<div dir="ltr"><div class="gmail_default" style="font-family:arial,sans-serif">Rich,</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">good morning. Here at the University of Michigan/LNF, we have about 250-300' of assorted LN2 piping systems delivering LN2 at 50PSI to various phase separators that are serving MBE tools, and gravity fill stations. All of our piping, except for about 75', is actively pumped through the vacuum pumps that support each of the five LN2 phase separators. Typically, when we have an issue with the piping (frosting over on the atmosphere jacket) it's because one of the users violated the vacuum integrity of the jacket at their tool connection. In those instances, we'll isolate the section of the system and allow it to warm up while under vacuum. That usually fixes the issue. On occasion, we have had to shut down the entire delivery system and allow it to warm up to fix the thermal violation. We have not noticed any issues with the static vacuum lines, and they've been installed since 1987.</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">I will say that our delivery system is designed so that by manipulating vacuum valves, we can "select" which vacuum pump is "pulling" on the annular space of the vacuum jacket. It wasn't always like this. We made some changes once we had more than two MBE tools (PI's) on the delivery system. </div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,sans-serif">If you have any additional questions, just give me a call.</div><div class="gmail_default" style="font-family:arial,sans-serif"><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div>Dennis<span class="gmail_default" style="font-family:arial,sans-serif"> schweiger</span></div><div><span class="gmail_default" style="font-family:arial,sans-serif">University of Michigan/LNF</span></div><div><span class="gmail_default" style="font-family:arial,sans-serif">Facilities Manager</span></div><div> </div><div>734.647.2055 Ofc</div></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Feb 16, 2021 at 7:48 PM Harlan, Richard D <<a href="mailto:rharlan@purdue.edu">rharlan@purdue.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">
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<p class="MsoNormal">Greetings All,<u></u><u></u></p>
<p class="MsoNormal">Our facility is now 15 years old and starting to require more preventative maintenance. The vacuum jacketed liquid nitrogen line was showing an increased leak rate for a short period of time. It has since stabilized, but has raised questions
about potential leaks in the system. <u></u><u></u></p>
<p class="MsoNormal">Have any of your facilities experienced this type of problem and what PM’s have you put in place to address the LN2 and vacuum jacketed line integrity?<u></u><u></u></p>
<p class="MsoNormal">Thank you in advance for the feedback.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks,<u></u><u></u></p>
<p class="MsoNormal">Rich Harlan<u></u><u></u></p>
<p class="MsoNormal">Research Engineering<u></u><u></u></p>
<p class="MsoNormal">Birck Nanotechnology Center | Room 2287C<u></u><u></u></p>
<p class="MsoNormal"><b>Office:</b> <span style="color:rgb(46,116,181)">765.494.6697</span> |
<b>Email:</b> <a href="mailto:rharlan@purdue.edu" target="_blank"><span style="color:rgb(5,99,193)">rharlan@purdue.edu</span></a><u></u><u></u></p>
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