Does Nitrox kill brain cells?

[Sas]

If you generate a table for a PPO2 of 1.4 for mixes 21% to 36% you will do 16 calculations (which you can then use to do 100 dives) compared to doing 100 calculations (one for each dive). Statistically you have a greater risk of error doing 100 calculations than 15. Whether those calculations are more precise is a different story.

Actually the risk of error really depends on one's attention to detail and ability with simple maths formulas.

But I was presuming you meant the calculations were more precise with tables, my mistake when reading your post!

 

[BHB ScubaTroll]

Hey, to be honest... I literally "spin the wheel". I spin my OceanX wheel and look at the numbers. The calculations are on the face of the wheel, and I know they are correct...

So, I really spin the wheel when planning my dives. My gf actually looked at me like I was insane when I said to her, no.. we want 40% for our second dive... It's at 60' (it had been so long since she'd looked at 1.4% that she didn't even realize the numbers)... I really believe everyone gets used to 32 and 36 without even thinking about it..

Now, lately... she's been analyzing our "just top it off with air" dives (shore) in order to trip me up

 

[boulderjohn]

As you calculate your MODs to the precise level of accuracy, ask yourself how accurate was the O2 sensor on your analyzer.

 

[Cave Bum]

Actually wouldn't the formulas give a greater accuracy? I know it did when I obtained nitrox tables to check my calculations for my nitrox course.

If I remember correctly, my PADI Nitrox tables gave 110 feet as the MOD for 32% not 111 FSW/114 FFS. Now, other tables I've seen and used, specifically IANTD, are acurate, but I always wondered about the PADI tables...

Above someone brought up decimal places in the analyzer reading. You always round down to the nearest whole number, leastwise that's what they have us teach...

Also, the tables are based on 1.4 PO2. What if you want the conservatism of 1.35 PO2? There isn't a table that I'm aware of for that. Yea, you could just subtract a few feet, but exactly how many feet at say 82 foot max depth?

Just a thought...

 

[BHB ScubaTroll]

As you calculate your MODs to the precise level of accuracy, ask yourself how accurate was the O2 sensor on your analyzer.

Well, let's see...

I go to the dive shop and order EAN36

The fill station fills with a % of O2 that is supposed to mix with compressed air to get to EAN36

I use their analyzer and the fill comes out 36.2
---

I'm satisfied with that accuracy

 

[Thalassamania]

Measure with a micrometer - mark with chalk - cut with an axe

 

[mikemill]

If I remember correctly, my PADI Nitrox tables gave 110 feet as the MOD for 32% not 111 FSW/114 FFS. Now, other tables I've seen and used, specifically IANTD, are acurate, but I always wondered about the PADI tables...

The PADI tables don't really show MOD. What they show is the PPO₂ for various %O₂ at given depths. So the depth that meets but doesn't exceed 1.4 is the MOD.

Also, the tables are based on 1.4 PO2. What if you want the conservatism of 1.35 PO2? There isn't a table that I'm aware of for that. Yea, you could just subtract a few feet, but exactly how many feet at say 82 foot max depth?

If you consistently want to do 1.35 you generate another table I don't know about the other agencies but the formula in PADI's book is a one variable equation (%O₂). So not sure how many people will know how to calculate it as a two variable equation.

 

[BioLogic]

I use the concept to rough out the answer in my head as a check to the tables I use, the old stand-by 'reasonableness check'. I read the formula but never tried to directly memorize it, as I know my ability to reason it from things I won't forget (air is 20ish% oxygen and more than 1.4 ata oxygen is too much) is more trustworthy than my memory of the formula.

 

[Captain12Pk]

What will the formula give me that a table won't? And don't say that using the formula would let you do 31.325% instead of 31% or 32%. I don't trust the equipment enough to give me that much precision.

What will the formula give you? Well, the knowledge to figure your MOD without needing the tables.
Hey, dive how you like. Personally I don't need the EAN tables. I can do the math on the fly... and if need be, in the water.

If you don't trust your analyzer, I don't know what to tell you.

 

[Captain12Pk]

As long as your tables are initially correct you will have a higher incidence of accuracy using them than by calculating the MOD via formula & calculator each time. Perhaps being a thinking diver means knowing when and how to use tables instead of reinventing the wheel each time.

Please enlighten me. How is knowing how to figure out my MOD reinvnting the wheel?