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Scuba Forum / Scuba Equipment / June 2007Oxygen cleaning question
At what % o2 should a reg be O2 clean I am looking at deco'ing on 60% but dont want to O2 clean a reg. Is it safe? > At what % o2 should a reg be O2 clean I am looking at deco'ing on 60% > but dont want to O2 clean a reg. Is it safe? No. I have seen an O2 fire in a reg that was being used with 70%. Take the reg apart, clean it, and use Krytox or Christolube when you put it back together. > At what % o2 should a reg be O2 clean I am looking at deco'ing on 60% > but dont want to O2 clean a reg. Is it safe? Anything handling 40% or more O2 should be "O2 clean". This includes tanks that are being partial pressure filled even though their ultimate mix could be substantially less than 40%. > At what % o2 should a reg be O2 clean I am looking at deco'ing on 60% > but dont want to O2 clean a reg. Is it safe? The industry standard is anything over 40%. Most shops won't fill tanks not cleaned for O2 service beyond that point. While that's probably conservative, it's hard to know just how conservative it is. You really don't want to find out the hard way. I'm curious. 60% seems to be an unusual choice for deco gas. Care to share what made you choose it? Lee >> At what % o2 should a reg be O2 clean I am looking at deco'ing on 60% >> but dont want to O2 clean a reg. Is it safe? [quoted text clipped - 8 lines] > > Lee Single deco gas starting with a 15m stop? I've seen it used that way before... Dan. >> At what % o2 should a reg be O2 clean I am looking at deco'ing on 60% >> but dont want to O2 clean a reg. Is it safe? [quoted text clipped - 8 lines] > > Lee Most shops or gas blenders will only provide Nitrox fills in a cylinder that's in O2 service and with a current test sticker. That because the vast majority of Nitrox blending is done by partial pressure, which involves putting in 100% O2 and then topping off with air. Thus even a 26% Nitrox in a 232BAR cylinder involves putting in 15BAR of 100% O2, so the 'strength' of the mix is irrelevant unless it's one of those rare shops that has constant flow, molecular filtration or can pump pre-mixed Nitrox, which reduces the risks of any ignition. Regards, Tony > Most shops or gas blenders will only provide Nitrox fills in a cylinder > that's in O2 service and with a current test sticker. It varies with the system. I get most of my fills at Fill Express, where they bank the standard mixes including, I believe, 50%. I know of two other local sources that do the same. They'll put up to 40% in anything with a current hydro and visual. The boat I do my spearfishing from, has a membrane system. They could care less about O2 service. A few shops I know of, use a continuous blending system that does the mixing before the gas gets to the tank. They don't care either. I suspect there are a lot more shops that don't put 100% O2 in the customer's tank than most people realize. Lee I am going to a remote location where i will not have access to nitrox fills. I will be doing 10-12 deco dives (40 meters for 40 minutes type of thing) so want to maximize the use I get from one deco bottle. A tank of nitrox at 3 meters will last a while but the higher the o2 the less time so the more dives I get with one tank but o2 cleaning a reg is a hassle so I was looking at the max a reg can safely go to without problems. I know a few techie divers but noone can agree, some sprout laws and regulations and others read books so i thought I'd look futher afield. The tank and getting it filled isn't a problem as I have a o2 clean tank and can get it filled up to 100%. Ta for the help so far >I am going to a remote location where i will not have access to nitrox > fills. I will be doing 10-12 deco dives (40 meters for 40 minutes type [quoted text clipped - 7 lines] > have a o2 clean tank and can get it filled up to 100%. Ta for the help > so far Not a bad explanation. A lot of regulators come O2 compatible. If yours is one of them, you're same all the way up to 100%, which, under the circumstances, would probably be my choice. Further, I suspect you might be able to arrange an O2 refill. There aren't many places in the world that don't use cutting torches for something, and welding O2 is pretty much the same as breathing O2. Lee > >I am going to a remote location where i will not have access to nitrox > > fills. I will be doing 10-12 deco dives (40 meters for 40 minutes type [quoted text clipped - 16 lines] > > Lee I have an old US Divers regulator that kept blowing high pressure seals on 3000PSI tanks. The first stage is so old it was designed for 1800PSI tanks. I started using it on an O2 bottle with a scuba adapter attached. It was NEVER cleaned. The only problem I know is if petroleum based products have been used. Your