Walter had a good approach to the use of nitrox that I read somewhere. He will use a mix based on the hard bottom, or stick to air when the bottom is deeper than the plan depth. That way in the wall scenario described there is not an issue with the mix. I thought it was a very good approach.
Back to the original hardware question: Nitrox is simply nitrogen and oxygen, like air, but typically with more oxygen and less nitrogen than air. The issues all come from the extra oxygen. As far as equipment is concerned, tanks have been discussed and regs to some extent. In summary, the tanks need to be cleaned for Nitrox use and should have a VIP sticker that indicates they have been cleaned. Most, but not all regs, BCDs, etc. are shipped ready for up to 40% nitrox, but I believe there are just enough exceptions to make the question worth asking when shopping for regs.
It is also important to understand that there are two uses for Nitrox. One is as your primary gas, which is what most of the comments above assume. The other is in a decompression role, where it is common to see percentages well in excess of 40%. For that you will need to have the regs O2 cleaned. This involves changing the O rings to oxygen compatable rings, cleaning throughout, and using oxygen compatable lubricants when reassembling the equipment.
There has also been little mention of computers. If you re buying a computer today, most will support Nitrox mixes up to 50%. Just stay away from the cheapest air only models. If you are considering decompression diving, you're looking at really expensive computers, or tables. Tables are actually much more common among decompression divers than recreational divers. However, you can still use that inexpensive nitrox computer if it has a "gauge mode". As a result, if you are about to take a recreational nitrox course and need a new computer, you should look for one that is both a nitrox computer and has a gauge mode, just in case you want to use it that way in the future. There are other threads on computers, but those features are important to Nitrox use.
The Nitrox course will make all of this much clearer than any of us is capable of in this forum. The basic Nitrox course is one I recommend for every diver, even if you are not considering the use of Nitrox. The material is simply so valuable to your scuba education that I feel every diver should take it.
Edited by Geek, 02 March 2007 - 03:21 AM.
You are right PF I did... I assumed worse case scenario where it was an uncontrolled descent. Their rate of descent would change the approach to the scenario. Still you would only have 2-3 minutes at best at that depth before you had to ascend and still have an ample supply if gas for you and your buddy should things get worse...
