Nitrox question

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Less then 60 feet on a single tank I don't see a benefit vs the cost. 60 to 100 heck yeah use Nitrox if possible. Doing a week long diving vacation for sure. Doing two shore dives on the weekend, meh.

Part of my problem is that Dolphin does partial pressure blending so I'd have to get my tanks cleaned. And I'm pretty sure their safe air isn't $2/fill like the normal air.

Nitrox at Dolphin isn't too expensive. It's only $18 to fill my dubs. And you won't get a better blender than Bill. That dude's a fill genius.
 
Just from a recent dive here's one real world example.

This last week we did a shore dive to beto's reef (on HP100's (well I had a 130)) and had a max depth of 120 fsw, with a total dive time of 58 minutes. The dive was basically drop at bird rock, out past sea mount on to betos. Then once there we swam to the northern tip and then back towards shore following the bottom on the way back. We all were on EAN32, and still managed to hit a 1 minute deco obligation that cleared before ascending past 45 fsw. One of the divers however who was new to Nitrox diving wore a second computer set to Air.

Upon surfacing in the cove with our 3 minute safety stop that Air computer still had 18 minutes of deco that wasn't cleared. I don't believe that had that diver been on air there would have been 18 minutes of gas left in their tank.

I have to say I personally like Nitrox for some situations as well. If I am taking out a tour and not intending on going deep, for peace of mind ill still dive nitrox in the event that I end up surfacing faster than id like for whatever reason. I will also dive Nitrox if I know later that day ill be driving somewhere 2000 feet or more in altitude just to avoid any micro bubbles.

I would like to some day do more research in the diving before flying logic. I mean most commercial flights are pressurized to 8000 feet. Now no where have I ever seen anything mentioned in learning materials about what altitude you can't drive to after diving, so is the no diving before flying rule only to cover you in the event of a cabin pressurization failure? I guess thats for another topic at another time, not trying to hijack this one.
 
I also dive nitrox now almost exclusively. On boat dives I'll usually pack 32 & 36 for the deep and then not-so-deep 2nd dive. On shore dives or on days when i'm not sure about the depth i'll bring two 32% tanks. The only problem is on some dives the 32 can get you close to your MOD of 111 fsw with a standard 1.4Po2. Its easy to get deep on a lot of boat dives so you have to really keep track of your depth when on nitrox.
 
32% fills either cost $7 or $7.50 each (I can't remember). When you buy a card of 10 fills at Any Water Sports.
 
Figure the cost of two dives in Monterey (driving, parking, eating, EVERYTHING).
If an $8 Nitrox fill (Aquarius Del Monte fill card) gets
you more time, you may very well have a lower per minute cost than the
time you get on air. More importantly, you get in more diving.

Me, I dive nothing but Nitrox. It's not worth the trouble of keep air tanks
around. We usually get 32 at Aquarius Del Monte, occasionally if we
don't get fills on the way home and have go to AWS or Pacific Divers,
we'll get a some of the tanks (we have nine) filled with 40 which is really
great on the shale.
 
"close to your MOD of 111 fsw with a standard 1.4Po2"
I don't understand this statement, could you dumb it down or should I wait to take the class and they'll explain it? :)
I got the 111 feet salt water part.
 
Nitrox (32%) really comes into its own in the 70-100' range (where you gain up to 50% more NDL time). For dives past 60', I'll generally take 32%, shallower, I'm fine diving air (assuming no dive marathons).

If you need nitrox and want to learn the basics of DIR, take GUE-Fundamentals instead of UTD Essentials, since the former includes a nitrox cert.
 
Maximum operating depth for that mix. At 1 atm your po2(partial pressure of oxygen) is .21 with air. A 32 mix your po2 is .32 at 1 atm. You must convert the fsw into atm and add 1 for the actual atmosphere. So 111/33+1=4.36. 4.36x.32=1.39. Some people use 1.4 I personally use 1.6 put not for super long exposures. I only dive nitrox on hard bottom.
 
I have no aversion to air on shallow, minimally repetitive dives (a 2-dive boat in Hawaii? Air is fine), but I NEVER fill my tanks with air in anticipation of that. I always fill my own tanks with 32% (who knows where you will next dive?), and don't stress it if my dive happens to only be 40ft.

"close to your MOD of 111 fsw with a standard 1.4Po2"
I don't understand this statement, could you dumb it down or should I wait to take the class and they'll explain it? :)
I got the 111 feet salt water part.

One of the important considerations of what your maximum depth should be is the physiological effect of the partial pressure of a gas, in this case, oxygen. As you descend from the surface, which is 1 atmosphere (1ATA), to 33ft (2ATA), 66ft (3ATA), etc., the air becomes denser, and the amount of each gas you take in is higher for each breath. Oxygen is toxic at high enough concentrations/exposure, if you're exposed to too much oxygen for too long you can develop a bunch of nasty symptoms, including convulsions and loss of control (resulting in drowning) - that's oxygen toxicity.

Air is 21% oxygen at the surface. That's a partial pressure of 0.21. At 33ft, or double the atmospheres, it's still 21% of the total mix, but the mix is twice as dense, so the partial pressure doubles to 0.42. At 66ft, ppO2 goes to 0.63, etc.

With nitrox, the fraction of oxygen is higher than air, and so the ppO2 at any pressure is also higher. For 32% nitrox, it's 0.32 at the surface, 0.64 at 33ft and 0.96 at 66ft. Once you get above ~ppO2 1.4, the risks of developing these toxicity symptoms increase--the risk is still small, but the consequences if it happens are severe. So one aspect of determining the maximum operating depth of a gas is in keeping the ppO2 below this risky level. Most people use a ppO2 of 1.4, which is about 111fsw for 32% nitrox. I keep it 1.2, which is a little less than 100fsw.
 
https://www.shearwater.com/products/teric/

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