not supposed to do that with any breathing equipment anyway. What's the big deal? William > I have an old US Divers regulator that kept blowing high pressure seals on > 3000PSI tanks. The first stage is so old it was designed for 1800PSI [quoted text clipped - 4 lines] > been used. Your not supposed to do that with any breathing equipment > anyway. What's the big deal? It's not just petroleum based products you have to worry about. Anything flamable is a risk. Lee > > I have an old US Divers regulator that kept blowing high pressure seals on > > 3000PSI tanks. The first stage is so old it was designed for 1800PSI [quoted text clipped - 9 lines] > > Lee That can not be the problem. Nylon burns wonderfully once you get it started, but the nylon high pressure seat in the first stage never burst into flames. Neither did the rubber hoses or the diaphrams in the second stage. Not all flammable items will self combust in pure O2. There may be other things besides petroleum products, but I have not seen it. William > > > I have an old US Divers regulator that kept blowing high pressure seals > on [quoted text clipped - 19 lines] > > William Its not just the stuff that is supposed to be in the regulator. You said it was never cleaned. If that is true, it is possible that there is a small amount of other flammable material with a low enough flash point in there (primarily the first stage is of concern). All it takes to get a fire going is something that will burn, at a low enough temperature that heat from the oxygen flowing can set it off. And in pure oxygen, any fire that does start will be so hot (and fast) that lots of other things will ignite. Google "adiabatic heating" if you're curious. Obviously, this can happen while the cylinder is being filled. It can also take place inside the first stage, at the instant the seat closes. Proper cleaning of the cylinder, valve and regulator should be done to assure that the risk is minimized.  SignatureArt Greenberg artg at eclipse dot net You really should O2 clean your reg if it will be used for nitrox purposes. All it would take is someone , either you or someone else your with to pick it up and check the pressure on a tank. If it is being partial pressure filled it may be exposed to 100% O2, with all the inherent dangers. It may seem like a shortcut. but it might be fine for a 1000 trips , but only takes one to stuff things completely. (especially if your underwater). >> > > I have an old US Divers regulator that kept blowing high pressure >> > > seals [quoted text clipped - 40 lines] > Proper cleaning of the cylinder, valve and regulator should be done to > assure that the risk is minimized. Just in case anyone is interested (thanks for the help by the way) I'm going to dive twins, using air for 35 minutes at 40 metres then deco on 40% nitrox which will use about 1/3 of a tank. I'll then top up the nitrox tank with air which will give me 30-32% mix which will do for two more deco stops so I get three dives off the one tank. THe place I'll be diving is remote and space is limited see http://www.stirlingsdive.co.nz/trip_report_Kings_2007.htm http://www.stirlingsdive.co.nz/trip_report.htm (look for the kings reports. > I have an old US Divers regulator that kept blowing high pressure seals on > 3000PSI tanks. The first stage is so old it was designed for 1800PSI tanks. > I started using it on an O2 bottle with a scuba adapter attached. It was > NEVER cleaned. The only problem I know is if petroleum based products have > been used. Your not supposed to do that with any breathing equipment > anyway. What's the big deal? The silicone lubricants that are commonly used are almost as bad as oil. > > I have an old US Divers regulator that kept blowing high pressure seals on > > 3000PSI tanks. The first stage is so old it was designed for 1800PSI tanks. [quoted text clipped - 4 lines] > > The silicone lubricants that are commonly used are almost as bad as oil. I guess Aqualube is one of the good ones then because that is what I have always used on it. > I guess Aqualube is one of the good ones then because that is what I have > always used on it. Not a good argument. That's like saying that just because you have always driven 90 miles per hour in the city, it must be safe. It is not just the mix of the lubricant and oxygen. Think back to your elementary school days when Smokey said that there were three sides to the fire triangle ... oxygen, fuel and heat. In your case, you have both the fuel and oxygen sides taken care of. Too fast of a fill will provide the heat. THEN there are problems. SignatureRay Contreras =-=-=-=-=-=-=-=-=-=-=-=-=-=- Webmonkey for: http://www.ossystems.com http://www.bobs-garage.com http://www.coltri-usa.com http://www.rayzplace.com |
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