Oxygen Cleaning Controversy
First let me state plainly that i am NOT making an explicit statement of fact or setting specific protocols here for oxygen cleaning.
I am only making observations as to the multiplicity of and variations to standards within and outside of the scuba industry.

For instance i observe that:

  • no other industry but scuba requires an O2 clean sticker
you can buy a K bottle, throw an O2 cga 540 valve into the neck threads and get a fill of O2, yet the bottle is NOT O2 clean!!

  • Much attention is now paid to O2 cleaning procedures including "clean rooms".
Little is said in reference to a bottle that has been filled with another gas, be it air or otherwise, that may  or may not be compatible with O2 clean status.
And post cleaning handling of valve orifice or regulator orifice face certainly should deny "O2 clean" status.
An example of some of the more explicit, crosscheck and detail minded standards:
standards utilized by NASA research facility
note:

  • every component is to be individually cleaned, and rinsed, straining rinse fluid through filters and checked for particles. If said
    particles exist, cleaning is to be repeated.
  • The rinse solution shall be a minimum of 100 ml of solvent for EACH component, and greater for larger surface areas
  • visual exam is to be done of the cleaned component under an ultraviolet light, checking for contaminants.
  • white cloth inspection: wiped in two directions with no appearance of contaminants.

I especially like the part that direct my concern regarding O2 clean surfaces and physical contact post cleaning with either human finger
oils or other products:

  • make sure tape does not  touch any cleaned surface

and although protocols requires the cleaned components be packaged in polyethylene which also can become a contaminant, that is
exactly what is required:

  • exercise care in packaging  to prevent abraded or shredded poly to become a contaminant
The standards noted by NASA would indicate quite plainly to me that these items should be protected at ALL times post cleaning.
That the valve opening and face as well as the regulator connection face should be protected at all times from contaminants or it should NOT any longer
be considered O2 clean.

When it is protected it would require that it is done so with an O2 compatible material and that in turn if that safeguard it not likewise protected it also will
contaminate the protected component.

Any tools used to work on or around the components should be non sparking AND oil free. If any old tool out of the tool box is used the component is no
longer O2 clean. I keep a set of wrenches that are used for nothing but O2 manifolds and connections.

To allow for these issues and possible or probable contamination events in any given industry variances, waivers and a wide range of
"determinations" are made to make protocols "reasonable" for a given industry to function and yet safe.
So what is required of the welding industry or construction may have multiple "waivers" or "variances" from the demands placed on the
aeronautical industry. Or even an entirely different set of standards.

Occupational Health and Safety has requirements to safeguard the worker and other agencies and regulations apply to us as individuals.

So what should be the minimum and maximum standards?

My only recommendation would be:

  • follow all local and federal laws.
  • Comply with all CGA standards
  • ALLWAYS error to the side of safety


see also:
"important notice about nitrox"
There are facilities that claim O2 clean room status but what mandates or standard protocols do they follow?
Are they checking under ultraviolet light?
Are they wiping in 2 directions?
Are they straining cleaning fluid through filters and repeating cleaning if ANY contaminants are found?
Are clean gloves worn at ALL times when handling components?

If you are paying a facility claiming "clean room" protocols, I would recommend asking for written standards and protocols of the facility as well as procedural
protocols so that you KNOW what you are getting for your money. Many of the standards carry suggestions only so that all of a noted standard MAY not be
implemented. Make certain you are not cited "CGA 4" etc but written standards in cleaning and assembly for the facility performing the work on your items.