<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">No biocide or corrosion inhibitors on
the pcw loop.<br>
Piping is copper. 306 SS was rejected for cost savings. <br>
CPVC would have been preferred and additional cost <br>
savings but initial code interpretation would not allow CPVC <br>
since it does not meet 25/50 smoke/flame spread requirement.<br>
<br>
Resistivity target is 200kohm.<br>
At 175k, tank dumps ~20% system volume and is refilled with RO.<br>
Resistivity recovers to ~275k. System resistivity gradually
decreases<br>
over 3-5 days and cycle repeats. Recurring fresh water input is
what<br>
avoids need for biocide or inhibitor. <br>
<br>
If any failure of pcw pump/flow - system automatically crosses
over<br>
to single pass ICW. Resistivity spec is bypassed. When PCW flow<br>
is restored, resistivity control is reimplemented and 4-5 tank
dumps<br>
required to restore system to normal. A picture is worth 1000
words:<br>
Appended graph summarizes resistivity as function of time for the
<br>
past 1month. 2 cross over events to ICW are noted. <br>
<br>
Bill Flounders<br>
UC Berkeley<br>
<br>
<br>
<img src="cid:part1.03060004.05050008@eecs.berkeley.edu"
width="466px" border="0" height="270px"><br>
<br>
<br>
<br>
Miller, Timothy J wrote:<br>
</div>
<blockquote
cite="mid:7E4F526EF5F18B4BA90905AC52DF05F179B84EE4@WPVEXCMBX08.purdue.lcl"
type="cite">
<pre wrap="">Iain,
Normally Jeff Kuhn would answer this, but he is out this week on family business.
All of the components in our PCW system are stainless steel, CPVC, or fiberglass. We haven't really worried about corrosion preventers since the building was commissioned.
In ten years of operation we have had one problem with bacteria. The system was dosed once with biocide, which was then removed by dilution.
No UV sterilizers or mixed beds. If there is a catastrophic loss of water we can refill from the RO on the UPW system, which runs 1-2 MegOhmcm. If the resistivity of the water drops below .95 Meg the system is topped off with concentrate water from the ultrafilters on the UPW system (18.2 Meg) with the excess water overflowing to drain until the resistivity returns to 1.05 Meg. Very simple and very inexpensive.
Tim
Timothy J. Miller
Purdue University
Birck Nanotechnology Center
1205 West State Street
West Lafayette, IN 47907-2057
765-427-4712
-----Original Message-----
From: <a class="moz-txt-link-abbreviated" href="mailto:labnetwork-bounces@mtl.mit.edu">labnetwork-bounces@mtl.mit.edu</a> [<a class="moz-txt-link-freetext" href="mailto:labnetwork-bounces@mtl.mit.edu">mailto:labnetwork-bounces@mtl.mit.edu</a>] On Behalf Of Anteney I.M.
Sent: Tuesday, September 15, 2015 2:16 AM
To: Dennis Schweiger
Cc: Vito Logiudice; <a class="moz-txt-link-abbreviated" href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>
Subject: Re: [labnetwork] Temperature specification for facility process chilled water
Denis,
I'm particularly interested in your comment about polishing the loops to get 1 mega-ohm resistance as we have struggled to do this especially when we dose the system with biocide and corrosion inhibitors. What are you using to polish the system, what inhibitors/biocides do you use and how do these affect the conductivity.
Regards
Iain
Cleanroom Manager
University of Southampton
Sent from my iPhone
On 15 Sep 2015, at 00:36, Dennis Schweiger <<a class="moz-txt-link-abbreviated" href="mailto:schweig@umich.edu">schweig@umich.edu</a><a class="moz-txt-link-rfc2396E" href="mailto:schweig@umich.edu"><mailto:schweig@umich.edu></a>> wrote:
Vito,
here at UofMichigan, one of our PCW systems runs about 62.5F (16.9C) with a daily deviation of about 1F. The second runs about 59-60F (15C). It too has a daily deviation of about 1F. For both systems we may see a seasonal deviation of 3-4F as the main chiller plant transitions from "free cooling" to the use of chillers to create cooling water for the campus wide loop. We also "polish" both loops to 1 meg-ohm so that we have a "high resistance" in the RF cooling circuits.
Dennis Schweiger
University of Mighigan/LNF
734.647.2055 Ofc
On Fri, Sep 11, 2015 at 3:47 PM, Vito Logiudice <<a class="moz-txt-link-abbreviated" href="mailto:vito.logiudice@uwaterloo.ca">vito.logiudice@uwaterloo.ca</a><a class="moz-txt-link-rfc2396E" href="mailto:vito.logiudice@uwaterloo.ca"><mailto:vito.logiudice@uwaterloo.ca></a>> wrote:
Dear Colleagues,
The process chilled water loop in our cleanroom has consistently oscillated between ~15.4C and ~17.2C over a span of roughly 10 minutes. Our Plant Operations group is looking into the possibility of tightening this up for us by tuning the control sequence. They have asked for guidance on an acceptable specification.
In light of this I would appreciate hearing from you as to your facility's PCW temperature target and tolerance. Thank you much.
Best regards,
Vito
--
Vito Logiudice P.Eng.
Director of Operations, Quantum NanoFab
University of Waterloo
Lazaridis QNC 1207
200 University Avenue West
Waterloo, ON Canada N2L 3G1
Tel.: (519) 888-4567 ext. 38703<a class="moz-txt-link-rfc2396E" href="tel:%28519%29%20888-4567%20%C2%A0ext.%2038703"><tel:%28519%29%20888-4567%20%C2%A0ext.%2038703></a>
Email: <a class="moz-txt-link-abbreviated" href="mailto:vito.logiudice@uwaterloo.ca">vito.logiudice@uwaterloo.ca</a><a class="moz-txt-link-rfc2396E" href="mailto:vito.logiudice@uwaterloo.ca"><mailto:vito.logiudice@uwaterloo.ca></a>
Website: <a class="moz-txt-link-freetext" href="https://fab.qnc.uwaterloo.ca">https://fab.qnc.uwaterloo.ca</a>
_______________________________________________
labnetwork mailing list
<a class="moz-txt-link-abbreviated" href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a><a class="moz-txt-link-rfc2396E" href="mailto:labnetwork@mtl.mit.edu"><mailto:labnetwork@mtl.mit.edu></a>
<a class="moz-txt-link-freetext" href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</a>
_______________________________________________
labnetwork mailing list
<a class="moz-txt-link-abbreviated" href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a><a class="moz-txt-link-rfc2396E" href="mailto:labnetwork@mtl.mit.edu"><mailto:labnetwork@mtl.mit.edu></a>
<a class="moz-txt-link-freetext" href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</a>
_______________________________________________
labnetwork mailing list
<a class="moz-txt-link-abbreviated" href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>
<a class="moz-txt-link-freetext" href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</a>
_______________________________________________
labnetwork mailing list
<a class="moz-txt-link-abbreviated" href="mailto:labnetwork@mtl.mit.edu">labnetwork@mtl.mit.edu</a>
<a class="moz-txt-link-freetext" href="https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork">https://www-mtl.mit.edu/mailman/listinfo.cgi/labnetwork</a>
</pre>
</blockquote>
<br>
</body>
</html>