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Hi All,<br>
<br>
IMO, the only way to reduce gas loss due to ambient pressure changes
is to lower the pressure inside the detector. That will increase the
magnitude of pressure transient required to vent gas out the
bubbler. Therefor, I have reduced the pressure setpoint for gas flow
from 1.8"wc to 1.4"wc. That will increase the delta from where the
gas flow stops and where the gas is relieved out the bubbler. Once
the pressure in the detector falls to this value, we should check
the window shape to see if it can be set lower.<br>
<br>
This pressure setpoint will need reset to 1.8"wc prior to resuming
detector operation. Once the detector gas volume gas been refilled
to 1.8"wc, we can calculate gas usage during this period to
determine how effective this change was in saving gas.<br>
<br>
George<br>
<br>
<div class="moz-cite-prefix">On 3/9/2018 3:27 PM, Stepan Stepanyan
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:8101e440-a250-218a-a14d-66e8fda8d1ff@jlab.org">
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Hi George,<br>
<br>
OK, thank you.<br>
<br>
Stepan<br>
<br>
<div class="moz-cite-prefix">On 3/9/18 3:19 PM, George Jacobs
wrote:<br>
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cite="mid:465dd346-4f42-85b9-9ec4-b8896f1b7acb@jlab.org"
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Hi Stepan,<br>
<br>
The only way to keep the window inflated is to flow gas. We
could switch to N2 to maintain sufficient pressure to maintain
window shape. But, that may result in an increase is gas C4F10
loss during during N2 flow operation and again during the later
"topping off" process. Since we have not done this before, there
is no reference to point to. It does add an additional layer of
complexity to the activity.<br>
<br>
George<br>
<br>
<div class="moz-cite-prefix">On 3/9/2018 2:54 PM, Stepan
Stepanyan wrote:<br>
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<blockquote type="cite"
cite="mid:1FE0E147-0E44-4CEE-A25A-ED770A3B590C@jlab.org">
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George,
<div class=""><br class="">
</div>
<div class="">Thanks for the details. Yes, it seems not much
can be saved, but anything we can save is a plus. </div>
<div class="">Of course we cannot allow window come down on
mirrors. In that respect, is there a option to reduce the
loss?</div>
<div class=""><br class="">
</div>
<div class="">Regards, Stepan</div>
<div class=""><br class="">
</div>
<div class=""><br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Mar 9, 2018, at 2:23 PM, George Jacobs
<<a href="mailto:jacobsg@jlab.org" class=""
moz-do-not-send="true">jacobsg@jlab.org</a>>
wrote:</div>
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<div class="">
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charset=windows-1252" class="">
<div text="#000000" bgcolor="#FFFFFF" class=""> Ho
Mauri,<br class="">
<br class="">
An additional 2 weeks of running will result in a
decrease of ~7 kg gas from the supply tank, assuming
0.5kg per day usage.<br class="">
<br class="">
Currently, ~56 kg C4F10 remains in the supply tank.
This is a 112 day supply assuming 0.5 kg per day
usage.<br class="">
<br class="">
So, if we do nothing, in 2 weeks there will be ~49
kg C4F10 remaining in the tank. No change in
detector pressure. Same as now.<br class="">
<br class="">
If we do turn it off, there will be ~56 kg
remaining in the tank when we restart flow. Detector
pressure and fill will be reduced due to gas leakage
and the loss from ambient pressure changes during
the outage. The detector will need to be "topped
off" once we turn the gas back on. This will require
X amount of gas. Since X is unknown, but most likely
X < 7 kg and most definitely X > 0, the amount
of gas saved will definitely be < 7kg. So, we do
not know how much gas this will actually save. Once
gas flow is restarted, it may require 1-2 days to
refill. My only real concern is if the window
deflates to the point were it contacts and applies
pressure to the mirrors. That would be bad<br
class="">
<br class="">
I do not see much of a savings or advantage in
turning it off. But, that's not my call, it's yours.
We can turn gas flow off if you want it off. Let me
know what you decide. We will need to turn the gas
off at the supply tank.<br class="">
<br class="">
Cheers,<br class="">
George<br class="">
<br class="">
<div class="moz-cite-prefix">On 3/9/2018 11:03 AM,
Maurizio Ungaro wrote:<br class="">
</div>
<blockquote type="cite"
cite="mid:0094C616-BF59-40A8-A414-65928169E57C@jlab.org"
class="">
<pre class="" wrap="">Hi George,
We'll have a downtime in accelerator that may run for a couple of weeks.
In the spirit of saving as much gas as possible, what are our options?
Thanks,
Mauri
</pre>
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<br class="">
<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" moz-do-not-send="true">jacobsg@jlab.org</a>
(website) <a class="moz-txt-link-freetext" href="https://userweb.jlab.org/%7Ejacobsg" moz-do-not-send="true">https://userweb.jlab.org/~jacobsg</a></pre>
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</blockquote>
</div>
<br class="">
</div>
</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 moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:jacobsg@jlab.org">jacobsg@jlab.org</a>
(website) <a moz-do-not-send="true" class="moz-txt-link-freetext" href="https://userweb.jlab.org/%7Ejacobsg">https://userweb.jlab.org/~jacobsg</a></pre>
</blockquote>
<br>
</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>
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