[labnetwork] Shared Chiller [for equipment cooling] Issues
Bob Hamilton
roberthamilton at berkeley.edu
Tue Sep 23 10:33:56 EDT 2014
Kamal,
The Microlab, which preceded the Marvell NanoLab, had issues with big
dips in city water pressure when classes let out. Our building was also
a teaching building and on the hour, when classes ended and restrooms
were heavily used, we'd see large dips in pressure that resulted in our
reverse osmosis water system shutting down from low pressure. We also
had a problem with inertia. On start-up, the RO pump dipped the inlet
pressure because of the inertia of the water column.
We solved the problem by tee'ing in a 100 gallon expansion tank
(sometimes called a draw-down tank). This required adding a check valve
to prevent the tank from back-feeding the building. This tank was
equipped with an air bladder pressurized to 80 psi which was the motive
force to keep water under pressure. It worked flawlessly. These tanks
are often used in association with well pumps so pumps do not end up
close-cycling. A switch with a dead band of ~ 20-30 psi is then used to
cycle the pump.
Having shared this, it does not seem applicable to your chiller issue.
There are devices with smaller volumes called pulsation dampers which
mitigate the high frequency pulses from gear pumps. Perhaps that is what
someone has recommended?
Bob
On 9/22/2014 10:32 PM, Kamal Yadav wrote:
> Dear All,
>
> Thank you very much for sharing your experiences.
>
> There is a design where one puts an expansion tank on the return line
> for these shared chiller, probably to avoid ripples, flow shocks, that
> one gets when another tool is being switched ON or OFF. I found a
> document which is attached which talks about designing such cooling
> water circuits. This water is only for process equipment cooling, and
> not facilities equipment cooling.
>
> If anybody has worked without these expansion tanks, and if using flow
> settlers is enough that would be great to know, we may need to modify
> our circuits little bit, if needed.
>
> Thanks,
> Kamal.
>
>
>
>
> On Mon, Sep 22, 2014 at 8:37 PM, Bob Hamilton
> <roberthamilton at berkeley.edu <mailto:roberthamilton at berkeley.edu>> wrote:
>
> Kamal Yadav,
>
> It is difficult to diagnose your issue given the information in
> your e-mail. It is possible a single tool is using more water than
> it needs and therefore reducing the available volume to tools with
> higher impedance cooling circuits. You may also have a blocked
> cooling channel in a tool(s). Consider running water through them,
> backwards and into an open drain or bucket to back-flush them.
>
> A question; what purpose does this chiller serve? Does it supply
> deionized for rf cooling circuits where the resistivity of the
> water is important or does it simply provide equipment cooling? Is
> it a heat exchanger (HX) or is it Freon-based centrifigal chiller?
> Do you have a rotameter in the cooling loop?
>
> Assuming the conductance of various tools allows most of the
> process cooling water to flow through those tools with lowest
> impedance consider adding "flow-setters" to your tools or just to
> the tool using too much water. There are dynamic version of
> flow-setters that adjust flow to a specific volume of
> liters-per-minute and maintain this constant flow over a range of
> pressure.
>
> At the Marvell NanoLab we've used flow-setters made of brass, PVC
> and stainless depending on the application. If you choose PVC
> versions, I'd pick male pipe thread (mpt) over female pipe thread
> (fpt). We try and avoid threading metal mpt fittings into plastic
> fpt fittings because the plastic fitting may crack at some part of
> its service life causing flooding.
>
> Appended are a few US links that provide an example of the device
> I am referring to. I've also seen them on EBAY.
> http://www.deanbennett.com/dole-flow-control-valves.htm
> http://www.haysfluidcontrols.ca/hays_automatic_flow_controls_2305.htm
> http://www.merrillmfg.com/product/08-WellPoints/Merrill-Valves/features.php
> http://www.plastomatic.com/fc.html
> http://www.swtwater.com/catalog/1318_flow_controls.htm
>
> Regards from the MNL,
> Bob Hamilton
>
> --
> Robert Hamilton
> University of California at Berkeley
> Marvell NanoLab
> Equipment Eng. Mgr.
> Room 520 Sutardja Dai Hall
> Berkeley, CA 94720-1754
> bob at eecs.berkeley.edu <mailto:bob at eecs.berkeley.edu>
> e-mail preferred
> My personal mobile:510-325-7557 <tel:510-325-7557>
>
>
> On 9/21/2014 11:22 PM, Kamal Yadav wrote:
>> Dear All,
>>
>> We are facing chiller [for cooling water for equipment] issues,
>> most likely flow issues, probably due to using same chiller for
>> multiple equipment. Though chiller total cooling capacity is able
>> to provide flow/pressure but in an shared equipment scenario,
>> could there be issues. Suddenly some equipment, in use, trips,
>> because of low flow of cooling water probably.
>>
>> Did anybody faced these issues, are we diagnosing it correctly?
>>
>> Thanks a lot.
>>
>> --
>> Thanks,
>> Kamal Yadav
>> Sr. Process Technologist
>> IITBNF, EE Department, Annexe,
>> IIT Bombay, Powai
>> Mumbai 400076
>> Internal: 4435
>> Cell: 7506144798
>> Email: kamal.yadav at gmail.com <mailto:kamal.yadav at gmail.com>,
>> kamalyadav at ee.iitb.ac.in <mailto:kamalyadav at ee.iitb.ac.in>
>>
>>
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>
> --
> Robert Hamilton
> University of California at Berkeley
> Marvell NanoLab
> Equipment Eng. Mgr.
> Room 520 Sutardja Dai Hall
> Berkeley, CA 94720-1754
> bob at eecs.berkeley.edu <mailto:bob at eecs.berkeley.edu>
> Phone:510-809-8600 <tel:510-809-8600>
> Mobile:510-325-7557 <tel:510-325-7557> (Emergencies only poor cell phone service in lab)e-mail preferred
>
>
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>
>
>
> --
> Thanks,
> Kamal Yadav
> Sr. Process Technologist
> IITBNF, EE Department, Annexe,
> IIT Bombay, Powai
> Mumbai 400076
> Internal: 4435
> Cell: 7506144798
> Email: kamal.yadav at gmail.com <mailto:kamal.yadav at gmail.com>,
> kamalyadav at ee.iitb.ac.in <mailto:kamalyadav at ee.iitb.ac.in>
--
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Equipment Eng. Mgr.
Room 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
bob at eecs.berkeley.edu
Phone: 510-809-8600
Mobile: 510-325-7557 (Emergencies only poor cell phone service in lab)e-mail preferred
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