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Rich Gulley wrote: ~ > > I think you missed my point. Let's try this again from the top. All tanks >> always need to be completely clean, and obviously that means we should >only >> fill from known clean gas sources. I didn't mean to imply that you don't >do >> this. If it makes you feel good to follow some sort of extra oxygen >> cleaning ritual and slap a sticker on it then go ahead, but it doesn't >> change what is actually in the tank. > >I agree, but what do you mean by "extra oxygen cleaning ritual"? A tank is >either clean and rated for oxygen service or not. The whole "oxygen clean" thing revolves mainly around 2 points, lube and o-rings. As far as lube is concerned, almost everybody is using the O2 safe stuff anyway, because it's a much better lubricant. O-rings are really not an issue. The "o2 safe" part of O-rings doesn't really refer to them causing a problem in terms of combustion, but rather that some materials will degrade faster in an oxygen environment than others. Regular O-rings seem to work just fine, and since we replace them all once a year anyway, it's really not that big a deal. There are two other issues, which really don't affect mots people. One is that some dry sealed systems use a whole bunch of lube in the dry chamber, and people have been using silicone for that. My regs are Apeks, which don't need that, so I know little about this. The other is that certain metals are more combustible, such as titanium. Don't use regs that have titanium parts (they'll tell you on the box, because titanium is really expensive and "sexy" .... and dangerous). Some Apeks regs have titanium parts. In reality, very very few tank explosions happen, and I'm sure a lot of "dirty" tanks get filled all the time. Usually, the tank explosions have nothing to do with oxygen at all. There was one recently where the tank was rusted through, and the shop owner filled it even though it was well out of visual and hydro. He died. There is another one that is easily found on the net, which was apparently caused by cracks in the material. Some years ago a bunch of Catalina tanks were manufactured with an alloy that has since been shown to be somewhat less stable than you'd want. Some of those tanks develop cracks in the neck and then explode when filled. Newer tanks aren't made with that alloy, but all the AL tanks are tested using the Visual Plus system anyway, just to make sure. All the oxygen fires that I'm aware of are related to boosting the oxygen, except for the one in San Diego, where the guy was using a titanium regulator. Of course I'm just a diver who's read some books and looked up some stuff on line, I'm no authority on the subject. >I have read what Trey has said. I also think he has more practical knowledge >on this and any other diving related matter. I fallow his advice, it is >beyond sound. But I don't remember him saying to do something easier just >because you can get away with it. I think Trey says basically that putting a sticker on a tank is dangerous, because you are now making assumptions about it's cleanliness, or the contents, and the sticker doesn't prove anything. It basically provides a false sense of security. -Paul B. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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