Potapko
Contributor
Does a tank that has been used for only 100% oxygen need to be re-cleaned after a hydro test?
Post Hydro O2 re-cleaning?
- Thread starter Potapko
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I would say absolutely yes. Many hydro stations recycle water and the risk of contaminant transfer from the water is too great. The safe rule is O2 clean as often as feasible. Thanks.
Phil Ellis
mike_s
Contributor
Heck yes.
If you've ever been to a hydro facility, they aren't real clean typically and they leave the valves off for extended periods to let the tanks dry, etc...
most facilities also typically do other types of tanks also, such as fire extinguishers, welding tanks, etc. Since they re-use the hydro water in the tanks, all kinds of hydrocarbons are cycled through the tanks.
I wouldn't trust any tank from a hydro facility to be clean, much less o2 clean.
I no longer even trust new tanks to be o2 clean, even if the manufacturer says they are. (Just seen too many dirty tanks that were supposedly clean).
I'd take this opportunity also to re-clean the valve and re-pack it in christolube. that way they are both perfectly clean and you don't have to worry about cross contamination.
OP
Potapko
Contributor
Thanks for the responses! There is much about the process I do not understand so I wanted to ask.
Jeff
Jeff
At best, the tank gets filled with tap water with all sorts of potential minerals and chemicals in it even if the shop does not recycle the water.
My local hydro shop is nasty inside. I would definately reclean, although I suspect the hydro shop revalves and fills O2 tanks without any supplementary cleaning. But given the dusty dirty environment in there I even wash my hands after leaving. I wouldn't want to eat lunch nearby, nevermind handle HP O2.
That's a good point. I suspect that the bulk of the tank testing business for most hydro test facilities consists of welding tanks, medical O2 cylinders and CO2 tanks for the beverage industry more or less in that order. Consequently, I suspect about 1/2 the tanks that get tested are used for 100% O2 service and given that the test facility usually valves them after they are dried and inspected, I'd bet that most go directly from the the test facility directly to the fill station and never see anything close to an O2 cleaning.
On the one hand it is reassuring that:
1. Welding tanks don't explode on a regular basis despite being in service, often in grubby and greasy environments for the last 50 years without ever being O2 cleaned, and
2. That medical O2 valves and tanks seem to do equally well despite the tanks not being O2 cleaned and the valves not being cleaned or serviced until they eventually leak - at which point they are more often thrown away rather than repaired.
It suggests that perhaps our NOAA, CGA and NASA inspired fixation on "O2 Clean" is perhaps way over the top compared to what is actually safe in the real world. "Clean room clean" is clearly overkill, but ends up being the goal many shops shoot for due to liability concerns in a world with too many lawyers.
On the other hand, scuba tanks see a lot of use and a lot of fills and it makes no sense at all not to do a reasonable job of O2 cleaning one to be used with O2 at least every 5 years, if not annually.
That is a very interesting observation.
As one of my side hobbies (I am a volunteer ski patrol and EMT) I have handle O2 tanks for many years. In the EMS world and definitely in the commercial welding world they don’t seem to be as concern with handling O2 as in the diving industry.
Maybe the fill stations do a lot of O2 cleaning behind the scenes (I dough it), but EMS and welding regulators are never serviced or cleaned. A dust cap…who ever heard of such a thing? Opening the tank valve slowly…no one ever heard of such procedure.
At the same time they use a heck of a lot more O2 than the Scuba industry and they have been using it for a lot longer. And … they only use pure oxygen, not diluted into Nitrox.
Am I missing something here?
Well I started writing this a wile back and got distracted...you know work stuff. I see that DA Aqua Master already touch on the same subject.
There are a shockingly large number of oxygen fires in industrial and medical oxygen use. I couldn't find the webpage on a quick search, but from my recollection, I think the number of "incidents" is in the multiple hundredsper year. Most are industrial incidents, which are "washed", "hidden", and onlyhow up in the basement files at OSHA.
Phil Ellis
I expect there would be some accidents just by the huge volume. Plus not only they are playing with O2, in the case of welders etc., they are actually playing with fire. EMT, paramedics, nurses, etc. are not much more careful when handling O2. Therefore IMO, numbers in the multiple hundreds per year still seems small compared to the number of hours of use per year.
Some very high risk industries, like ship building, has put a supper effort to work safety and are doing a great job, but they will always be some accidents. The numbers used to be mind boggling. Heck they are playing with oxygen and acetylene and fire and there is grease and paints you name it, all in the same area (sometimes in confined spaces).
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