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<p class="MsoNormal">Dear Colleagues,<o:p></o:p></p>
<p class="MsoNormal">Despite a high level of user activity, we have identified several process gas cylinders in our facility that are 10 years old or older and still contain a significant amount of gas. We are evaluating whether our current practices remain
appropriate from both a process reliability and safety standpoint.<o:p></o:p></p>
<p class="MsoNormal">I would appreciate learning how your facilities approach this issue, specifically:<o:p></o:p></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoNormal" style="mso-list:l2 level1 lfo2">Whether you have established age limits for gas cylinders, regardless of remaining contents<o:p></o:p></li><li class="MsoNormal" style="mso-list:l2 level1 lfo2">Any safety or process considerations that drive those limits<o:p></o:p></li><li class="MsoNormal" style="mso-list:l2 level1 lfo2">Whether cylinder change‑outs are handled in‑house or by specialized contractors<o:p></o:p></li></ul>
<p class="MsoNormal">Most of the gases of interest at our facility are:<o:p></o:p></p>
<ul style="margin-top:0in" type="disc">
<li class="MsoNormal" style="mso-list:l0 level1 lfo3">Hydrogen (H₂)<o:p></o:p></li><li class="MsoNormal" style="mso-list:l0 level1 lfo3">Nitrous Oxide (N₂O)<o:p></o:p></li><li class="MsoNormal" style="mso-list:l0 level1 lfo3">Ammonia (NH₃), Silane (SiH₄), SiH₄:He (5:95)<o:p></o:p></li><li class="MsoNormal" style="mso-list:l0 level1 lfo3">Hydrogen Bromide (HBr)<o:p></o:p></li><li class="MsoNormal" style="mso-list:l0 level1 lfo3">Methane (CH₄), Chlorine (Cl₂)<o:p></o:p></li><li class="MsoNormal" style="mso-list:l0 level1 lfo3">Dichlorosilane (SiH₂Cl₂)<o:p></o:p></li><li class="MsoNormal" style="mso-list:l0 level1 lfo3">Boron Trichloride (BCl<sub>3</sub>)<o:p></o:p></li><li class="MsoNormal" style="mso-list:l0 level1 lfo3">Silicon Tetrachloride (SiCl<sub>4</sub>)<o:p></o:p></li></ul>
<p class="MsoNormal">Your insights or references to existing policies would be very helpful as we determine next steps. You may also respond directly to me (aamer@uchicago.edu) if you prefer.<o:p></o:p></p>
<p class="MsoNormal">Thank you in advance for sharing your experience.<o:p></o:p></p>
<p class="MsoNormal">Best regards,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">--<o:p></o:p></p>
<p class="MsoNormal">Aamer Mahmood<o:p></o:p></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">Executive Director<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">Pritzker Nanofabrication Facility<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">William Eckhardt Research Center<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">University of Chicago<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">5640 S. Ellis Ave., Chicago, IL 60637<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">Tel: +1 (773) 702 8903<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt">Web: <a href="pnf.uchicago.edu">
pnf.uchicago.edu</a><o:p></o:p></span></b></p>
<p class="MsoNormal"><o:p> </o:p></p>
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