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Dear all,
<div class=""><br class="">
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<div class="">while I am still not convinced that MFC104 works properly, we may be able to create a work-around (and leave it in place as is) if Brian can give us detailed instructions how regular (BONuS12) users can change the valve setting on that MFC manually.
In other words, if we can somehow force the valve to open 100% irrespective of the flow rate readback, we can speed up the filling by roughly a factor of 2. I am willing to write detailed operation instructions for the RTPC experts on duty to optimize the
filling of the target once that information is available.</div>
<div class=""><br class="">
</div>
<div class=""><b class="">Our highest priority right now is to cable up the RTDs in the new RTPC3 - see Jiwan’s email below. We MUST have this done before we start recabling the RTPC, so this is now on our critical path to get ready for beam on schedule. Please
identify a person that can come in NOW to do this. </b></div>
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<div class="">Thank you, and good health and best greetings to all - Sebastian</div>
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<blockquote type="cite" class="">
<div dir="auto" style="font-family: TimesNewRomanPSMT;" class="">Dear Marc,
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<div dir="auto" class="">To get out from CVT cart we need about 2m cables. We also need 2 such, as we have two RTDs which should come out of CVT cart. From there to the CPU, we have cable from Rtpc1 which can be reused. </div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">Thank you,</div>
<div dir="auto" class="">Jiwan</div>
<br class="">
<br class="">
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Mar 17, 2020, 08:34 Marc Mcmullen <<a href="mailto:mcmullen@jlab.org" class="">mcmullen@jlab.org</a>> wrote:<br class="">
</div>
<blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-style: solid; border-left-color: rgb(204, 204, 204); padding-left: 1ex;">
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<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;" class="">
Good Morning Jiwan,</div>
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<br class="">
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<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;" class="">
As you are aware the Lab has started MEDCON 5, which requires us to work from home. So I will forward your request to the mailing list and contact the DSG manager for guidance. Essentially, you need 2 of the 4 wire RTD cables to be extended. How long do you
need these cables to be? In the future, please send work requests directly to the dsg-rtpc mailing list to ensure a wide distribution of the request to the entire DSG.</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;" class="">
<br class="">
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<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;" class="">
Regards,</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;" class="">
Marc<br class="">
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<div id="m_6870661274056705804appendonsend" class=""></div>
<hr style="display: inline-block; width: 877.4375px;" class="">
<div id="m_6870661274056705804divRplyFwdMsg" dir="ltr" class=""><font face="Calibri, sans-serif" color="#000000" style="font-size: 11pt;" class=""><b class="">From:</b> JIWAN POUDEL <<a href="mailto:jpoud001@odu.edu" target="_blank" rel="noreferrer" class="">jpoud001@odu.edu</a>><br class="">
<b class="">Sent:</b> Tuesday, March 17, 2020 8:22 AM<br class="">
<b class="">To:</b> Brian Eng <<a href="mailto:beng@jlab.org" target="_blank" rel="noreferrer" class="">beng@jlab.org</a>>; Marc Mcmullen <<a href="mailto:mcmullen@jlab.org" target="_blank" rel="noreferrer" class="">mcmullen@jlab.org</a>><br class="">
<b class="">Cc:</b> Eric Christy <<a href="mailto:christy@jlab.org" target="_blank" rel="noreferrer" class="">christy@jlab.org</a>><br class="">
<b class="">Subject:</b> [EXTERNAL] RTDs in RTPC3</font>
<div class=""> </div>
</div>
<div class="">
<div dir="auto" class="">Dear Brian and Marc,
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">We are in the process of replacing Rtpc1 by rtpc3. We decabled Rtpc1 yesterday and ready to put rtpc3 on cvt cart. There is survey for target from 9am to 1pm today, then we will start cabling the RTPC in the afternoon. Could you please
help us to extend the RTD cables out from CVT cart? The cables are not long enough and also have no connectors to extend. It is also hard to access RTDs after re-cabling. So we need to fix this before cabling is done.</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">Thank you,</div>
<div dir="auto" class="">Jiwan</div>
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<span style="font-family: TimesNewRomanPSMT;" class="">_______________________________________________</span><br style="font-family: TimesNewRomanPSMT;" class="">
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<blockquote type="cite" class="">
<div class="">On Mar 17, 2020, at 9:54 AM, Brian Eng <<a href="mailto:beng@jlab.org" class="">beng@jlab.org</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div class="">Just to add a bit more information on the MFC temperature.<br class="">
<br class="">
