From: Kuhn, Jeffrey G
Sent: Tuesday, June 30, 2015 2:55 PM
To: BNC Staff
Subject: Second Notification - Low Temperature Chiller Repair
All,
The needed chiller repairs that were communicated last week are now scheduled for Tuesday 7/7/15 through Thursday 7/9/15. As stated earlier, we will not have proper humidity control in the laboratories, cleanroom, or biocleanroom while the chiller is down.
Additionally, the testing done this morning is complete. For the test, we shut off the low temperature chilled water to the cleanroom makeup air handlers in order to simulate the chiller being down. Based on the test, we can expect humidity in the cleanroom and biocleanroom to reach as high as 55% - 60% (the normal range is 40% to 50%). Humidity in the laboratories, normally around 40%, could also climb as high as 55% - 60%.
There are several important items to note:
* The weather forecast for Tuesday through Thursday next week calls for conditions approximately the same as today. If that forecast holds true, then the humidity excursions presented above would be pretty much on target. However, as we all know, weather forecasts that far in the future aren't always accurate. Therefore you should plan for conditions worse than predicted, especially if it is hotter and muggier than it is today.
* While our in-house chiller is being repaired, campus chilled water from the Wade power plant will be doing all of the cooling and dehumidification for the entire building. If Wade were to have chilled water issues while our in-house unit is down and incoming water temperature were to rise, then humidity values could go higher than predicted and we may lose temperature control as well.
o We will be contacting the management at Wade to inform them of our upcoming chiller repair, and to make sure they do due diligence to keep the campus chilled water flowing into Birck at the proper temperature.
* During the downtime, Mark Voorhis and I will be keeping a close eye on dewpoint values in order to ensure there is no condensation that could damage equipment. If we were to approach the calculated dewpoint, then we would raise the temperature set point in order to stay above the dewpoint value, thereby preventing condensation.
I will send out a final notice on Monday 7/6/15. Thank you in advance for your patience and understanding.
Regards,
Jeff Kuhn
Facility Engineer
Birck Nanotechnology Center
Purdue University
1205 W. State St.
West Lafayette, IN 47907
Ph: (765) 496-8329
Fax: (765) 496-2018
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All,
A recent lab analysis indicates critically low oil viscosity in one of the circuits of our Carrier low temperature chiller. That chiller is used to maintain humidity setpoints during warm weather.
In order to prevent a catastrophic and expensive failure of the chiller's compressors, we must schedule the unit to be down for repair as soon as possible. The repairs will take approximately three (3) days to complete. During that time, we will be unable to properly control humidity in the cleanroom, biocleanroom, and laboratories. It is impossible to predict the severity of the humidity excursion since it will be largely weather dependent. The warmer and more humid the outside air, the more severe the deviation from setpoint will be.
We have not yet scheduled the repairs pending feedback from Birck users who will be impacted. If you have any input regarding the timing of the repairs, please let me know as soon as possible since it is vital that we get the repairs underway. I will wait for feedback until Monday 6/29 before scheduling repairs with the contractor. Once I know the dates of the downtime, I will communicate them to you.
Please pass this information along to anyone not on this distribution who needs to be aware, and please contact me with your feedback or questions by next Monday.
