Nitrox and PO2

[hdtran]

off topic, but

...snip...

There are some general formulae that you should always remember, which are algebraically intuitive, if you are good with algebra (algebra was invented by the Arabs, by the way, just like numerals).

...snip...

It is believed by many historians that "arabic" numerals, decimal notation, zero, and algebra, in fact, had their roots in India. This was brought to the Arabs in the 9th century, then, translated to Latin around the 11th and introduced to the Europeans.

 

[yknot]

The main benefit to nitrox is lower N2 accumulation compared with air. A secondary benefit to nitrox is more efficient off-gassing during your ascent and safety stop of the accumulated N2 from your dive. As a result, with nitrox you can dive more than compared with air. That makes nitrox a perfect gas for vacation resort diving, where you might dive 3 or more dives in a day, for several days in a row.

Are you stating this all as fact? Nitrox isn't any more efficient to off gas- there is simply less nitrogen, which equates to an air dive of a shallower depth, meaning more bottom time and shorter surface intervals. Nitrox may not mean more time or dives per day. There is also a CNS O2 exposure clock to consider that is not a factor when diving air.

 

[triton94949]

off topic, but



It is believed by many historians that "arabic" numerals, decimal notation, zero, and algebra, in fact, had their roots in India. This was brought to the Arabs in the 9th century, then, translated to Latin around the 11th and introduced to the Europeans.

I think its a fairly safe bet that chess comes from India. The king and the cousellor, the war elephants, the cavalry knights, the chariots, and the infantry are all the same on a chessboard as the way the Indian armies drove Alexander The Great into retreat. The Arabs brought the game back to the Near East, and the Crusaders learned it from them and brought it back to Europe. I have not read anything about Arabic numerals also coming from India, but anything is possible I suppose.

There is a lot of academic material in history that is purely speculative.

In fact, there is a lot of academic material in science that is purely speculative as well.

In both fields of study, we are desperately short of living eye witnesses.

 

[triton94949]

Unless, of course, you wanted to max out your nitrox benefits, where your best bet is to go 40% until 82 feet using a p02 of 1.4.

hehe... your post just reminded me of the "what is the best mixture using a 40% max" type questions on the nitrox test.

If you truly wanted to max out your nitrox benefits, then you would take an Advanced Nitrox course. However for the most part, EAN36 is the richest mix any NDL diver would ever need to consider. I am not convinced that it is smart to teach basic nitrox students about EAN40 for any reason. There are no tables manufactured for EAN40. But you are right, that some nitrox exams ask about the MOD of EAN40.

 

[triton94949]

Kriterian,
Take your formulae and play with them and manipulate them as much as you can. The more you understand the inter-relationships of the different variables the better nitrox diver you'll be.

Exactly! Well said.

 

[WellBelowH2O]

If you truly wanted to max out your nitrox benefits, then you would take an Advanced Nitrox course. However for the most part, EAN36 is the richest mix any NDL diver would ever need to consider. I am not convinced that it is smart to teach basic nitrox students about EAN40 for any reason. There are no tables manufactured for EAN40. But you are right, that some nitrox exams ask about the MOD of EAN40.

Yeah...advanced will give you a different perspective, but then you're also talking o2 clean equipment vs. 40% compatability w/out special prep. and components. I just made the comment the way I did because your post had a strikingly similarity to one question that was on the nitrox exam. That question stuck in my head because I got the answer correct only to have the instructor say it was wrong until he actually did the math and found that his answer key was incorrect.

 

[The Kraken]

To "max out" the benefits of nitrox in typical recreational diving, you're probably going to need to acquire a large volume tank for yourself.

Case in point:
A mix of EAN32 gives a diver a NDL of 60 minutes (if you dive to the NDL) or a recommended dive time of 49 minutes (RDP) at 70 feet.

An average diver with an SAC rate of say .50 and maintaining a 500 psi reserve in an aluminum 80 tank will have only about a 41 minute dive time on that tank.

Using an E8-119 the same diver using the same dive parameters would have approximately a dive time of 65 minutes.

Now the interesting thing is that as the diver gets deeper, the aluminum 80 comes back into its own.

A dive on EAN32 to 90' yields a recommended bottom time of 29 minutes (staying out of the shady areas). Our intrepid diver would get a dive time of 34 minutes out of that aluminum 80.

Lotsa fun stuff to play with . . .

 

[WellBelowH2O]

To "max out" the benefits of nitrox in typical recreational diving, you're probably going to need to acquire a large volume tank for yourself.

Lotsa fun stuff to play with . . .

Ahhh... unless you want to "max out" your benefits on the surface with reduced SIT times instead

You're right, lotsa fun stuff to play with.

 

[triton94949]

...Now the interesting thing is that as the diver gets deeper, the aluminum 80 comes back into its own.

A dive on EAN32 to 90' yields a recommended bottom time of 29 minutes (staying out of the shady areas). Our intrepid diver would get a dive time of 34 minutes out of that aluminum 80...

That is why the 80s and the 72s are still the perfect tank for NDL diving. Especially with nitrox. Especially on boat dives. Especially at dive resorts, where the waters are nice and warm, and where you will be tempted to go back in, over and over again, morning, and afternoon, and night. On the boats, and from the beach at the hotel.

 

[triton94949]

Ahhh... unless you want to "max out" your benefits on the surface with reduced SIT times instead...

I would not recommend shortening the surface intervals. I would keep those at a standard 1 hour between the morning dives and 1 hour between the afternoon dives, with a 2 to 3 hour lunch break in between.

I would recommend taking advantage of the lower N2 loading (compared with the same depths on air, since the reefs are at the same depths whether you are diving with air or with nitrox, depth is samie same).