Nitrox - 1.40 or 1.60 PO2?

[Geezer]

My computer is set at 1.40. If I was younger and in better physical shape and etc., I would be OK with 1.60. It all depends on how big a safety margin you are comfortable with. I'm happy now with my Suuntos (conservatism and all).

I have a friend who, in an earlier time pushed 1.80. He is alive to advise others against it, and would never do it himself again (it's that age and conditioning thing). I get enough enjoyment out of colorful little fish on shallow reefs that it is not really an issue for me at this point. The question I ask myself is - would I rather push the limits, or back off, and just enjoy my dive. Much of it is where your comfort level overall is set. I'm sure others would find my dive preferences boring.

 

[rstofer]

I'm a new nitrox diver and having recently made the transition, I was questioned by a friend about what PO2 I was using in my computer. He told me that he was using 1.60 and that I should too.

During my nitrox class, I was taught that the most common P02 was 1.40 and this is what I use.

So the question is this - What PO2 do you use when diving nitrox?

Thanks!

What were you TRAINED to use? I know you did some homework where you had to WRITE the answer and I know it was on the test. You can't claim you weren't told! If you choose to do something else, well, it's just a choice. It is your choice to make and you can live or die based on how well you make it. Just like everything else in SCUBA or, indeed, life itself.

PADI says 1.4 ata for planning and 1.6 ata for contingency (an error condition). That's what I was trained to use and it is what I will use until I am trained for something else. And that isn't going to happen because I am too old to consider advanced techniques.

You will hear all kinds of things from other divers. Always bragging about how they got away with doing something that was incredibly stupid. How deep they dive, how narcosis is fun, how they push the NDLs and PPO2. Worse yet, they write about it; telling the world that all of the training is too conservative and they have a better idea. They may get away with risky behavior forever. Or not...

Make sure you really understand how your computer handles PPO2 levels. My Dive Rite NiTek Duo sounds an alarm when PPO2 exceeds 1.4 ata for MIX1 and 1.6 ata for MIX2 and when the cumulative exposure exceeds recommended limits. The values are not adjustable!

It's your choice: do exactly what you were trained to do OR listen to another diver with unknown or dubious qualifications who promotes a 'better' plan.

Richard

 

[rstofer]

I get enough enjoyment out of colorful little fish on shallow reefs that it is not really an issue for me at this point. The question I ask myself is - would I rather push the limits, or back off, and just enjoy my dive. Much of it is where your comfort level overall is set. I'm sure others would find my dive preferences boring.

As my grandson begins to enter the world of diving, these are exactly the points I make with him. Long shallow dives are the way to go. Lots of bottom time!

Keep the depth to 30 or 40 feet and there are lots of neat things to see. I have hundreds of slides and photos that I have used to entertain him over the years and I continue to make the point that most of the pictures were taken at less than 60 feet and most at less than 40 feet.

Keep it conservative!

Richard

 

[DiveMaven]

I also plan for a 1.40 with a hard limit of 1.60. However, I set my computer at 1.5 so it'll alarm at 1.30 to give me fair warning prior to hitting 1.40. It's nice to have a bit of wiggle room in case there's an emergency and I need a bit more time or depth.

On the other hand, I've only been to 1.40 once diving a wreck in the Bahamas. Most of my time is spent shallower than 65' critter spotting for my husband who has a camera.

 

[TSandM]

rstofer, I disagree with you to an extent. I think it's both important and productive to ask these questions. I think we should all understand not only WHAT we were taught, but where those ideas came from. Understanding the variability and unpredictability of oxygen toxicity, and the high lethality of it, leads to a more mature and independent evaluation of risk and a more consistent control of behavior, in my personal opinion.

 

[fdog]

...interesting thread.

It amazes me that I'm apparently the only one that plans working bottom gas at 1.2.


All the best, James

 

[heelsfaninpa]

I suggest you do some in depth reading of the subject matter and come to your own conclusion.

the K

Thanks to everyone so far. There are many compelling arguments with the use of Nitrox, the risks, and what limits we should live by.

I did take some good advice (see above), and I did do some research yesterday and even went back and read my course manual.

My personal decision, at this time, will be to stick with the PO2 of 1.40 as my hard limit. If I decide to go any deeper than 110ft (ie. 110-130 ft), I will use a leaner mix (~28%).

My original goal when I took the Nitrox course was to maximize my safety. Therefore, I will slowly approach this change with caution and learn from other divers around me (and some of those out here).

Thanks again to everyone.

 

[caver]

I'm a new nitrox diver and having recently made the transition, I was questioned by a friend about what PO2 I was using in my computer. He told me that he was using 1.60 and that I should too.

During my nitrox class, I was taught that the most common P02 was 1.40 and this is what I use.

So the question is this - What PO2 do you use when diving nitrox?

Thanks!

I use 1.2 or 1.4 or 1.6 it all depends on what I am doing.
1.2 for the working part or bottom of a long deco dive
1.4 for recreational dives
1.6 for deco on deco dives

Now since you are a newbie to Nitrox I trust you are doing recreational diving, in that case don't excede 1.4

 

[rstofer]

rstofer, I disagree with you to an extent. I think it's both important and productive to ask these questions. I think we should all understand not only WHAT we were taught, but where those ideas came from. Understanding the variability and unpredictability of oxygen toxicity, and the high lethality of it, leads to a more mature and independent evaluation of risk and a more consistent control of behavior, in my personal opinion.

I guess we can agree to disagree; to an extent. In the end, we both respect the risks of Nitrox and the severe impact of oxygen toxicity. Safety above all else!

My issue is that the OP is a newer diver and quite new to Nitrox. At that level of experience, following the published rules (as a maximum) would, IMO, be prudent. Not that it isn't good to know where the rules come from but again, IMO only, it would be safer to use what the dive industry states (or less), not what another diver thinks is a 'better' plan. Backing up to 1.2 for planning is a great idea! Planning at 1.6 is not!

Discussions that move in the direction of tech diving and involve advanced concepts such as deco diving, or mutliple gas diving do little to help promote safety for a relatively new recreational diver just starting to use Nitrox.

IMO, follow the training. Don't push the envelope.

Richard

 

[heelsfaninpa]

I use 1.2 or 1.4 or 1.6 it all depends on what I am doing.
1.2 for the working part or bottom of a long deco dive
1.4 for recreational dives
1.6 for deco on deco dives

Now since you are a newbie to Nitrox I trust you are doing recreational diving, in that case don't excede 1.4

Caver,
Yes, I am doing recreational diving.

Thanks for replying.