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View Full Version : Pro's & Con's between Nitrox & Air???



Scuba Sheila
01-20-2012, 01:09 AM
We were Nitrox Certified last year at Buddy's, but didn't have a chance to try it out before we left. So, now that we'll be back next month for 2 weeks, we're trying to decide if we want to refresh our Nitrox course & give it a try....or just go with what we know & stick with good 'ol air. We've heard and read many conflicting opinions.....and thought I would ask all you experienced BT'ers out there your opinions!

bcwolfen
01-20-2012, 05:48 AM
Hi Sheila,

There really is no need to refresh your nitrox course. Take a read through your manuals so you remember the formulas and you should be good to go. There is no real difference diving nitrox over air other than you are of course limited to a depth based on your mix.
Buddy dive always has air and 32%. With 32% your Max operating Depth (MOD) is 132 feet. My computer runs on a PO2 of 1.4 so its starts beeping at me at 112 feet.
The other important thing to remember is to make sure you set your mix in your computer before each dive.
Read/bring your manual so you are comfortable doing this.
Nitrox will give you the most benefit between 50-100'. Any shallower and there is not a large benefit to your NDL.
You will also see a big benefit if you are doing multiple dives in a day.
I always find that I can do more dives and feel less tired at the end of the day when I dive nitrox.
When on Bonaire all we dive is nitrox.

ChrisR
01-20-2012, 06:40 AM
Thanks for asking this Sheila, I was in the same boat. I was nitrox certified before my last trip but my wife wasn't so I just stuck with air to simplify things. I am headed back again in April but once again my buddies are diving air. This time I think I am going to give Nitrox a try. My plan is to just stick to air tables and dive my buddies' profiles (While staying above the MOD for whatever mix I am using.) I realize that this eliminates some of the main of the benefits of the Nitrox since I will have to surface with my buddies and sit out their longer surface intervals with them any way.
On the other hand:
1. I will be increasing the safety factor of my profile with reduced nitrogen absorption
2. I have heard a lot of reports of reduced fatigue when doing several dives a day.
3. Maybe I can encourage my buddies to get Nitrox certified when I show them how much sooner I have usable NDL time :)

So, if you go Nitrox, let me know how it works for you.
Chris

ModCecil
01-20-2012, 09:05 AM
I've alway thought that Bonaire is unique in not really needing Nitrox for multi day diving, but having said that, Nitrox is all we dive with on Bonaire. My buddy swears he does not get a dive headache from Nitrox, so Nitrox it is. I do not see a difference in fatigue but then Bonaire dives are not very tiring (for me).

Chris that is a good idea just make sure you set you dive computer's max depth to the Nitrox ppo limit.

CaptNick
01-20-2012, 09:18 AM
Breathing more O2 is good. Not sure of the fatique reduction factor. Nothing has been proven and people defend both sides of the argument. Perhaps more placibo effect. Also at certain depth profile, it increases bottom time.

On the other side, it can be seriously dangerous if not understood or the tables/computer not followed. Plus most shops charge a premium for it due to increased cost of filling.

I choose Nitrox wherever I can find it and esp. prefer on multi day dives. But also ensure my computer is setup and verified before each dive and still carry my tables with me for the 'in the unlikely event' factor.

And dont take the word on the sticker. Make sure you follow protocol and check each and every tank you are picking up. In my last trip I saw Nitrox tanks were lying around and some people were picking them up by just checking fill pressure and not O2 analyzing.. May be they had their own analyser in the truck!

Happy bubbles....

Mork
01-20-2012, 10:55 AM
If you are Nitrox certified and you are in Bonaire where Nitrox packages are the same as air its a no brainer unless you plan on deep diving. Other places charge $20 + per tank of Nitrox. Review your manual and dive Nitrox. The safety factor doing 3-5 dives a day is incredible. All of my friends say they do not experience fatigue like they do on air. I seem to agree, maybe because we tend not to dive as deep.

fraserfraser
01-20-2012, 11:29 AM
Sheila,
thanks also for the topic. I am only air certified at this time but seriously thinking of doing the nitrox thing for the summer. i will be on bonaire this march with my wife. we will dive just air. its more of a pain to get nitrox where we are staying. my wife doesn't see the need. we only do two dives or so a day so not a big deal. when I am there this summer will be doing more like 4 dives a day. When I was there last summer averaging 5 dives a day was diving much shallower than my buddies at the end of the day. they were all diving nitrox, so maybe nitrox is better if doing multi dive days.Anyway i am most interested in this topic.

tursiops
01-20-2012, 11:38 AM
From bcwolfen's post: "With 32% your Max Operating Depth (MOD) is 132 feet. My computer runs on a PO2 of 1.4 so its starts beeping at me at 112 feet."

There is no recreational training agency that recommends 132 feet MOD for 32% nitrox. 132 feet is based on a maximum PPO2 of 1.6, not 1.4. The MOD for 1.4 is 111 feet, approximately, which is why bcwolfen's computer beeps at 112. The beep doesn't mean "only a little farther to go" it means "too deep!"

