[labnetwork] Temperature specification for facility process chilled water

[Peter J Duda III]

Vito et al

In all of the great discussion regarding temperature and treatment of PCW in various facilities, I feel obligated to mention one item:  Please be aware of your entire design and operating environment when considering temperature setpoints, especially when it comes to any kind of chilled water.  For instance: One response to this thread mentioned they are controlling their PCW to 59 +/- 2F which means you will have 57F water some of the time.  That temperature could very well cause condensation if it were implemented in a location where the individual wasn't aware of their design environment and that environment couldn't support such a temperature.   PCW often runs in and out of "building" conditioned space with looser tolerances than the cleanroom space.  If you are running non-insulated copper and have a higher PCW design temperature that you just lowered - you could have a large problem that could do significant damage before it was discovered (think about spaces above cleanroom ceilings, etc).  As well, depending on whether or not your facility has a 1% or even .1% ASHRAE design temperature - you may not have seen the highest dew point in your room yet.  A cleanroom that is within temperature spec could easily hit a 57F dew point with only a small drift in humidity due to an extremely hot and humid day.  In my experience, I have never needed facility PCW to be colder than 18C, and even if it were required in some instances - I would likely utilize a separate chiller rather than risk problems with condensation.

Thanks
Peter J Duda
Technical Manager, Pritzker Nanofabrication Facility
Institute for Molecular Engineering
University of Chicago
5555 South Ellis Avenue
Young 006D
Chicago, IL  60637
Office: 773-702-8903
Cell:  805-636-2323
duda at uchicago.edu
ime.uchicago.edu

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Vito Logiudice
Sent: Friday, September 11, 2015 2:47 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] Temperature specification for facility process chilled water

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
Email: vito.logiudice at uwaterloo.ca<mailto:vito.logiudice at uwaterloo.ca>
Website: https://fab.qnc.uwaterloo.ca

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