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December 1999

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Subject:
From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 14 Dec 1999 18:33:56 +0100
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Graham

There is distilled water and distilled water. It depends on the installation used. Even
triple-distilled in quartz water will not have as low a conductivity as a good DI
water, but may have lower impurities of other natures, especially particulate matter.
However, single distilled water from an iron still would be definitely suspect.

Unless it has been distilled more than once or in a reflux still, then a number of
impurities can be carried over. A steam bubble bursting at the surface will throw up
microdroplets of contaminated water into the steam. A single distillation of sea water,
for example, with 35 000 ppm dissolved solids will produce a water of about 1 000 ppm
in a non-reflux still. Multistage solar flash distillation of sea water always is done
over three stages to produce potable water (c. 500 ppm NaCl max, typically 100 uS-cm).
True RO + DI water is the most economic reasonably pure water.

If you buy distilled water, get a written certification of a conductivity of less than
1 uS-cm at the time of packing (it may rise to about 5 if not consumed rapidly).

Brian

Collins, Graham wrote:

> Good day Technetters!
>
> A water / chemistry question for the TechNet today.  Is distilled water an
> acceptable substitute for DI water?  My non-chemistry mind thinks so but I'd
> like a more qualified opinion.
>
> Why?  We are looking to up our cleaning capacity, and while the DI set-up we
> have would keep up with the running requirements of a bigger cleaner, it
> would have a hard time filling the tank for start-up.  So I can either buy a
> bigger DI set-up, or buy DI water as required.  Our local filtering supplier
> claims distilled will do, but I question his expertise.  Is he correct?
>
> As always - thanks, and have a Cool Yule!
>
> Graham Collins
> Process Engineer,
> Litton Systems Canada, Atlantic Facility
> (902) 873-2000 ext 6215
>
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--
Brian Ellis
Protonique SA
PO Box 78
CH-1032 Romanel-sur-Lausanne, Switzerland
Voice: +41 21-648 23 34 Fax: +41 21-648 24 11
E-mail: [log in to unmask]
URL: Technical and consultancy divisions:
       http://www.protonique.com
     Web services division:
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