Tumbling and O2 cleaning

[Sonnylynnvick75]

I'm new, Have my OWC dives March 29th and 30th. I have all my gear including 2 Al80s. I was hoping to convert one of them to be used for nitrox. I had both hydro tested in January. I called my LDS to see what it would take and she said it would need to be tumbled and 02 cleaned. Where on earth do I need to do this?

 

[kelemvor]

Most dive shops should be able to do it for you. Did your LDS say they could not do it?

 

[Sonnylynnvick75]

Most dive shops should be able to do it for you. Did your LDS say they could not do it?

Yeah, they said they didn't do that.

 

[scububa]

This ought to get interesting. For nitrox (<40%) the normal tank maintenance is fine. If you are going to add 100% to partial blend nitrox, you have to treat it as an Oxygen cylinder. If you are going to have nitrox >40%, you have to treat it as an Oxygen cylinder.

Careful about what tumble means. You don't necessarily have to use an abrasive medium to clean the inside of the tank. You can tumble it with a cleaning solution only. (By you, I mean someone that knows what they are doing.) My understanding is that AL tanks don't often need an abrasive tumble. (Not many steel, either.) Some folks think tumbling is over used.

The other element for oxygen cleaning a tank is cleaning the valve and using the correct non-hydrocarbon lubes and o-rings. Again, the standard for below 40% is different than above.

 

[Wookie]

Take it in to Choo Choo divers in Chatanooga. Tell Steve you want it O2 cleaned. Don't say anything about tumbling, just tell him you want it O2 cleaned. Tell him you're going to PP blend nitrox in it. Don;t say too much. There is no reason to tumble (as in tumble with abrasive media) an aluminum cylinder. I've destroyed a number of them by doing it, however....

 

[Sonnylynnvick75]

Take it in to Choo Choo divers in Chatanooga. Tell Steve you want it O2 cleaned. Don't say anything about tumbling, just tell him you want it O2 cleaned. Tell him you're going to PP blend nitrox in it. Don;t say too much. There is no reason to tumble (as in tumble with abrasive media) an aluminum cylinder. I've destroyed a number of them by doing it, however....

Choo choo is who I called and told me "it's a used cylinder which means it needs to be tumbled and o2 cleaned and we don't do that." I spoke with June the manager.

 

[Colliam7]

I called my LDS to see what it would take and she said it would need to be tumbled and 02 cleaned. Where on earth do I need to do this?

I am a little surprised that a shop that actually performs partial pressure blending for enriched air would also not be in the business of cleaning cylinders for oxygen service. Three thoughts:

1. You might want to try contacting some other shops in the area, or at least within a reasonable driving distance. I suspect you might get a different response, either in terms of what is needed, or what they can do for you.

2. Many divers, and shops, do not think that a cylinder needs to be cleaned for oxygen service IF the mix to be put in it is less than 40% oxygen, AND the mix is already blended / banked. There is NOT uniform agreement on this, there are some somewhat contentious threads on SB on the topic, different interpretations of various standards lead people to draw different conclusions, etc. But, it is a fairly common practice to prepare a cylinder for enriched air use by simply putting an enriched air 'wrap', and an enriched air VIP sticker (indicating the cylinder is not oxygen clean) on it. Then, the cylinder can be filled with a banked (already blended) enriched air mixture (e.g. 30 or 32%), and many, if not the majority, of shops that provide enriched air bank mixes for that purpose.

3. As for the 'tumbling' discussion, it also highlights some divergent views. On one hand, there is really no need to use abrasive media - porcelin chips, for example - to clean a cylinder for oxygen service. Many shops use glass beads, and tumble with Simple Green solution, or one of the commercial products marketed specifically for that purpose (such as the GMC solution). However, there are those who feel that even use of glass beads damages the interior walls of a cylinder and do not recommend that approach as a standard practice. (Wookie is one of those, I believe). Our shop's standard practice, for either AL or galvanized steel cylinders, is to use glass beads. But, to be honest, I suspect that simply cleaning with an appropriate solution - put the solution in the cylinder, cap it, and rotate / tumble it - would do the trick. This level of detail probably goes beyond the scope of your interest at this point, but is worth mentioning because of previous comments in the thread.

 

[Wookie]

However, there are those who feel that even use of glass beads damages the interior walls of a cylinder and do not recommend that approach as a standard practice. (Wookie is one of those, I believe). Our shop's standard practice, for either AL or galvanized steel cylinders, is to use glass beads. But, to be honest, I suspect that simply cleaning with an appropriate solution - put the solution in the cylinder, cap it, and rotate / tumble it - would do the trick. This level of detail probably goes beyond the scope of your interest at this point, but is worth mentioning because of previous comments in the thread.

In the manufacturing of a cylinder, when the aluminum is still hot, the combination of the hot aluminum and the mold release agent provides a protective layer to the inside of the cylinder. Sometimes this layer is discolored, sometimes not, but if you remove it, the pores in the aluminum become evident. I only know this because I removed this discolored layer from a pallet of brand new cylinders I bought in 2000. 25 cylinders to a pallet. When I VIPd the cylinders the next year, the amount of corrosion on the inside of the cylinders was disheartening and obvious. None of my many-years-old cylinders had this corrosion, all of them being filled in the same place, only the 25 I'd tumbled.

I had to do 2 things to correct the problem. First, I got rid of the cylinders. Second, we changed the filling procedures so that the face of each fill whip and valve were blown out before ever making up to a cylinder. When filling on a boat, even a stray 1/2 drop of water causes great damage inside a cylinder. Since that time, I O2 clean all of my 80's every year and haven't had a problem. I just rinse them in simple green or blue-gold and rebuild the valves with Cristo-lube. No tumbling necessary.

---------- Post added March 12th, 2014 at 09:06 AM ----------

Choo choo is who I called and told me "it's a used cylinder which means it needs to be tumbled and o2 cleaned and we don't do that." I spoke with June the manager.

Sonny, I'm floored. Something is hinky.

 

[boulderjohn]

I have 9 tanks, all of which I keep in O2 clean condition to the best degree possible. I am a certified inspector and do my own visuals. The insides of my tanks are in beautiful condition. If I decided to stop diving and sold my tanks to you, I can't imagine why anyone would feel a need to tumble them. I can understand why they would not trust the O2 clean level of the tanks and would want to clean the tanks themselves, but I would think a quick visual would show that there is no need for tumbling.

 

[KD8NPB]

My personal thoughts, as landed upon by extensive research into commercial / gov't oxygen use:
1.) Some contaminants can bond to the cylinder walls.
2.) Wash alone will not remove them.
3.) Glass bead is required WITH an oxy-safe detergent.
4.) My detergent is Crystal Simple Green at a 1:100 ratio. This figure is based on US Navy testing. Consumer simple green (the smelly green stuff) may contain trace hydrocarbons.

An aggressive tumble is NOT required for aluminum tanks. Approximately 15 minutes is sufficient, followed by a rinse that guarantees no detergent is left. If detergent is left, then there are probably hydrocarbons left still suspended in the detergent. A shake test is sufficient.