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</style><article id="node-616138" class="node node-logentry article ia-n clearfix" role="article"><header class="node-header"><h1 class="node-title">
<a href="https://logbooks.jlab.org/entry/3543260" rel="bookmark">Hall B Cryo Recovery from Power Outage</a>
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<p class="author-datetime">
Lognumber <a href="https://logbooks.jlab.org/entry/3543260" class="lognumber" data-lognumber="3543260">3543260</a>. Submitted by <a href="https://logbooks.jlab.org/user/rmiller">rmiller</a> on <time datetime="2018-03-05T19:46:11-0500" pubdate="pubdate">Mon, 03/05/2018 - 19:46</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>Entry Makers: </th><td>kashy</td></tr></table></div>
<div class="logentry node-content">
<p>13:39 Hall B lost cryo flow from ESR<br />
1500 Both magnets warmed up and lost reservoir level. Magnets were already ramped down for maintenance in the Hall. Buffer dewar relief valves lifted due to high return pressure, one valve did not reseat. Target cryostat relief valve also lifted and stayed open.<br />
1511 Started to get flow from ESR<br />
1521 Dave requested that Cryo close the cold return from Hall B so that all return was to warm return to prevent warming the supply to the Hall through the transfer line.<br />
1530 Both magnets starting to cool down.<br />
1632 Cold return valve was opened from -5 to 0 %. Flow to Hall B dropped to 0 and magnets started to warm up.<br />
1641 Requested that Cryo close the cold return. Flow returned and magnets started to cool.<br />
1645 Buffer dewar relief valve still not seated. Requested that Cryo reduce the warm return pressure so relief valve could be reseated. Entered the Hall and applied heat to the buffer dewar relief valve with a heat gun and the valve reseated. The target relief valve also reseated as the warm return pressure was reduced.<br />
1744 Solenoid fully recovered. Torus average coil temperature returned to 5K, however reservoir was still empty. Notified Cryo that Hall B was stable and almost recovered. Cryo opened cold return valve.<br />
1815 Supply temperature started to increase and solenoid reservoir level began to decrease.<br />
1845 Requested Cryo close the cold return to reduce supply temperature and fill the magnets. Torus has yet to show any level in the reservoir.<br />
1940 Cryo called, ESR is having trouble recovering; we agreed to reduce flow to Hall B.</p>
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