NITROX limitations?

[andreau]

Hi all not sure this is an "advanced" scuba question but here goes.

I have been considering getting Nitrox certified. I like to dive at between 50-80'. Not much deeper unless there is a really spectacular feature or wreck to see. Not afraid of going deeper at all just enjoy hour plus dive times and being able to still see what's there. I have done some research and feel that diving Nitrox on my dive trips will help keep the nitrogen levels down after many repetitive dives over the course of a week. Now my question is what are the depth limitations for say 25-35% Nitrox mix, which I've heard most dive centers use? Am I correct in my assumption that I can dive Nitrox on the normal depth dives and then switch over to regular air for the deeper dives and then back again? I just want more info before committing to the class.

Thanks in advance for the help.

 

[bradells]

Hi all not sure this is an "advanced" scuba question but here goes.

I have been considering getting Nitrox certified. I like to dive at between 50-80'. Not much deeper unless there is a really spectacular feature or wreck to see. Not afraid of going deeper at all just enjoy hour plus dive times and being able to still see what's there. I have done some research and feel that diving Nitrox on my dive trips will help keep the nitrogen levels down after many repetitive dives over the course of a week. Now my question is what are the depth limitations for say 25-35% Nitrox mix, which I've heard most dive centers use? Am I correct in my assumption that I can dive Nitrox on the normal depth dives and then switch over to regular air for the deeper dives and then back again? I just want more info before committing to the class.

Thanks in advance for the help.

Short answer, under 100ft/30m for most recreational Nitrox mixes (some mixtures with less O2 you could go deeper than 100ft/30m). The higher the O2 content, the shallower you must go.

BRad

 

[KeithG]

You can switch between air and Nitrox for different dives on the same day. Just be sure to reset your dive computer to the current mix.

 

[NAM001]

Andreau

To give an idea on the limitations 32% has a max operating depth MOD of about 125-130 and 40% is around 80. Your course will tell you how to calculate your Max depths. Youre correct in regards of reducing the nitrogen content with ean. that will allow you to longer dives in regards to NDL. The price you pay for this is depth restriction and mentioned above. The more O2 the shallower the restriction 50% is 70 ft adn 100% is 20ft. An online course should tell you all yo need to know about ean. It is important that youknow how to use your computer for inputing FO2. You can dive EAN on a computer with air assigned and accept the shorter NDL's adn there will be no prolem as long as you DO NOT VIOLATE THE MOD.

Regards,

 

[andreau]

Thanks brad.

That at is what I understood from the research I've done but always like to ensure what I understood was correct.

 

[drrich2]

Been awhile since I got my Nitrox cert. Off the top of my head, the recommended MOD for EAN 32 was 110' (with a partial pressure of oxygen at 1.4 atm). There was a contingency depth based on a partial pressure of oxygen of 1.6 atm, but the idea was that was not to be dove routinely; more of an emergency basis.

How conservative you (and your dive buddy, if any) choose to be is up to you. I don't go over 110 feet with EAN 32, which seems to be the most common target mix I run across in the Caribbean (actual analysis might be 31 - 33% or so, but EAN 32 is what they're generally trying to offer).

Richard.

 

[andreau]

Thanks KWS.

That is what I read but I always take what I read on the internet with a grain of salt, that's why I asked the question here. I know there are many far more seasoned divers here than myself and if someone posts bad info it is pretty quickly squashed by someone who really knows what they are talking about.

I've also done some reading up on my PDC manual in regards to ean, it's partly the reason I went with my OCi. I'm a very meticulous and safety oriented diver. If I don't like the way something looks or feels I stop and find concrete info. I just wanted a little more info before committing to the class.

Many thanks to all!

---------- Post added April 7th, 2014 at 10:32 PM ----------

Thanks Richard.

That at was another thing I was wondering was what the "standard" mix at places around the Caribbean would be.

 

[String]

If you're ending dives due to air supply then there's no benefit of nitrox. If you're ending dives due to no-stop time then nitrox can help.
Generally comes in handy in the 20-35m range. Shallower than that dives tend to be air limited, deeper than that the mix is too lean to give much benefit.

It's a tool for a specific set of dive profiles that CAN help a lot within those parameters.

 

[Goodtime Adventures]

The most common recreational blends are Ean32 & Ean36. The MOD (Max operating depth) when sticking within the recommended PO2 of 1.4 is 33metres
with Ean32 and 28metres with Ean36 (sorry, I don't work in imperial, but guessing you can work it out!).

 

[Instructor_Tom]

As a mixed gas diver i can tell you that there is no reason to switch to AIR for deep dives within Recreational limits. EAN28 will get you an MOD of 132ft which is the max for recreational diving. Beyond that point we start adding Helium to the mix to ward off N2 Narcosis.

Getting your Nitrox cert is the first step in advancing your diving. As a DM i recommend the folks get there OW, AOW, Nitrox and Deep Diver cert because of the skills learned in these programs will make any diver a much better and safer diver.

Hope this is helpful

T.

And by the way anyone who says that diving Nitrox has no benefits; is not doing long repetitive dives.


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