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<p>Hi Marc, Hi Bob,<br>
</p>
<p>Thank you for the information. We do not have much time to think
and we need to take quickly action. Indeed SVT is in critical
shape and without Micromegas, the CVT will be inefficient. If
there is no gas for January, it will be a major issue for CLAS12
commissioning.</p>
<p>Maybe is it better to order these new MFCs resisting to
condensation. How much are they? I think we should do the maximum
to order MFCs before the christmas holiday.<br>
</p>
<p>Maxime<br>
</p>
<br>
<div class="moz-cite-prefix">Le 20/12/2017 à 11:23, Marc McMullen a
écrit :<br>
</div>
<blockquote type="cite"
cite="mid:1982328490.89036.1513786994953.JavaMail.zimbra@jlab.org">
<div style="font-family: arial, helvetica, sans-serif; font-size:
12pt; color: #000000">
<div>Hi Maxime,<br>
</div>
<div><br data-mce-bogus="1">
</div>
<div>I have been running argon through the c4h10 mfc which was
removed from the mixing system. It is not functioning properly
after hours of purging. We will need to replace it. I'll
contact MKS today to see if they will repair it. We need to
buy at least two more (~$1600 per), because I believe the mix
1 c4h10 was not acting properly and was exposed to condensed
gas during the same time, although to a lesser extent. Testing
shows that the valve will no longer seat, so that if there is
any pressure (10-15psi) the mfc will flow 35 - 50 sccm. If I
close off the argon valve at the regulator, the flow bleeds
off, so I believe it's leaking through the internal valve
seat. If the mfc is mechanically isolated from gas, it
measures no flow, so the sensor seems to be ok. So a repair of
the internal components may be the fastest way to have a
second perfectly running mfc (4 week lead time on purchase). <br
data-mce-bogus="1">
</div>
<div><br data-mce-bogus="1">
</div>
<div>The other focus needs to be on insuring the gas will not
condense in the mfc. You should address this with the system
owner (Bob) and tech (Todd) on the best way to keep the gas
> 70degF. Although the mfcs are specified to operate down
to 50F, the gas may condense due to the small amount of flow.
The mfcs are sized correctly. So unless there is an objection
I will request the same size. <br data-mce-bogus="1">
</div>
<div><br data-mce-bogus="1">
</div>
<div>We may also consider going with an mfc which may have a
better recovery from this kind of issue. I read an article on
a different brand which may provide some solution in the
future.<br data-mce-bogus="1">
</div>
<div><a class="moz-txt-link-freetext" href="http://www.alicat.com/alicat-blog/products-and-services/liquid-in-a-gas-flow-controller-how-bad-is-it-doc/">http://www.alicat.com/alicat-blog/products-and-services/liquid-in-a-gas-flow-controller-how-bad-is-it-doc/</a></div>
<div><br data-mce-bogus="1">
</div>
<div>Finally, I have requested a status update from the premix
vendor. When he responds I'll forward the info.<br
data-mce-bogus="1">
</div>
<div><br>
</div>
<div><br>
</div>
<div data-marker="__SIG_PRE__">Marc McMullen<br>
Physics Division<br>
Detector Support Group<br>
7738</div>
<div><br>
</div>
<hr id="zwchr" data-marker="__DIVIDER__">
<div data-marker="__HEADERS__"><b>From: </b>"mdefurne"
<a class="moz-txt-link-rfc2396E" href="mailto:mdefurne@jlab.org"><mdefurne@jlab.org></a><br>
<b>To: </b><a class="moz-txt-link-abbreviated" href="mailto:dsg-mvt@jlab.org">dsg-mvt@jlab.org</a><br>
<b>Sent: </b>Tuesday, December 19, 2017 11:26:33 PM<br>
<b>Subject: </b>[Dsg-mvt] News about Isobutane MFC<br>
</div>
<div><br>
</div>
<div data-marker="__QUOTED_TEXT__">Hi Marc,<br>
<br>
What is the schedule for the mixing system? Let me know if you
need <br>
anything or think I could speed up one or two things.<br>
<br>
We are on the last premix bottle. We have to be ready for
January 12th <br>
with either the gas mixing system or premix bottles (when will
the ten <br>
bottles delivered?).<br>
<br>
Cheers,<br>
<br>
Maxime<br>
<br>
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