Tanks do not have to be Oxygen clean for nitrox < 40%, if a membrane system is used to fill the tanks. You only need O2 cleaning if partial pressure blending is used. If you do have your cylinders O2 cleaned then every airfill whether nitrox or not has to be to the nitrox standard, if you want to maintain them O2 clean. I suspect for recreational diving, if you don't have access to a membrane filling station, don't bother with nitrox. You can recover from the bends, but you can't survive a seizure underwater! The added expense and hassle is not worth it for me. If I go passed a membrane station I get a nitrox fil otherwise I stick to air.[/QUOTE]
Your statement doesn't make much sense. Although membrane systems for Nitrox is nice, it is not the only way to get a Nitrox mixture. The Nitrox can also be pre-mixed using a mixing stick & then stored in a bank system or can be partial pressure blended within an O2 cleaned cylinder. My shop offers Nitrox through both partial pressure blending or a pre- mix done with a Nitrox mixing stick. I will occaisionally put hyper clean air (the same air that is mixed for partial pressure blending) into my nitrox cylinders, if I just want air or a more diluted mixture. By doing this, I do not have to worry about the O2 cleaning being compromised. If the OP is properly trained, he/she should be trained to analyze their mixtures. Analysis should be done before using ANY Nitrox cylinder, regardless of the method of how the Nitrox is made or blended. The OP should also be taught & know the MOD for the mixture they are using. That being said, by analysis & Knowing the MOD, Nitrox being created by any method, should be safe for recreational use, as long as the known limitations of the mix are adhered to. As long as the MOD for the analysed miture is followed the chance of siezures from Oxygen Toxicity should be absolutely minimal.
