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S I L E N T I M M E R S I O N wrote: > Frank, > > I do not think that your tanks will "explode" if they are not O2 service. I wont try this! If you are talking about making low fO2 mixes this might be true as you usualy first fill oxygen with low pressure (~450 psi). But when you are doing high fO2 deco mixes chances of combustion increase because of the rising oxygen pressure. The same is true for trimix as you usualy start with the helium or gas thats already in the tank (~1400psi) and than add the oxygen to this (gauge accuracy). > Let's get some feedback from the listmembers. > > 1. Anybody on this list know about any tanks that exploded while filling nitrox? > 2. Anybody not cleaning tanks/gear and still using pp blending? Here in germany all gases containing more that 21% O2 have to be threated as pure oxygen. Pure oxygen has to be in tanks that have a DIN 477 oxygen valve as well as a different TUEV rating (similar to your hydro-test). The idea behind that is that the customer has to be protected from the potential risks of non oxygen serviced gear & oxygen. The laws are so that you can dive and transport gear without that, but when you fill you are breaking the rules. Therefore if you want your tank get filled at a station you must buy a seperate set of tanks and regulators. This stupidity hinders nitrox to become popular. Its rare to find dive shops that are filling nitrox and if they do the price bad. One shop charged as much as $22 for a single fill - thats nearly the price of a whole cylinder oxygen! > 3. Anybody had an oxygen fire due to bad system design/operator error? > 4. Anybody blending oxygen with "normal" filtered air instead of hyperfiltrated? > > Would be interesting information. > > What I do not agree on is that pp blending is dangerous. Blending nitrox or trimix is a simple procedure and most people (all?) get some solid info before starting such activities. Dangerous may be the wrong expression, it might be better to call it controled risk. > Some improperly designed air systems are more dangerous than any pp blending station around. Any high pressure system has its potental risks. I do belive that someone that does pp blending is much more sensible to those risks, too. > One of my favorite misconception I hear people talking about is the rolling of tanks to get a homogeneous mix... Anybody doing that? :-) Not me, but I do let the filled tanks rest a day before analyzing. An if you want to tell me thats not neseccary I recommend that you try this: Fill oxygen, top with air, wait a minute, analyze mix, turn the tank so that the valve faces ground, wait another minute and than re-analyze the mix. Greetings, Frank -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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