Subject: Re: how do you clean components for oxygen service?

From: [email-masked] (Jonathan M. Elson)
Date: 25 Jun 1996 18:29:36 GMT

JIMMY ARAKAKI:INDUSTRIAL DESIGN/VISUALIZATION SM2-SFO ([email-masked]) wrote:
: can anyone tell me how to clean hoses, fittings, valves etc for gaseous oxygen
: service?

: I realize that this is potentially dangerous. Folks at welding supply shops
: will not talk about it for fear of lawyers.

: my specific application requires handling oxygen at about 125 PSI.

I am no expert on this, but I am pretty sure the process is done using
a solvent such as acetone.  You wash 3 times in acetone, blowing dry with
filtered air each time.  The 2nd and 3rd wash are with a fresh batch of
acetone, of high purity grade.  The blowing dry is to blow off the last
drops of solvent, so that any dissolved oils don't remain as the solvent
evaporates.  If the material is compatible with oxygen service, ie
stainless steel, then a tiny bit of remaining oil will not cause a massive
explosion, but may ruin the part.  If a tiny bit of oil is on a material
not compatible with oxygen service (ie a metal that can burn more easily)
then you may set a line or regulator on fire, which can be pretty
spectacular.  That is why the double precaution of material and
cleanliness is taken.  Note that some O rings may be porous enough to
absorb oils deeply, so that the quick cleaning bath will not remove the
oils.  These rings may be of a material type approved for oxygen, but if
they are contaminated by oil once, they can never be used with oxygen.
Many oxygen systems now use a lot of teflon seals, which are supposed to
avoid this problem.

---

From: Kevin <[email-masked]>
Date: Wed, 03 Jul 1996 23:37:40 -0700

> Many oxygen systems now use a lot of teflon seals, which are supposed to

Just want to tell you that pure oxygen will burn when it comes in contact with
any petroleum products like oils, grease, and solvents.  There are documented 
cases where a ladies makeup was burnt off her face when pure oxygen hit it.  I 
would call the manufacture that produced the oxygen and ask them what they 
recommed to clean your hoses, fittings, and valves.  If you still can not get a 
answer I would buy new equipment (I know it hurts) because the money you spend on 
the equiment will be cheaper than the hospital and replacing the damaged parts.

Kevin

---

From: Paul Kemp <[email-masked]>
Date: Sat, 6 Jul 1996 14:17:47 +0100

>> : my specific application requires handling oxygen at about 125 PSI.

years ago I had a job assembling & testing valves for high pressure
oxygen service. 

Cleaning/degreasing was done with 1,1,1 trichloroethane.

The Valve stem threads were lubricated with a PTFE film, achieved by
dipping them into a PTFE suspension ("Klingerflon" if I remember
correctly). The valve packing was solid PTFE rings.

I hope that this is of help.

PS. be careful with 1,1,1 trichloroethane - read the safety data sheet
and follow all the precautions. 

Paul

-- 
Paul Kemp        E Mail:   [email-masked]