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There were a couple of issues;<br>
<br>
-> Transducer Failure<br>
There was a hihi alarm for mix#1 storage tank. The problem
associated with too high a pressure in the tank is typically, that
the CO2 supply pressure is too low to flow the sufficient gas to
produce a 10% CO2 in argon mixture. The mix#1 pressure transducer
failed, resulting in a rapidly changing signal that crisscrossed the
alarm sepoint, resulting in multiple alarms. I have installed a
replacement, and am waiting for the new signal to be set up in the
cRio. <br>
<br>
-> CO2 Pressure is too low to maintain 10% mix ratio.<br>
CO2 dewars arrive with a variety of pressures, from pressure too
low to use as is, to some with pressure too high and already venting
from the relief valve. The DC Gas mixing system CO2 supply must be
monitored several times daily to insure proper mixing system
operation. If the CO2 pressure is too low, the 10% mix ratio will
not be 10%. In order to closely monitor the CO2 supply, I have
installed a new pressure transducer to monitor CO2 gas supply
pressure to the MFCs. There is a lolo alarm at 100 psi. This alarm
should be turned on. <br>
<br>
If you get this alarm, the following actions are required.<br>
1) Check that the CO2 supply pressure at the CO2 pressure regulator
outlet pressure gauge on the outside wall of the gas shed matches
the alarm value. <br>
2) Check the CO2 gas supply valves are open on the connected dewars,
flex lines, and pressure regulator outlet valves<br>
3) Check individual CO2 dewar pressures - carefully adjust the
pressure buildup valve to increase CO2 supply pressure (This takes
several hours to come to an equilibrium)<br>
4) Replace empty CO2 dewars<br>
5) Verify the CO2 pressure regulators on the gas shed wall are set
properly.<br>
<br>
George<br>
<br>
<div class="moz-cite-prefix">On 5/17/2017 5:43 PM, Denny Insley
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1034180356.5145313.1495057402410.JavaMail.zimbra@jlab.org">
<pre wrap="">Hello all,
Krister gave me a call this evening because he was getting constant alarms from DC-Gas. I logged in and took a look at
things and found the #1 mixing tank pressure and the C02 before the MFC's in major alarm. Both #1 and #2 CO2 flow indicators
show around 2lpm flow. Krister tried to call George, then talked to Bob. It was decided to wait till morning so I disabled both
alarms in the alarm handler so Krister could keep the phone on.
Denny
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<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>
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