Choosing Between Various Nitrox Classes

[muddiver]

I did IANTD's recreational Nitrox course (& later Adv. Nitrox). It was nothing but formulas (best mix, TOD's, MOD's, Dalton's Diamond....) until the very end end when we were finally able to use air tables & EAD formulas to figure bottom times. By the end of the course, I had a thorough understanding of gas laws, properties & physiology. That helped me to ace the exam.

I was thinking about mentioning the ANDI versions and since you brought up IANTD I will: ANDI is afilliated with some SSI shops and Nitrox training is often inegrated in to the basic scuba class to prep the students for the Level 2 Nitrox course.

The recommended limits under ANDI are only the use of standard mixes of 32% or 36% for Level 1 trained divers and 22% through 50% for Level 2 trained divers. I think that makes a little more sense than deviding 21%-32% and 33%-40%. Using standard NOAA mixes as a beganing diver is simpler than limiting beganing divers to a lower mix percentage. Both ways keeps the PO2 down so depth is less of a factor, just the ANDI method is less complecated.

ANDI has a really cool dive planning tool that combines the MOD, EAD, CNS% and Best Mix into one table called the EAD/MOD Flexable Graph-Chart that is made of a water proof and floppy material.