...//...As the coursework becomes increasingly more difficult, specifically, physics and equations for Nitrox, is there any advice as far as understanding all of this new information? ...//...
Yes, play to your own strengths.
Explanation:
I have a lot of experience helping a diver with learning differences.
Let me guess, you look at page 95 in your NAUI Nitrox Diver book and you freeze.
With that in mind, I'd like to see how many nitrox divers
(that don't teach) can still come up with the EAD calculation. No, Really!!!
OK, start turning all those cards back in if you can’t!
What I have found, through assisting my friend, is that you must to be able to
talk your way through it. Front to finish, include all the stumbles. When you get it right, you write it all down. Please know that memorizing complex equations works just long enough to pass a test, nothing more.
Let’s do a "talk-through" as an example:
EAD. This is going to be long and will most likely only make sense to you. But you are why I found and re-typed this.
Equivalent Air Depth. Stupidly confusing name. Is this the depth where air would give you the same oxygen toxicity as the nitrox mix in question or is it the depth where air would give you the same nitrogen narcotic effect as the nitrox mix in question? Wait, no, maybe it has to do with nitrogen dissolving in tissues and the bends...
What are we talking about nitrogen or oxygen??? Ambiguous. Meltdown.
Recovery:
When I see EAD, I think EA
ND. Equivalent air
NITROGEN depth. Ok, nitrogen. Totally FORGET OXYGEN for this problem. That would be a MOD problem. Which begs the question, why is MOD the “maximum operating depth”, is it due to oxygen toxicity or nitrogen. Ha! Again, stupidly ambiguous. It isn’t you, pal. The naming conventions suck.
Back to the problem, focus. EAD.
(think EAND)
I’m breathing a mix that has more oxygen and less nitrogen than air. Only worried about nitrogen for now. I’m breathing something that contains less nitrogen. So, breathing nitrox at some given depth, what different depth would give me the same bad effects of nitrogen if I were breathing air?
Maybe deeper, because nitrox has less nitrogen in it? No. They are asking it the other way around, what is the depth where air would give me the same effects that I’m now getting by breathing nitrox at my present depth.
So where I’m breathing nitrox, I’d have to be shallower to get the same nitrogen effect if I was breathing air. This is because air has more nitrogen in it. So my answer is that the equivalent air (nitrogen) depth has to be some number that is shallower than my real, true, depth when breathing nitrox. Ok, I need to come up with a shallower depth.
Now that my thinking is straight, time for some math.
The fraction of air that is nitrogen is either 0.78 or 0.79 depending on how you figure. I use 0.78 as the 1% difference is a mixture of a bunch of odd gasses that don’t count here due to the fact that they aren’t nitrogen. If in doubt, read the law of partial pressures.
Every 33 feet of seawater gives me another atmosphere of pressure. You know that. For EAN 32, 32% is oxygen. Stupid naming convention, we are using this mix just to reduce nitrogen, not to increase oxygen. Nevermind, just another distraction. The nitrogen fraction of EAN 32 (1.00- 0.32) is 0.68 nitrogen. The oxygen fraction is 0.32, thus its name, EAN 32.
So now, for any depth where we are breathing our nitrox mixture, we can come up with a new depth (EAD) where we get the same nitrogen effects if breathing air. Being the same, we can equate them.
[(RealDepth/33) + 1] x 0.68 =[(EAD/33) + 1] x 0.78
This is just ATA x FractionN2 on either side of the equation. ATA's are the same as you learned in OW, Nitrogen fraction is given in this course.
Just plug in the numbers and solve for the only non-number, EAD.
Example:
What is the EAD for EAN 32 at 100 feet?
[(100/33) + 1] x 0.68 = [(EAD/33) + 1] x 0.78
Plug in and grind it out, step by step:
[4.03] x 0.68 = [(EAD/33) + 1] x 0.78
2.74 = [(EAD/33) + 1] x 0.78
2.74/0.78 = EAD/33 + 1
3.51 = EAD/33 +1
3.51 -1 = EAD/33
2.51 = EAD/33
2.51 x 33 = EAD
82.8 = EAD
So to answer your OP:
Do this exercise cold with your own stumbling blocks. Same for all the other calcs you have to do. Write them all down on their own sheets, save, and review them. Replay the entire scenarios from scratch now and again. You will be able to come up with any calculation that you need just by thinking it through.
Best,
lowviz