nitrox.

Usually when people speak of nitrox (which is basically a nitrogen-oxygen mix), they're referring to compressed gas that has a higher concentration of oxygen than room air does. The most commonly used form is EAN 32, which has 32% oxygen and 68% nitrogen.

Mixing nitrox is more complicated and troublesome, and thus more expensive, than compressing air, and people use an analyzer to check the % oxygen in case a mistake was made, so why would anybody use it?

Well, first let me tell you what nitrox does NOT do.

1.) Nitrox does not prevent the narcotic effect of deep diving (at least we assume it doesn't). Oxygen is presumed to be roughly on par with nitrogen for narcotic effect, so you can get slowed, buzzed, over-anxious, etc...on either air or nitrox.

2.) Nitrox does not let you breathe slower & make your tank last longer. You are driven to exhale by CO2 build-up in your blood, not by your body running out of oxygen. I once read that exhaled air has around 17% oxygen. You will go through a tank of nitrox just as fast as an air tank.

3.) Nitrox doesn't let you go as deep as air - oxygen build-up in the blood under high pressure can cause seizures and kill people if they stay too deep for too long.

Debatable benefit: Some people think they get less fatigue diving with nitrox than air, but this report is inconsistent, unproven and in doubt - may be a 'placebo' effect. But this is why it got the name 'Geezer Gas' (since old divers liked it).

Soooooo, why would anybody use this stuff?

Well, it does slow the rate of nitrogen build-up in the blood, so you can stay down longer, or make a few repetitive dives in a day with shorter surface intervals. If you're somewhere like Bonaire where getting in 3 or 4 dives a day is practical, that can be a good thing.

At dive resorts in Bonaire, nitrox is often a free upgrade - costing no more money to use than air.

The MOD (maximum operating depth) for EAN 32 is 110 feet. Since the recommended depth limit for recreational scuba diving on air is 130 feet, people go through air a lot faster and great depth and there's usually little reason to dive over 110 feet anyway, the depth limit thing is not a problem on most dives.

 

[tstormdiver]

No, I haven't read SSI's Nitrox manual. I wonder what they know that IANTD, PADI, and TDI don't know.

I dunno. I guess it is something we can agree to disagree on.