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Kamal,<br>
<br>
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. <br>
<br>
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.<br>
<br>
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?<br>
<br>
Bob <br>
<br>
<div class="moz-cite-prefix">On 9/22/2014 10:32 PM, Kamal Yadav
wrote:<br>
</div>
<blockquote
cite="mid:CAOfoCyi-0Rz18=BKGCvWokSeygb+J6QJG4JaD707aYJ=UL9QZw@mail.gmail.com"
type="cite">
<meta http-equiv="Context-Type" content="text/html; charset=UTF-8">
<div dir="ltr">Dear All,
<div><br>
</div>
<div>Thank you very much for sharing your experiences.</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Kamal.</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Sep 22, 2014 at 8:37 PM, Bob
Hamilton <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:roberthamilton@berkeley.edu" target="_blank">roberthamilton@berkeley.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote">
<div> Kamal Yadav,<br>
<br>
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. <br>
<br>
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?<br>
<br>
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. <br>
<br>
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. <br>
<br>
Appended are a few US links that provide an example of the
device I am referring to. I've also seen them on EBAY. <br>
<a moz-do-not-send="true"
href="http://www.deanbennett.com/dole-flow-control-valves.htm"
target="_blank">http://www.deanbennett.com/dole-flow-control-valves.htm</a><br>
<a moz-do-not-send="true"
href="http://www.haysfluidcontrols.ca/hays_automatic_flow_controls_2305.htm"
target="_blank">http://www.haysfluidcontrols.ca/hays_automatic_flow_controls_2305.htm</a><br>
<a moz-do-not-send="true"
href="http://www.merrillmfg.com/product/08-WellPoints/Merrill-Valves/features.php"
target="_blank">http://www.merrillmfg.com/product/08-WellPoints/Merrill-Valves/features.php</a><br>
<a moz-do-not-send="true"
href="http://www.plastomatic.com/fc.html"
target="_blank">http://www.plastomatic.com/fc.html</a><br>
<a moz-do-not-send="true"
href="http://www.swtwater.com/catalog/1318_flow_controls.htm"
target="_blank">http://www.swtwater.com/catalog/1318_flow_controls.htm</a><br>
<br>
Regards from the MNL,<br>
Bob Hamilton<br>
<br>
<pre cols="72">--
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Equipment Eng. Mgr.
Room 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
<a moz-do-not-send="true" href="mailto:bob@eecs.berkeley.edu" target="_blank">bob@eecs.berkeley.edu</a>
e-mail preferred
My personal mobile: <a moz-do-not-send="true" href="tel:510-325-7557" value="+15103257557" target="_blank">510-325-7557</a>
</pre>
<span class=""> <br>
<div>On 9/21/2014 11:22 PM, Kamal Yadav wrote:<br>
</div>
</span>
<blockquote type="cite">
<div>
<div class="h5">
<div dir="ltr">Dear All,
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>Did anybody faced these issues, are we
diagnosing it correctly?</div>
<div><br>
</div>
<div>Thanks a lot.<br>
<div><br>
</div>
-- <br>
<div dir="ltr">
<div>Thanks,<br>
</div>
<div>Kamal Yadav</div>
<div>Sr. Process Technologist<br>
</div>
<div>IITBNF, EE Department, Annexe,</div>
<div>IIT Bombay, Powai</div>
<div>Mumbai 400076</div>
<div>Internal: 4435</div>
<div>Cell: 7506144798</div>
<div>Email: <a moz-do-not-send="true"
href="mailto:kamal.yadav@gmail.com"
target="_blank">kamal.yadav@gmail.com</a>,
<a moz-do-not-send="true"
href="mailto:kamalyadav@ee.iitb.ac.in"
target="_blank">kamalyadav@ee.iitb.ac.in</a></div>
</div>
</div>
</div>
<br>
<fieldset></fieldset>
<br>
</div>
</div>
<span class="">
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</pre>
</span></blockquote>
<span class="HOEnZb"> <br>
<pre cols="72">--
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Equipment Eng. Mgr.
Room 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
<a moz-do-not-send="true" href="mailto:bob@eecs.berkeley.edu" target="_blank">bob@eecs.berkeley.edu</a>
Phone: <a moz-do-not-send="true" href="tel:510-809-8600" value="+15108098600" target="_blank">510-809-8600</a>
Mobile: <a moz-do-not-send="true" href="tel:510-325-7557" value="+15103257557" target="_blank">510-325-7557</a> (Emergencies only poor cell phone service in lab)e-mail preferred
</pre>
</span></div>
<br>
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<br>
</blockquote>
</div>
<br>
<br>
<div><br>
</div>
-- <br>
<div dir="ltr">
<div>Thanks,<br>
</div>
<div>Kamal Yadav</div>
<div>Sr. Process Technologist<br>
</div>
<div>IITBNF, EE Department, Annexe,</div>
<div>IIT Bombay, Powai</div>
<div>Mumbai 400076</div>
<div>Internal: 4435</div>
<div>Cell: 7506144798</div>
<div>Email: <a moz-do-not-send="true"
href="mailto:kamal.yadav@gmail.com" target="_blank">kamal.yadav@gmail.com</a>,
<a moz-do-not-send="true"
href="mailto:kamalyadav@ee.iitb.ac.in" target="_blank">kamalyadav@ee.iitb.ac.in</a></div>
</div>
</div>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Robert Hamilton
University of California at Berkeley
Marvell NanoLab
Equipment Eng. Mgr.
Room 520 Sutardja Dai Hall
Berkeley, CA 94720-1754
<a class="moz-txt-link-abbreviated" href="mailto:bob@eecs.berkeley.edu">bob@eecs.berkeley.edu</a>
Phone: 510-809-8600
Mobile: 510-325-7557 (Emergencies only poor cell phone service in lab)e-mail preferred
</pre>
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