<div dir="ltr"><p>Dear Kyle,</p><p>Thank you for raising this — it’s a very relevant point from a safety and design perspective.</p>
<p>In most wet bench designs, theEMO is intended primarily to address <strong>immediate personnel safety risks</strong> by isolating active energy sources. Accordingly, EMOs typically shut down high voltage, heaters, pumps, and wafer handling systems.</p>
<p>However, utilities such as DI water, N₂, and CDA are generally <strong>not interlocked with the EMO</strong>, as they often play a role in maintaining a safe state of the system. For example, DI water supports dilution and cooling, while N₂ and CDA are used for purging and pneumatic valve actuation. Interrupting these during an emergency could, in some cases, lead to unintended risks such as accumulation of hazardous vapors or loss of temperature control.</p>
<p>That said, incidents such as DI water leaks are usually addressed through <strong>independent safety layers</strong>, such as leak detection systems and interlocked shutoff valves with FOM relay, rather than through the EMO itself. This allows for targeted isolation of the affected utility without impacting other safety-critical functions.</p>
<p>Given your recent experience, it may be worthwhile to evaluate the implementation of <strong>leak detection and localized DI shutoff mechanisms</strong>, supported by a risk assessment, instead of modifying the EMO functionality directly.</p>
<p><br></p>
<p>Best regards,<br>
Shruti Hegde</p></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Wed, Apr 8, 2026 at 5:17 AM Prashant Srinivasan <<a href="mailto:prashant@ucsb.edu">prashant@ucsb.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
<div>
<p>Kyle,</p>
<p>The EMO on our benches (Ancient Pure Aire) shuts off the 208V and
120 V circuits (fluorescent lamps, Ph meter, outlets and the
laminar flow motor). The DI/CDA/N2 systems are passive (no
electrical actuation). </p>
<p>If you want to go the automated route, a DIY approach is an OpAmp
comparator (with suitable level shifters). COTS solutions are
aplenty, something like this:
<a href="https://www.bapihvac.com/product/water-leak-detector-with-attached-or-remote-sensor/" target="_blank">https://www.bapihvac.com/product/water-leak-detector-with-attached-or-remote-sensor/</a>
(or) <a href="https://www.ato.com/water-leak-sensor-transmitter" target="_blank">https://www.ato.com/water-leak-sensor-transmitter</a></p>
<p>I'd say a monthly visual inspection and replacing lines on the
verge of failing should suffice.</p>
<p>Prashant </p>
<div>On 4/7/2026 9:13 AM, Kyle Keenan wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>Hello All,</div>
<div><br>
</div>
<div>I'm curious to know what the EMO's do on the wet benches in
your facilities. Do they shut down CDA, N2 or water, or just
high voltage? What is the thought process behind what
does/does not get shut down? We recently had a bad DI water
leak on one of our benches, and we were a little surprised to
find out that the EMO did not shut off the water supply, so we
are considering whether or not we want to make a changes to
the way the EMO's work on our benches. </div>
<div><br>
</div>
<div>I look forward to reading your replies.</div>
<div><br>
</div>
<div>Best,</div>
<span class="gmail_signature_prefix">-- </span><br>
<div dir="ltr" class="gmail_signature">
<div dir="ltr">
<div>Kyle Keenan</div>
<div><br>
</div>
<div>Senior Manager - Laboratory Operations<br>
</div>
<div>Quattrone Nanofabrication Facility</div>
<div>University of Pennsylvania</div>
<div>P: 215-898-7560</div>
<div>F: 215-573-4925</div>
<div><br>
</div>
<div><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXe66pb_bj7n0vXky5r9uEf3y5sMz4yFV2HK-lOuGGMzj3VS6ybtG41AGZcUidgjZH61GUaGnR38EWIiqL3J-TsS9TxolLE--_h8K79Lk-dgYMHSjcBvHUy-zL7bWnKmfmJklE7i?key=OpK1PovMbdplDTzml6yQgugX" width="221" height="80" style="margin-left: 0px; margin-top: 0px;"></div>
</div>
</div>
</div>
<br>
<fieldset></fieldset>
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<pre cols="72">--
Prashant Srinivasan,
Teaching Cleanroom Engineer
Electrical & Computer Engineering
University of California, Santa Barbara
Santa Barbara, California 93106
<a href="https://www.ece.ucsb.edu/department-resources/electronics-shop/tcr" target="_blank">https://www.ece.ucsb.edu/department-resources/electronics-shop/tcr</a></pre>
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