Oxygen clean after hydro

[cavehunter]

I went into LDS to have two HP 100 hydro tested and the owner said that he would also have to oxygen clean them. He said that it was standard practice to oxygen clean a cylinder that was nitrox prepped after the first hydro, so it boiled down to oxygen cleaning once every five years. Does this sound right? I know that a tank doesn't stay oxygen clean forever but every five years even if it had been filled with nitrox and oxygen compatible air from the same dive shop.

[Gary]

Sounds like standard paractice to me. Unless you are hydroing the tanks with O2 clean fluids it would be hard to be sure nothing was introduced to that tank in the process. The shop doesn't do the hydro themselves I'm sure so O2 cleaning would seem to be a justifiable requirement for O2 service.

If you are just filling with premix <=40% you wouldn't have to get O2 service clean though but its not a bad idea anyway.

I know my steel tanks don't always come back from O2 cleaning as clean as they were before (occasional flash rust is a possiablity) so I can understand the hesitance in cleaning them unnecessarily.

[metaldector]

The folks that do hydros around here also hydro fire extingishers, tanks that hold other gases for welding, etc. They use the same water over and over so it is likely that contaminents are left in any tank hydro. Standard proceedure to Oyxgen clean after hydro seems logical.

[DeWayne]

If your cylinders are being filled via partial pressure then you should O2 clean them every year when you have the visual done on them, more frequent if you suspect contamination. Coming back from hydro I would suggest going through with the O2 cleaning even if you are using premix blends, i.e. no partial pressure fills, to take care of the rust and any other contaminants that may have been introduced. Some hydro shops are better than others, but most will return your cylinders after they have been filled with water and improperly dried. I have yet to hear of a steel cylinder coming back from hydro without a fair bit of rust in it.

[curtschu]

I was surprised the outfit in Orlando that my LDS must have dried them. They came back clean as a whistle no rust. Of course since I was bugging the hell out of them to get my tanks back they didn't sit around empty for very long

[Genesis]

I O2 clean any cylinder that has the valve off when I'm not sitting right there watching it, or if anything I don't know the status of goes in there.

Hydro qualifies.

I've never seen a PST steel come back completely clean from a hydro - the place around here is good if you have it put on your ticket ("PLEASE INSURE CYLINDER IS DRY!") about doing a decent job of drying it, but a little orange flash rust is expected. Depending on how bad it is I may or may not remove it, but I always O2 clean the cylinders when I get them back.

In most cases I O2 clean both tanks and valves annually, especailly if they get filled by anyone other than myself during the year. It only takes one guy who's less-than-careful to get something in there you don't want and have an accident, and since I PP mix myself, I don't want to be the one who finds out about it the hard way.

[Dell Motes]

Interesting. I just had several steels and alu hydro 'd.
They turned them around in one day, cleaned and dried the inside, and coated the internals of the steels with an O2 compatible sealant that prevents the flash rust................
Them babies are ready.

[Kenny P.]

Interesting. I just had several steels and alu hydro 'd.
They turned them around in one day, cleaned and dried the inside, and coated the internals of the steels with an O2 compatible sealant that prevents the flash rust................
Them babies are ready.

Dell,
You're very fortunate to have such a hydro. facility at your disposal. I think they are the exception and not the rule. Our local guy does a fair job, but nothing like you describe above. I always clean customer's, as well as my own cylinders, after hydro.
Thanks,
Kenny P.

[Dell Motes]

Yeah, no doubt some are better equiped than others.
I was willing to drive an hour for the service, as I had quite a few tanks to hydro...........

[DeWayne]

Yeah, no doubt some are better equiped than others.
I was willing to drive an hour for the service, as I had quite a few tanks to hydro...........

Any chance we can get you to share the location of the hydro shop Dell? As Kenny mentioned, I think they are the exception to most and I am sure that anyone who might be close enough to them would likely have an interest in using them. I would drive an hour or two for the type of service you reported.