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Cleaning with Isopropyl Alcohol instead of AcetoneHelpful Member!(6) 

59133 (Aerospace) (OP)
28 Jan 04 9:47
Can anybody help out with this question of which is the better cleaner for a mild degreaser and organic substance desolver?  We use small I.D. Stainless Steel tubing that is ordered from the vendor in a "As cleaned" condition.  The tubing is then formed to various bend geometries and the vendor has been instructed to not use lubrication of any kind when forming and to be very careful of where the parts are stored till shipping.  After we receive the formed tubing, we then use a small recycling pump and storage tank to recirculate Acetone through the lines.  This operation is neccesary because of our product is for Aerospace and Military applications.  A question came up about using Isopropyl Alcohol instead of Acetone.  I have heard that Acetone can leave a residue behind and this could contaminate our units, let alone the cleaning station.  Can anybody help out with this concern of ours?  If Acetone is used as the cleaner, what should follow it in the process to insure no contamination?  Which is better, Alcohol or Acetone ( other than the obvious)?
Thanks.
Helpful Member!  pathfinder9909 (Chemical)
28 Jan 04 18:13
I always use DI water after using any sovent. I run an HPLC and use methanol as a cleaning solvent followed by degassed DI water and find no residual. You can maybe try xylene or MEK, these are some of the strongest solvents around. Most solvents don't leave residuals due to high vapor pressures.
Jeff
Helpful Member!  blonde (Chemical)
29 Jan 04 11:19
IPA would be a better degreaser. It is intermediate in polarity vs. the polar acetone. Now you have to weigh vapor pressures IPA's is greater and less volatile relative to acetone and would require a longer drying cycle or N2/inert gas purge period. I would also implement a QC test to check that your wash is not becomming saturated with the grease/organic. To do this measure out a known mass or volume of the wash solvent into a tared (on an analytical balance good to 0.1mg)foil dish or watch glass, evaporate to dryness on a steam bath, and determine the net mass of non-volatiles. I have no idea what your impurity is so you would have to determine the point where your wash solvent is actually contaminated or leaving a residue rather than removing it. Hope this helps.
Mike
Helpful Member!  moltenmetal (Chemical)
30 Jan 04 7:43
My experience is exactly the opposite of blonde's. Though I understand and agree with the assessment about polarity, I've used both for cleaning/degreasing and find acetone to be far better at actually dissolving and stripping "grease" than IPA.  Non-polar, non-water soluble solvents like toluene etc. are better still.  A three step process of toluene followed by acetone followed by water might be your best bet.  But of course, the result will depend on what exactly the "grease" is composed of.  

The "residue after evaporation" spec of the solvent will determine how much junk it leaves behind after you dry it.  Blonde's given you a good way to measure it if you can't get or don't trust the data from the vendor.   But WHAT the residue is, may be as important as how much of it is left behind.
Helpful Member!(2)  bchoate (Chemical)
30 Jan 04 13:13
bchoate
I would not recommend either solvent.  It seems that your cleaning application is a critical one.  Cleaning for oxygen service is also a critical service.  Dupont has developed 'Vertrel MCA' for cleaning for oxygen service.  If the cleaning method is immersion plus ultrasonic to dislodge particulates and deposits, the Dupont solvent is far superior for greases and oils.  The following link gives some information about this solvent.
www.dupont.com/vertrel/pdf/h65128.pdf
The application is described in the following:
www.dupont.com/vertrel/pdf/h77956.pdf
It is recognized that Vertrel would be have to used in a hood with chilling of the solvent.
Bill Choate
Helpful Member!  PLTPT (Chemical)
10 Feb 04 6:07
Almost any solvent, even oxygen cleaning solvents, will leave some trivial residue. However, acetone, IPA and most light hydrocarbons leave them in the ppb range assuming you dry the tubing with adequate dry nitrogen or similar "clean" dry gas. (Even oil free air is usually not a good choice for drying.) Unless you have an exceptionally critical application it's doubtful that anything will pick them up including a GC unless it's specifically confingured for the materials at very, very low levels. If you are seeing residual acetne, it's probably because you are not drying enough or you have dead legs (places where you can't blow through and the pockets of liquid collect)or you are drying with air.
stevelord (Chemical)
23 Apr 04 16:19
I have found residue problems with acetone too. IPA is corrosive to stainless steel. All solvents have to be bought and disposed of. You might want to try the Minimax steam cleaner www.cleaner.com. This is used by the military for weapons cleaning. The steam jet can be directed down the tubing by connecting to your end fitting. The steam,water and grease coming out is trapped on adsorbent pad which is thrown out.

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