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Metals compatibility with Deionized water

In the past I have been using only plastic, 316L stainless, or Nitronic Stainless while working with electronic grade DI water in my cleaning process. I am now in a situation where money and time are tight and I may be willing to compromise. A rotary union manufacturer offers an off the shelf product which includes 304 SS and aluminum(some alloy, not sure which). This unit is located just upstream of my final, ultra clean process-- room temp. I am trying to prevent particles(only) from contaminating it. I understand aluminum forms a hydroxide on the surface and actually gains weight in the presence of Deionized water. I read one paper indicating this. It does not sound like a bad choice since it should not be shedding. I would like to know if there is OTHER evidence someone has to back this up and / or that it is OK for my described use.

Secondly, I have the same basic question about 304 stainless. Thanks!

Brian Schreiber
mech engineer electronics processing development - Maplewood, MN, USA
January 9, 2009

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304 Stainless Steel is fine to use with DI water, particularly if it is passivated. Aluminum is not used, in general, for contact with DI water. While aluminum has been used with distilled water in some cases, it is likely to corrode slowly and to add particles to the water.

Lyle Kirman
consultant - Cleveland Heights, Ohio
January 14, 2009

For electronic grade DI, I would use teflon tubing. Inside a trough or pipe if required.

James Watts
- Navarre, Florida
January 14, 2009