We could never get from the manufacturer where the measurement is physically located on the unit. However, It should be quite a bit higher than ambient, normally they will run around the factory calibration temperature 40°C. Since this MFC is outside it will
have much bigger temperature swings and generally track what the outside is doing plus some offset.<br class="">
<br class="">
However, from the specs the temperature coefficients are fairly low. The zero is <0.05% F.S./°C and the span is <0.08% Reading/°C (F.S. = 200 sccm). The only potential in this is that the MFC operating range is 10-50°C, which MKS has basically said that they
can't guarantee to meet specs at temperatures outside that but the MFC will still function.<br class="">
<br class="">
Note that we see this same effect on the LTCC MFCs located down in the hall (gas flow = lower temp), albeit less extreme. So far as I know there aren't any issues with that system not to mention those are in a temperature controlled location.<br class="">
<br class="">
We will certainly try our best to help with setting up a spare MFC if that is what is decided on.<br class="">
<br class="">
________________________________________<br class="">
From: Sebastian Kuhn <<a href="mailto:kuhn@jlab.org" class="">kuhn@jlab.org</a>><br class="">
Sent: Tuesday, March 17, 2020 9:18 AM<br class="">
To: Brian Eng<br class="">
Cc: <a href="mailto:dsg-rtpc@jlab.org" class="">dsg-rtpc@jlab.org</a>; Bob Miller<br class="">
Subject: Re: [New Comment] MFC104 seems flaky<br class="">
<br class="">
Dear Brian,<br class="">
<br class="">
I am starting to think that you are right and it is really the temperature reading that is totally off. I didn’t pay much attention to that before, but of course it makes sense that the calibration depends on temperature.<br class="">
<br class="">
For the record, at this moment the temperature reading from MFC104 is 33.75 (both numerical read-out and on the strip chart - this is similar to what your sample strip chart shows - the color of the axis labels is the same as that for the temperature curve).
This corresponds to 93 Fahrenheit - while the ambient air temperature in the shed right now should be below 50 F and hasn’t been much higher than that in the past (when you recorded that chart).<br class="">
<br class="">
Given that this does make the MFC work unreliably, I DO want it swapped out if at all possible (i.e., if people can come in to do it). Please let us know what we need to do, if there is any spare, and if anyone can do the swap (it will have to be done by a
competent person - a.k.a. not a user - as to not compromise the high pressure qualification of the system).<br class="">
<br class="">
Thank you - Sebastian<br class="">
<br class="">
<br class="">
<blockquote type="cite" class="">On Mar 16, 2020, at 9:45 PM, Brian Eng <<a href="mailto:beng@jlab.org" class="">beng@jlab.org</a>> wrote:<br class="">
<br class="">
I didn't bother with labeling those screenshots, but the temp from MFC is in C and outside temp is in F. Also they're not on the same Y-axis since all the PVs in that plot are tiled (the bolded PV in the legend is the one that the axis applies to). The plots
were just to show generally the MFC temp follows the outside temperature except when there is gas flowing.<br class="">
<br class="">
If there was an issue with the communication between the MFC and LabVIEW the cRIO would stop communications and throw an error. It's what drives the initialization count, 3 errors and it gives up trying to communicating and requires resetting the connection.
That I'm confident isn't an issue.<br class="">
<br class="">
Temperature is an easy one since this is a thermal based MFC if the temperature of the unit was wrong the flow reading would be as well. Which is why that temperature reading is even available at all, the factory uses it to calibrate at a known level (I believe
it is 40 C). So the flows will be off when the temperature is different from that. I'll check the specs tomorrow regarding what the temperature effect is. In the past we've only cared about the temperature is when the gas itself is temperature sensitive.<br class="">
<br class="">
Maybe I misunderstood your earlier emails or you put the wrong valve (SVBT 100, 102, 108), but from the ones you listed there's not just a few short pieces of plumbing, there's all the hundreds of the feet between the gas pad and panel in addition to the orifice
in the MFC itself, which complicates things. Also, from my previous email I forgot to prefix the valves with MVBT, i.e. the manual valves before and after the MFC.<br class="">
</blockquote>
<br class="">
I understood what you are saying. I am just reiterating that to sustain a REAL flow of 200 sccm, you need to have a significant reservoir of volume on BOTH sides of the flow meter (to flow FROM and to flow INTO), not just on the downstream side (the hundreds
of feet of gas line between pad and gas panel that you refer to). If SVBT100 and 102 are closed (never mind 108), then the UPstream volume is hardly more than a few 10’s of ccm (I estimate 30 ccm) so after a minute that volume would be totally depleted at
200 sccm.<br class="">
<br class="">
<blockquote type="cite" class=""><br class="">
I'm not saying the MFC isn't the cause, just that none of the signals that are available aren't pointing towards a failure we've seen before.<br class="">
________________________________________<br class="">
From: Sebastian Kuhn <<a href="mailto:kuhn@jlab.org" class="">kuhn@jlab.org</a>><br class="">
Sent: Monday, March 16, 2020 8:24 PM<br class="">
