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This is just for general knowledge.<br>
<br>
--- The purpose of an interlock is to either;<br>
#1 Protect from something "bad"<br>
or<br>
#2 Prevent something "bad"<br>
<br>
Now for the obvious question, What does the LOW N2 flow interlock
either, #1 Protect? or #2 Prevent? Nothing I can determine, but it
did turn off the detector for no real reason and perhaps ruin the
data from that run.<br>
<br>
--- The purpose of an alarm is to warn and or inform the
shift/oncall persons to investigate and/or troubleshoot. In this
particular situation, perhaps an alarm would be more useful than an
interlock.<br>
<br>
IMO, interlocks which do not protect or prevent bad things are self
defeating. This case is a good example. However, a properly set up
alarm would be my preference if it were my experiment.<br>
<br>
Cheers,<br>
George<br>
<br>
<div class="moz-cite-prefix">On 04/11/2018 08:30 AM, Tyler Lemon
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1341673655.4019601.1523449816020.JavaMail.zimbra@jlab.org">
<div style="font-family: times new roman,new york,times,serif;
font-size: 12pt; color: #000000">
<div>Hello George,<br data-mce-bogus="1">
</div>
<div><br data-mce-bogus="1">
</div>
<div>This morning, RICH interlocks tripped on low N2 flow as
noted in logbook entry 3558672
(<a class="moz-txt-link-freetext" href="https://logbooks.jlab.org/entry/3558672">https://logbooks.jlab.org/entry/3558672</a>). </div>
<div><br data-mce-bogus="1">
</div>
<div>Looking at the flow history, it shows that the nitrogen
flow dropped from 20 slm to 15 slm in about ten minutes. About
ten minutes later, the flow had increased again to 20 slm, but
has been unstable in comparison to before the drop in flow. We
checked other detector's nitrogen flows and the only other we
saw this on was the FT-calorimeter.<br data-mce-bogus="1">
</div>
<div><br data-mce-bogus="1">
</div>
<div>Attached is a plot of the two RICH N2 flows and one
FT-calorimeter N2 flow. The main point of the plot is to show
the three nitrogen flows all showed the same flow patterns, so
the plots are tiled to show all three signals. The Y-axis is
for the blue RICH N2 flow #2. The FT-calorimeter's flow is
significantly less, on the order of ~250 sccm, but its flow
still show the same drop and instability.<br
data-mce-bogus="1">
</div>
<div><br data-mce-bogus="1">
</div>
<div>What would cause this change in flow? Could it be caused by
Hall B's nitrogen dewar being refilled?<br>
</div>
<div><br data-mce-bogus="1">
</div>
<div>Best regards,<br data-mce-bogus="1">
</div>
<div>Tyler<br data-mce-bogus="1">
</div>
</div>
<br>
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<br>
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
George Jacobs
Jefferson Lab (TJNAF)
STE 12
12000 Jefferson Ave.
Newport News, VA 23606
(office) 757-269-7115
(cell) 757-876-0480
(email) <a class="moz-txt-link-abbreviated" href="mailto:jacobsg@jlab.org">jacobsg@jlab.org</a>
(website) <a class="moz-txt-link-freetext" href="https://userweb.jlab.org/~jacobsg">https://userweb.jlab.org/~jacobsg</a>
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