Why get Nitrox certified?

[Dirty-Dog]

Matt, the danger of Ox Tox exists with air, just as it does with any other breathable combination of gases. EAN21 (that would be...AIR) just has a deeper MOD than Mixes containing > 21% O2.

The solution is very simple. With any mix normoxic or hyperoxic mix, you figure out how deep your dive is going to be, add a buffer, and plan your gas to keep your ppO2 no higher than 1.4 throughout your dive.

With the appropriate mix, the difference in no-stop time can be huge. If your gas consumption is low enough that you're pushing the NDL on your dives, then using nitrox will let you stay down longer, so you're not srfacing with 1500PSI still in your tank.

If your SAC rate is not low enough for NDL to be your limiting factor (and thus, you won't see any actual increase in bottom time), there are still reasons to use nitrox.
Consider that since you're taking on less nitrogen, you'll have less to offgas. That means shorter surface intervals. Longer no-stop times. Shorter no-fly times. Possibly (though this is not based on any solid research) a reduction in fatique.

 

[DevonDiver]

Or have shorter surface intervals, or more dives per day, or a greater safety margin.

Personally, I prefer to keep a minimum surface interval of 1hr when using nitrox on repetitive dives... so I suppose it depends on what duration surface intervals you'd otherwise be planning.

Nitrox provides a greater 'safety' margin in respect of nitrogen absorption on a given dive profile... so less risk of DCS. However, when taught as a class the 'theory' answer is that, in general, "nitrox isn't safer than air" because it brings additional hazards, not present with air in recreational depths (fire, explosion and ox-tox).

Matt, for many novice divers, nitrox doesn't bring many appreciable benefits. Gas consumption and/or guided dive profiles/limits tend to dictate dive duration - so extended bottom time in respect of NDLs isn't critical. Most novice divers (diving within recommended limits) don't come close to NDLs regularly... low air drives them up first. This is especially true if diving on a dive computer - where multi-level profiles dictate the NDL.

In that respect, I think it is more beneficial for a novice diver to spend cash on a dive computer, than a nitrox course. Of course, there's no reason not to get both - if funds allow it.

That said, if diving actual square profiles where there is no option to multi-level (i.e. more common with wreck diving, than reef diving) and doing deeper dives (25-30m)... and doing repetitive dives in those profiles... then nitrox is invaluable - especially on the repetitive dives, where residual nitrogen really starts to accumulate and impact on NDL.

 

[yarik83]

I got nitrox certified 4.5 years ago as I was learning my scuba. Effect was almost instantaneous. I come out of dives filled with energy and not tired. I have not noticed longer bottom times to be honest but that is because most of my dives are drift dives where I do not more much and I got my breathing well under control. I also never dive more than 2 tanks per day so technicality of repetitive diving does not apply to me. Buut... having nitrox certification under my belt and diving with nitrox when applicable puts me well ahead of table curves and I like to have some room in my dive tables.

 

[redacted]

There is no real reason to have some minimum number of dives before nitrox cert. I believe some OW courses now include nitrox at the same time for a small added expense. Of course, there may be little benefit until a diver's consumption rate gets to the point where dive become NDL limited rather than gas limited

 

[beaverdivers]

The best reason is to reduce your risk of decompression sickness ( DCS ).

 

[RTee]

Being Nitrox certified puts you in the driver's seat...to use it or not based on the diving you are contemplating doing.

At some dive locations, if you are certified, dive ops will include it for free as part of your package. Locally, 32% fills are the same price as air. Because most of my rec diving is conducted at 110 ft or above, my GF and I will normally carry EAN 32 in our tanks. She has also upgraded to HP 100 cft tanks therefore greater bottom time over all the depth ranges we normally dive.

Nitrox becomes very useful when your gas usage starts exceeding your NDL for given tanks, more so when starting using larger capacity tanks as you can now extend your NDL due to the lower nitrogen content of the gas you are breathing. Down at 100 ft, breathing 32% allows you to add 10 mins to your NDL (30 vs 20 mins). Second advantage is when doing repetitive dives especially if the second one is relatively deep as well. I recalled doing back to back dives over two different wrecks locally at depth 100 and 90 ft respectivelly. Me and my GF were using EAN32 and some of my friends were diving air. It became very clear during the dive planning for the second dive that, following a 1h 34mins SI the only thing we would be doing together would be descending down the line because their NDL calculated from their DC was hovering around the 9 mins mark. As a matter of fact, they did one quick orbit around the wreck and then had to capture the ascent line mid-water while my GF and I did manage a 37 mins dive including a bottom time of 30 mins and never getting a NDL lower than 4 mins (and I am diving a Suunto DC).

