Nitrox (Enriched Air) just what is it and what benefit does it have for our diving? Nitrox is any blend of air that has over 21% oxygen, hence the tern Enriched Air Nitrox or EAN, with the most common being around 32% oxygen.
The first benefit in diving Nitrox is that by using air that contains less nitrogen we are loading less nitrogen into our bodies therefore at least in theory we are adding a safety margin against decompression illness. With less nitrogen in our scuba cylinders there is even less need to push the limits of the dive tables or our computers. On the regular PADI dive table a dive to 60 feet for 45 minutes leaves us in the pressure group of “S” while on Nitrox of 32% the same dive leaves us in the pressure group of”M”. That is quite a large difference in nitrogen loading.
Which brings us to the next benefit of Nitrox, longer bottom times or shorter surface time. Using our 60 foot dive of before if we look at the regular dive table 60 feet shows a maximum bottom time of 55 minutes and our Nitrox 32% table shows 90 minutes. A huge amount of extra time to spend under water, but not many can make a tank last that long.
So how about shorter surface time? In our 60 foot dive for 45 minutes on the regular PADI table we would be an “S” diver and after a 1 hour surface interval we would have off gassed down to a “G” diver which would allow us only 34 minutes at 60 feet or 54 minutes if we only go to 50 feet. On Nitrox 32% the table is much kinder to our bottom time. If we dive the same 45 minutes and our pressure group is “M” if we want to go right back to 60 feet for 45 minutes our surface time is less than 4 minutes. But since we are safe divers we stay on the surface for 30 minutes which drops us to “H” pressure group and that gives us up to 60 minutes of allowable bottom time.
One last benefit of diving with Nitrox is that you may feel less tired after a day of diving. There is no science that I can point you to, but after 4 or 5 dives a day I know I am less tired