To: Brian Eng<br class="">
Cc: <a href="mailto:dsg-rtpc@jlab.org" class="">dsg-rtpc@jlab.org</a><br class="">
Subject: Re: [New Comment] MFC104 seems flaky<br class="">
<br class="">
Dear Brian,<br class="">
<br class="">
I totally understand that, given the extraordinary circumstances, you do not want to come in to try to check the MFC yourself. As I said, we can continue as is, although it will cost us a few hours of beam time (if there WILL be any beam time by the time the
RTPC switchout is complete ;-).<br class="">
<br class="">
On the other hand, I do NOT understand why you keep insisting that<br class="">
<blockquote type="cite" class="">nothing I've seen in the archived data would lead me to believe anything is wrong with the MFC itself<br class="">
</blockquote>
Yes, there is a long gas line on ONE (outlet) side of the MFC, but only a few short pieces of steel plumbing on the OTHER side. If I close all valves on that side, there should be no way that gas can still flow (FROM this small volume) at 200 sccm for any appreciable
time, even if there is a (slight) pressure differential. And I also don’t see how your other ideas for possible culprits (temperature, gas type) can explain why 2 out of 3 fills in immediate succession take a long time, and then the 3rd one only a short time
(or sometimes the other way around). In other words, the behavior is NOT consistent from one moment to the next.<br class="">
<br class="">
I may be misunderstanding something fundamental about the whole setup, but I am pretty sure that either there is some issue with the MFC itself (which, btw, appears for He, H2, D2 and N2 - not just for one specific type of gas), or an issue with communications
between the MFC and the Labview program. I’d be happy to be given an explanation that makes sense or instructions on how to FIX it - otherwise we’ll just live with it (there is too much other stuff to do with the BONuS switchover for our group of users to
also do some of the tests you suggest).<br class="">
<br class="">
Best greetings - Sebastian<br class="">
<br class="">
P.S.: It’s also not confidence-inspiring that the MFC temperature readback is about 10 or more degrees F lower (even without anything flowing) than the surrounding air.<br class="">
<br class="">
<br class="">
<br class="">
<blockquote type="cite" class="">On Mar 16, 2020, at 7:38 PM, Brian Eng <<a href="mailto:beng@jlab.org" class="">beng@jlab.org</a>> wrote:<br class="">
<br class="">
Hi Sebastian,<br class="">
<br class="">
A few comments sections below.<br class="">
<br class="">
When closing only 100, 102 & 108 I'm not surprised there was still flow as that means the entire length of tubing from the gas pad to the gas panel was "seen" by the MFC so any unequal pressure would cause flow. If you closed all the valves on the gas pad (100,
102 & 104) and still saw flow then it would be more cause for concern.<br class="">
<br class="">
<br class="">
<br class="">
I'm not sure if pressure systems allows for this, but an easy test would be to install a N2 calibrated rotameter after the MFC with the other side open to atmosphere and adjust the rotameter up/down when flowing and compare that to what the MFC reports back.<br class="">
<br class="">
<br class="">
<br class="">
Something that can be checked is to verify the gas selected matches what the gas the MFC thinks it should be flowing. On the same computer that the controls are being run from open a web browser and go to
<a href="http://hb-mfc-bonus-target.jlab.org" class="">http://hb-mfc-bonus-target.jlab.org</a><br class="">
<br class="">
If you see a green bar about the gas being changed near the top just refresh the page. If the gas there doesn't match the actual gas flown that would explain the times not matching up.<br class="">
<br class="">
However, I'd be extremely surprised at this being the problem as this is most likely to manifest itself when changing gases and ending up with something wrong, but not just changing for no reason if someone isn't messing with it.<br class="">
<br class="">
<br class="">
<br class="">
The only even remotely fishy thing I've seen is that on that on some of the fill cycles the temperature of the MFC dropped more than usual when purging. My guess, the outside temp & gas bottle itself was cold so the cold gas caused the MFC temp to drop more.
A few things to keep in mind though: 1) generally a drop in temperature is seen during the purge cycle, though not always as big of a dip nor to that level 2) the temp reading by the MFC is normally only used for calibration so it's readings should be taken
with a grain of salt 3) it could just be a red herring and have nothing to do with anything. I only bring it up as food for thought.<br class="">
<br class="">
<br class="">
<br class="">
I believe there is a MFC available (not sure on the capacity) and hopefully I can remotely walk through the steps with whoever is available to install it on getting the networking setup on one if that ends up being the solution<br class="">
<br class="">
<br class="">
<br class="">
Again, nothing I've seen in the archived data would lead me to believe anything is wrong with the MFC itself.<3-15 purge.png><br class="">
</blockquote>
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</blockquote>
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<span id="cid:B23126EF-42A9-4ABE-A204-8ECE0EB0D513@jlab.org"><LTCC MFC Temp.PNG></span></div>
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