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July 1998

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Subject:
From:
Andy Magee <[log in to unmask]>
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Date:
Mon, 20 Jul 1998 22:36:26 -0400
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Bill, and Ed

Be very careful trying to use pH as a judge of your DI water. It's
nearly impossible to measure a sample without picking up CO2 from the
air and changing the pH. The higher the resistivity the faster the
change.

Andy Magee
Flex Guru
[log in to unmask]

Ed wrote,

         Mon, 20 Jul 1998 11:28:05 -0500
   From:
         [log in to unmask]

Bill,

Typically, as D.I. beds begin to fail (exhaust) either the cation or
anion
(as a function of your H2O constituents) exhausts first which causes a
pH
imbalance.  This occurs increasingly below approx 500K, so 1M builds in
a
margin of safety that the water quality will be within reasonable
boundaries.

If you want to confirm this, simply measure the pH (inexpensive pocket
meters are available from Fischer Scientific) as yor beds fall below 1M
and
plot the curve pH vs. resistivity.

Hope this helps!

Regards,



Ed Popielarski
QTA Machine
10 Mc Laren, Suite D
Irvine, Ca. USA 92618
Ph: (949)581-6601
Fx: (949)581-2448
E-Mail: [log in to unmask]

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