However, the language is confusing. In PADI, the 1.4 limit is called MOD. The 1.6 limit is called "contingency depth." Other agencies use some different terms.

So, don't get hung up on "what's the MOD?" Get hung up on "what's the deepest I ought to dive with this gas?"

The point is, don't go to deep with nitrox. What is "too deep?" The recreational training agencies say until the partial pressure of oxygen hits 1.4. For 32% nitrox, that is approx 112 feet. That is a depth at which the chance of CNS toxicity (convulsions, then drowning, then death) is VERY unlikely. Beyond that, you are taking a risk. Beyond 1.6, you are in serious jeopardy.

DiveSergeant
01-20-2012, 12:31 PM
Definitely go with the nitrox. We use it with our computers set for air. We calculate our max depth and stay well within the limits. We, too, find better stamina/less fatigue and enjoy the added safety benefits of air computers and nitrox.

As you'll be there for two weeks you should find a noticeable difference. We do two week vacations like you are doing. We do a few things to maintain our energy and safety while on vacation and nitrox is one of the top ones. We wouldn't do straight air unless nitrox is unavailable.

DS

kob
01-20-2012, 12:49 PM
Mel -- excellent post and a good reminder. As I read the first post, I thought to myself "gotta be PO2 =1.6, because I always teach my nitrox students that 28% = 132 ft (at PO2 of 1.4a). And, regarding tables (does anyone dive with tables on rec dives anymore?), set your dive computer to PO2 max 1.4, set your mix = 32%, follow your computer and enjoy !!

coldwaterlloyd
01-20-2012, 02:02 PM
Interesting thread ! After so many positive reviews for Nitrox I am still an Air Head , both in the water and out of the water .
I dive with Nitrox divers about half the time , I have not noticed that they are any less fatigued than myself , in fact I find the Nitrox guy usually the first to bail on dive 4 or 5 of the day .
If it makes you feel good do it , myself ... I love the smell of air at 130 feet ....

Bill K
01-20-2012, 02:40 PM
An interesting thread indeed. Kob, I had to use the EAN32 tables last month in Bonaire because of a bad O-ring seal on my dive computer made by my LDS when the battery was changed. I made two or three dives a day on tables. Stuff happens and you should always be prepared. Both Mrs. K and I dive nitrox in Bonaire but she gets the added safety of using a regular air computer. We rarely exceed 100 feet. I dive nitrox on the U.S. east coast as a way to extend bottom time, altering the O2 centent to never exceed the 1.4 pO2 at our planned maximum depth. As said previously, since the air and nitrox rates are the same in Bonaire, it really is a no-brainer. Enjoy your nitrox.

coldwaterlloyd
01-20-2012, 02:44 PM
I think Bon is the only place with free Nitrox upgrade , here , it is a cash cow .

bcwolfen
01-20-2012, 04:08 PM
From bcwolfen's post: "With 32% your Max Operating Depth (MOD) is 132 feet. My computer runs on a PO2 of 1.4 so its starts beeping at me at 112 feet."

There is no recreational training agency that recommends 132 feet MOD for 32% nitrox. 132 feet is based on a maximum PPO2 of 1.6, not 1.4. The MOD for 1.4 is 111 feet, approximately, which is why bcwolfen's computer beeps at 112. The beep doesn't mean "only a little farther to go" it means "too deep!"

However, the language is confusing. In PADI, the 1.4 limit is called MOD. The 1.6 limit is called "contingency depth." Other agencies use some different terms.

So, don't get hung up on "what's the MOD?" Get hung up on "what's the deepest I ought to dive with this gas?"

The point is, don't go to deep with nitrox. What is "too deep?" The recreational training agencies say until the partial pressure of oxygen hits 1.4. For 32% nitrox, that is approx 112 feet. That is a depth at which the chance of CNS toxicity (convulsions, then drowning, then death) is VERY unlikely. Beyond that, you are taking a risk. Beyond 1.6, you are in serious jeopardy.

Mel is absolutely right. That's what I get for posting in the wee hours of the morning. You should never exceed 1.4 and when I say my computer starts beeping at me, I do mean its telling me to stop and ascend, not carry on a bit deeper.
Most recreational computers use 1.4 as a default setting, on some you can adjust between all the way to 1.6.
Stick with 1.4 and follow its max depth.
In Bonaire there really is no need to go deeper that 11' anyway. You will see more life in the shallower depths.

DiverVince
01-20-2012, 07:27 PM
Um, I say lets make this simple..If cost is not a factor (many places on Bonaire do not charge more for the 32% EA tanks) we will always dive EA. The other factor is depth. Don't go deeper than 100 feet and you'll be fine. And it's quite safe to dive nitrox while your buddy is diving air. Just be sure your computer is set for air and you'll have an additional margin of safety built in.
Obviously if you're planning to exceed the 100 foot depth we will breath air & then on any successive dives that day, we'll stay shallow generally no deeper than 60 feet and will breath EA with our computers set on 20% O2. I find nitrox very beneficial in the warm summer months on Bonaire where our dives are a bit longer.

