Cleaning the Chamber

[Jake Wells]

I have bought a few conflat flanges off Kurt J. Lesker a few months ago but just today i realized you should not touch CF flanges with your bare hands because their is a risk of oil contanimation from your skin. Could acetone be a good product for cleaning the chamber if you touched the flanges with out protection? And if its not what would be a good solution?

[Jerry Biehler]

Acetone is fine for a first wash but you need to go over it with something non-polar like mineral spirits. Acetone holds water and water is evil. And no methanol!!! I used methanol to clean a valve and I was outgassing for days.

You can also pre-bake parts before assembling and that will help too. But with most guys doing fusors it is not a big deal since operational pressures are pretty high when it comes to what conflat fittings are normally used for.

[Jack Puntawong]

In case you are using Viton gasket like me, you should be using Isopropyl alcohol instead. I'm guessing that Viton will somehow react with acetone and destroy the seal. Check this chart out, I think it'll help you decide on what you should use:

http://legacy.shurflo.com/pdf/industry/CCChart.pdf

Jack Puntawong

[Louis_Haeberle]

I have done some microfabrication and optics work in cleanrooms. The procedure we used for cleaning parts is as follows :

Scrub the part using 1% "Micro-90 Substrate Soap for Critical Cleaning Applications" (as far as I can tell it's just expensive dih soap with ammonia added)
Sonicate the part successively in : Micro-90 solution, deionized water, acetone, isopropanol for 10 minutes each
Dry in a clean oven at around 60C.

For high-vacuum use, after drying in the normal oven, a higher-temperature (100-120C) drying in a vacuum oven was used. Also, in fusor use, I don't think particulate contamination is much of a worry, so just soaking and slight agitation should be fine instead of ultrasonic cleaning.


--Louis H.

[Chris Bradley]

just today i realized you should not touch CF flanges with your bare hands because their is a risk of oil contanimation from your skin

It's really a bit OTT at this amateur level. A polish-up with a clean lint free cloth will be fine. Any volatile residues remaining will not take long to pump off. There's no need to go below 10^-6.

If you feel a need to clean finger prints with a solvent, IPA is just fine.

I actually use 1mm 'thick' (it's very thin!) closed cell packing foam with a little IPA sprayed on it. I tear a strip off it and use that as a 'cloth'. It's very cheap in big rolls and is incapable of leaving any lint behind. I do this mainly to ensure there are no fibres or dust that might lie on the seal and compromise it. Finger prints would not really concern me, though of course it is better to avoid touching any such mating parts.

[Jerry Biehler]

Just make sure you use industrial grade IPA (Isopropyl Alcohol) and not drug store "Rubbing alcohol "stuff. The drug store stuff often has oils and other crap in it you dont want in a vacuum chambers. Most hardware store should have the "real" stuff. Or just pick up a jug of mineral spirits.

[Jake Wells]

Would it be fine to clean the chamber with acetone and then go over it with IPA?

[Jack Puntawong]

You can use either acetone or IPA to clean the chamber up. You don't need both. I mentioned IPA just incase you want to clean up a viton gasket. We use alcohol based solution because it evaporates after cleaning and not outgas while we are under vacuum.

Jack Puntawong

[Chris Bradley]

Acetone attacks a surprisingly large range of materials. Unless you have heavy oily contamination, I'd personally say you should stick with IPA.

[Jerry Biehler]

Acetone is not real good for oil, it is about right in the middle polarity wise. More polar solvents should be used on grease and oil.

IPA is good for a generic wipe down to remove light oils but it also holds water, that's why you want to wipe down after with something much less polar like xylene or toluene.

http://macro.lsu.edu/howto/solvents/Pol ... 0index.htm

[JohnCuthbert]

Jerry,
Water is a very polar solvent- it doesn't do a very good job of dissolving oil.

[Jerry Biehler]

OOps, mistyped, that should have been "more non-polar"