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</style><article id="node-931007" class="node node-logentry contextual-links-region article ia-n clearfix" role="article"><header class="node-header"><h1 class="node-title">
<a href="https://logbooks.jlab.org/entry/3858017" rel="bookmark">Follow-up Re: Hall B 80K warm up</a>
</h1>
</header><div class="contextual-links-wrapper"><ul class="contextual-links"><li><a href="https://logbooks.jlab.org/entry/3858017/edit?destination=email/send">Edit</a></li><li><a href="https://logbooks.jlab.org/entry/3858017/delete?destination=email/send">Delete</a></li></ul></div>
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<p class="author-datetime">
Lognumber <a href="https://logbooks.jlab.org/entry/3858017" class="lognumber" data-lognumber="3858017">3858017</a>. Submitted by <a href="https://logbooks.jlab.org/user/kashy">kashy</a> on <time datetime="2020-11-19T07:04:29-0500" pubdate="pubdate"><a href="https://logbooks.jlab.org/entries?start_date=1605783869&end_date=1605791069&book=HBSOLENOID&book=HBTORUS&book=CLOG">Thu, 11/19/2020 - 07:04</a></time>. </p>
<table class="field-vitals"><tr><th>Logbooks: </th><td><a href="https://logbooks.jlab.org/book/hbsolenoid">HBSOLENOID</a> <a href="https://logbooks.jlab.org/book/hbtorus">HBTORUS</a> <a href="https://logbooks.jlab.org/book/clog">CLOG</a></td></tr><tr><th>References: </th><td><a href="https://logbooks.jlab.org/entry/3857580">3857580 - Hall B 80K warm up</a></td></tr></table></div>
<div class="logentry node-content">
<p>Yesterday I increased the max flow to Hall B to 5g/s of clean helium from ESR (and back to the purifiers) that is being cooled to 80K inside the DBX</p>
<p>The Torus is now at 87K and rising at 0.01K/hr<br />
The Solenoid is now at 77K and rising at 0.08K/hr<br />
The Dewar is flowing just a trickle with the inlet temperature at 129K and outlet at 281K but it is enough to keep the return valve controlling averaging 20% open while regulating the pressure at 1.4atm.</p>
<p>Prior to recooling to 4K the Dewar flow will be increased to bring it back down below 100K</p>
<p>The dewar vacuum space and its U-tubes need pumping.<br />
The O-Rings on the Dewar pump out valve should be changed out since it is warm (back fill with GN2 of course). These have not been changed in at least 23 years (since I started in hall B<br />
If we don't have spares, contact: <a href="https://www.cryofab.com/">https://www.cryofab.com/</a></p>
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