Scuba Sheila
01-20-2012, 10:13 PM
Great information from everyone and we will definitely need to refresh our memory from our manuals & notes. Fortunately, we are not much into diving deeper than 80ft max, & usually prefer to hang out between 40-60 ft as that's where we seem to find the most sealife with the best light.

My husband was more interested in the idea of the "less fatigue" theory, but it still seems to be a personal thing. We normally dive 3 dives/day (sometimes 4) several days in a row, then take a day or 2 break. I think we'll at least give it a try & see how it goes, but the input from everyone has been great - thanks!

fraserfraser
01-21-2012, 10:20 AM
Okay if I am not Nitrox certified and want to, how would you suggest I do so? I am OW certified from 1986 but no other certifications. Should I do it on bonare,online or at LDS? Will be there in March and July with eye on July for using Nitrox.
Might do AOW on my March trip but its a big might.
thanks in advance for your insight!

DiverVince
01-21-2012, 10:48 AM
Fraser..we did it about 2 years ago at Buddy Dive @ Belmar. Basically they give you the manual & reading stuff & you can read it between dives then complete the lessons. Then you take an "exam". So my advice would be to do it on Bonaire. Plus at the time they were running a nitrox special I believe cost was $100. Now it may be a bit more. As I indicated in the earlier post, I really like EA when the waters warm up in the summer & we have long shallow dives on the reef. In the winter our dives are not as long because of the chill factor. Additionally, make sure you get a good (as in EZ) programmable computer to handle the % of O2 and keep track of the PPO2 which Mel referred to above, (I use the Oceanic Pro Plus 2 which serves my needs well). Staying above 100 feet you should never have a problem with PPO2.

randl
01-21-2012, 11:42 AM
Great thread. My wife and I both dive EA using air computers for no other reason than it is harmless (perhaps an extra margin of safety) and, more importantly, we don't have nitrox computers. We took the EA course in Curacao in 1999 just for the fatigue reducing benefit we had heard about so often. But the PADI EA manual insisted there was no evidence for it. After so many years of EA diving and occasional air diving, we both believe it's real but it's slight. Your experience may vary.

tschamp
01-21-2012, 03:15 PM
Fraser..we did it about 2 years ago at Buddy Dive @ Belmar...
Similar here, but at main Buddy Dive.
What I found "amusing" is that the PADI Enriched Air course uses TABLES, not only in the book, but in the exam at the end. I've not used tables for diving since I got my first dive computer back in the mid 90s. Since I'm technically inclined, it didn't take me long to remember how to use them and I aced the exam.
Some folks might want to review how to use tables to figure your 2nd dive limits after a surface interval, etc, BEFORE doing the Nitrox course...

fraserfraser
01-21-2012, 03:23 PM
thanks Vince. I am staying at Buddy's in July so will check into it.

Bill K
01-21-2012, 07:25 PM
As for the tables, please read my previous reply on this great thread. I spent a week on Bonaire in December using EAN32 tables due to a computer flood. Better safe than not diving. Of course, I got certified on tables before dive computers existed. LOL.

tursiops
01-21-2012, 09:11 PM
PADI Enriched Air class no longer uses tables, although they are still an option; the assumption is that you'll be using a computer. Shop owners tell me that old Nitrox course with tables sold more computers than anything else....

The class can easily be done in a few hours, with only a bit of study in advance. It is well worth doing....especially at the price of Nitrox in Bonaire!

As to fatigue, I am one of those people who really feel the difference. My non-scientific observation is that older, heftier, perhaps less fit individuals remark the most about the mitigation of fatigue....

DiverVince
01-22-2012, 07:10 AM
The comments on the dive tables were spot on..Looking back, I thought at best using them was anachronistic (having been using a dive computer since Orca introduced the Edge aka the brick back in the 80's). But what really confounded my experience, in taking the exam I was given one of those cheap calculators to use. Since I've been using an HP 12C for the last 25 years doing financial calculations, frankly I was lost on the "adding machine" they provided to me, nor did I have any inclination in changing my ways to adapt to what I considered a primitive calculator. Fortunately my wife adapted better to it than I and gave (or should i say hinted at) a few answers to me.

And as far as what to do when/if the UW computer fails, there are several options..1. try & get it fixed..2. use a back up spare..3. Dive very conservatively. After all, if you have a lot of experience under your belt, intuitively you know safe dive profiles. Not the end of the world..

Any way, that's just my personal thoughts on the subject. Bottom line is I'm glad we took the course and believe the extra % of O2 (or should I say less % of nitrogen) can only be useful in avoiding a trip to the chamber. And as far as going below 100 feet, I really don't miss it. And if I do, there's always good old reliable compressed air. As far as mitigating fatigue, well I think the jury's still out on that one, but indisputably the placebo effect is in fact real.

tschamp
01-23-2012, 08:06 AM
One of the few times you "need" to go deep when shore-diving Bonaire is for the Hooker, I believe.
Practically all other dives I did across Halloween were no deeper than the low 60s.