ppO2 nitrox class question
- Thread starter unwantedsn
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Jack Hammer
Contributor
The charts are right, the second one is just confusing to read. I suspect the decimal differences are most likely from being converted from Metric to Imperial.
1.58 for 130ft at 32%. Chart states 1.57. Is that what you call "flat out wrong"??
Regardless, to have an Enriched Air instructor give the answer of "this is why we use computers, let them do the work for you" when asked to help explain the chart is a pretty poor answer.
All these conversions in the formula and tables are approximate! I don't know the source of the first chart, but it appears to be a slightly more accurate set of numbers than using the formula with 33 ft = 1 ATM. That's because 1 ATM is actually a bit more than 33 ft of saltwater, but everybody rounds off these conversions.
OP
Thanks for the replies. The 1st chart is pulled directly out of the ebook for EAN (40%). Also I was looking at the SSI divelog wrong, I wasn't looking at the correct column, so thank you for the clarification on that. Regarding the instructor comments, it was late and it wasn't a total dismissal of the question but rather a we can look into this later. I don't feel like my instructor did me a disservice, but I figured I would follow up here to get a clear answer.
You are being too kind to your instructor. He should have been able to answer that question in less time than it took to blow you off.
Sylibby
Registered
Which log book is this? I like the idea of chart inserts in the book
OP
This was a separate one and I received when I signed up for the class. On one side it has the ppO2 values, and on the other side it has the CNS clock exposure time table.
I prefer metric.
(Depth/10 + 1) x FO2 = PPO
Divide by 10 is a lot easier than 33.
130ft = 39.624m(1 ft = 0.3048m)
39.624/10 + 1 = 4.9624
4.9624 x 0.32 = 1.5879
If I round up 39.624m to 40m, the calculation is dead easy:
(40/10 + 1) = 5
5 x 0.32 = 1.6
(Depth/10 + 1) x FO2 = PPO
Divide by 10 is a lot easier than 33.
130ft = 39.624m(1 ft = 0.3048m)
39.624/10 + 1 = 4.9624
4.9624 x 0.32 = 1.5879
If I round up 39.624m to 40m, the calculation is dead easy:
(40/10 + 1) = 5
5 x 0.32 = 1.6
Last edited:
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