<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
Hi All,<br>
<br>
It looks to me that the low pressure alarm setpoint is within the
normal ambient pressure transient range. This means you will get
alarms due to large ambient pressure changes. I would recommend
lowering the LO alarm setpoint to 0.050"wc and the LOLO to 0.030"wc
in order to minimize alarms due to ambient pressure changes.<br>
<br>
You may want to place guidance on how to respond to this alarm, for
example;<br>
- Verify gas flow is normal, currently 10 slm.<br>
- Verify the CO2 flow setpoint is correct<br>
- Verify the CO2 gas supply pressure is NORMAL<br>
- Verify CO2 gas supply dewars are not empty<br>
- Check ambient pressure to verify this is a result of an ambient
pressure change or a leak<br>
- Leaks will remain after the ambient pressure transient is
complete<br>
- Option of increasing the CO2 gas flow to 15-20 slm to speed up
recovery from the transient or make up for the leak<br>
<br>
Cheers,<br>
George<br>
<br>
<div class="moz-cite-prefix">On 4/16/2018 3:58 PM, Marc McMullen
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:288243cd-93f4-972e-fb16-d4f07975bbc4@jlab.org">Hi Denny
and Yuri,
<br>
<br>
I have checked the Mya archive, during the period of low pressure,
the mass flow controller was supplying 10lpm. It is set for 10lpm,
so no issue there. I have included 4 screenshots from MYA, three
are the same shot with different y-axis scales. One is a close up
of the event.
<br>
<br>
Also, that ambient pressure signal name is on the right side of
the graph, we use it a lot to check for coincidence with detector
pressures.
<br>
<br>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
Dsg-htcc mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Dsg-htcc@jlab.org">Dsg-htcc@jlab.org</a>
<a class="moz-txt-link-freetext" href="https://mailman.jlab.org/mailman/listinfo/dsg-htcc">https://mailman.jlab.org/mailman/listinfo/dsg-htcc</a>
</pre>
</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></pre>
</body>
</html>