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DI water quality lost over long distances?

September 10, 2008

Finishing.com experts,

I've been scouring this site for an answer to a question for hours and other than coming up dry, I've realized that I've definitely come to the right place. Briefly, I'm a manufacturing engineer at a medical parts manufacturer (layman at finishing) and I'm currently in the process of helping to lay out the placement of a DI water system for a RAMCO brand parts cleaner. I've been told that the distance of the DI delivery system needs to be in close proximity of the RAMCO parts cleaner. (Approximately 3 feet) This is the statement my question stems from:

"...The distance of DI water must be as short as possible to the delivery port otherwise the water quality (in Meg ohms) drops. For this reason the DI columns should be positioned close to the Ramco wash system to provide the shortest delivery path as possible. DI water cannot be plumbed in a hose from the wall over to the new Ramco without losing its high quality status. In short, the DI columns should be positioned near the Ramco system..."

My question is; is it possible that, with the proper plumbing, the DI water loses its "quality status" over a certain distance?

If so, what distance is acceptable before quality is lost?

Thank you in advance for helping me in my hour of need.

Louis Dertouzos
Manufacturing Engineer - Naples, Florida, USA

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September 12, 2008

I do not buy that statement IF you are using the proper piping. For 18 MegOhm water you definitely need teflon tubing.
For say 10 MegOhm water, poly propylene would work fine. PVC is a bit of a problem because of the glue joints where solvent will leach out for a long time. Welded or threaded PVC should not have a problem after the first couple of days where traces of materials will leach out.
If you are using stainless pipe or valves, then the statement is definitely true.

James Watts
- Navarre, Florida