The dive ops I have been using in Coz the last two years also segregates EAN certified and air divers so everybody in the group is relatively on the same NDL schedule. I used the word ''relatively'' because during my last weekly vacation there, I did 21 dives including 16 over a four day period which meant I could be very well be on my third dive of the day while somebody was on his first. Using EAN and adapting my dive profile accordingly enabled me to properly manage my NDL, remain with the various groups from start to finish and still conduct dives averaging 60 mins.

I dove a similarly busy schedule durign my last trip to Bonaire...40 dives over two weeks using EAN 32 as well.

Seizure risk...already covered in previous posts. If you dive within the promulgated guidelines, I think you have hundredfold chances of getting hit by a car crossing at a busy street intersection or being involved in a car accident than experiencing it, especially being the very cautious type of diver image that you are projecting and the type of diving you will be conducting.

In my case, I got my EAN certification before my AOW and I ensured that my 16 yr old son did his as part of his AOW. This way, when we dive together (like we will be doing in Key Largo this summer) we all do it on the same schedule.

 

[drbill]

Well, once I finally reach true geezer status (three months from now?) I may indeed decide to get Nitrox certified. My reason for not doing it so far is that it costs a hefty premium out here on the island and given the number of dives I normally do each year, it would be cost prohibitive. Of course the number of dives itself would lead one to think Nitrox would be a better alternative than air.

I will undoubtedly get Nitrox certified soon (after 50 years of diving air) to add an extra margin of safety on trips where I am doing heavy repetitive diving. These days I rarely do more than two a day while here on Catalina and I no longer dive almost every day.

 

[TSandM]

The virtues of Nitrox really show up on multiple dive days, and for dives in the middle recreational range (60 - 100 feet). The only real downside of Nitrox is possibly having to O2 clean your tanks, and having to analyze your gas before using it. If you are doing recreational dives and keeping to recommended ppO2s, oxygen toxicity just isn't going to be an issue. And since the MOD of 32% at 1.4 is 111 feet, there is very little need to push your ppO2s, because there are very few things between 111 and 130 that really have to be seen

It is difficult to prove that Nitrox is any safer, probably for two reasons -- one is that DCS is extremely rare to begin with, and showing a decrease in frequency of something which is rare is difficult to do. The other is that people who dive Nitrox often dive it for increased bottom time, and if you run your dive out to your no-deco limits on Nitrox, you're no better off from a nitrogen loading standpoint than you would have been at the end of your shorter limit on air.

You are quite right to note that Nitrox probably offers little benefit to the beginning diver, as their dives are at least supposed to be kept shallow, and gas consumption is almost certainly going to be the limiting factor on their dive time, rather than deco status. But there is no harm in learning early, and the reviews of decompression theory that come with a Nitrox class probably aren't a bad thing, either.

As far as group diving goes, it IS an issue when you have divers on different gases. I would not be terribly happy to have the captain ask me to buddy up on a deeper dive with someone on air (but then, I don't really like unknown buddies on deep dives, anyway ). This is one of the reasons why standard gases make sense, is because they put everybody on the same page with respect to deco -- AND with respect to depth limits. When our group went to Cozumel, we all dove 32% all the time, which meant that we never intended to do some of the deep dives there that people write about. It worked because we had five people, and thus most days, our own boat.

 

[Bob DBF]

The best reason is to reduce your risk of decompression sickness ( DCS ).

I have heard this line of thought a number of times, and if you are using air tables to limit your dives and breathing nitrox as a buddy of mine does it will give you a margin between the NDL of the air and the NDL of the nitrox. If you are using nitrox at NDL, I see no reduction of risk because you are at your N2 limit even though it may take you longer to reach that point. Is there something I am missing?


The boat I dive has Nitrox and I will use it especially for multiday trips. For my local diving using 2 may be 3 tanks I don't notice enough difference to offset the cost of keeping three tanks O2 clean and a long drive for a fill, If banked nitrox becomes available at a reasonable cost I may change my thinking.



Bob
-----------------------------------
I may be old, but I’m not dead yet.

 

[Peter Guy]

The OP asks "Why get Nitrox certified?"

To which my immediate answer is, "Why not? What is the downside of getting Nitrox certified?"

One (and I think the only reasonable one) response is that it costs money -- generally around $100 - $125 (materials and course). If that is too much money to spend to get a little more education then don't get Nitrox certified.

BUT, if paying 1 1/2 Scuba Bucks is within the budget, do it -- especially if you can a course from an instructor who is willing to go beyond the cookbook course. That is, find an instructor who is going to discuss decompression theory (at least as it applies to recreational diving); who is going to discuss gas management (which generally puts a lie to the notion that "Nitrox will extend my bottom time" since more dives are controlled by supply rather than N2 loading); in other words, an instructor who is going to instruct.

Good luck.