[Dsg-mvt] News about Isobutane MFC
mdefurne
mdefurne at jlab.org
Wed Dec 20 18:03:22 EST 2017
Dear Amrit,
Thank you for your reply. The 10 premix bottles will be useful indeed.
I agree that the temperature for the isobutane must be stabilized since
it is killing MFCs because of the condensation. I noticed that the
insulation has been improved.
Our premix consumption depends highly on the beam availibility. We did
the last two weeks with only two premix bottles because accelerator had
issues. But I can only hope the beam will be fully available in January.
Using 24/24 premix, one premix bottle is expected to last 3.5 days. 10
bottles will then last about 5-6 weeks, accounting for some downtime of
Hall or accelerator. We will have to decide quite soon in January which
MFCs to buy if there is nothing we can do before.
Thanks everyone for your help. I wish you all a merry christmas and see
you next year.
Kind regards,
Maxime
Le 20/12/2017 à 17:27, Amrit Yegneswaran a écrit :
> hello maxime,
>
> your concerns are understandable.
>
> 1. Since the C4H10 temperature problem hasn't been solved, by buying
> new MFCs nothing is gained. If the gas condenses, the new MFC will
> stop working. Right?
> 2. Even if Marc, whose last day is tomorrow, orders the MFC tomorrow,
> the procurement department has to place the order for the MFCs,
> which by the time it is done, will be Januar2018.
> 3. Lead time for these MFCs is between 6 and 8 weeks, so the earliest
> you can expect them to arrive is mid/end of February 2018.
> 4. C4H10 temp. must be stabilized. On this matter much advise has
> been provided by George and much effort has been taken.
> 5. Marc has given the spare MFC to be installed. Hopefully, this works.
> 6. Upon their return in Jan, 2018, Marc and George will research
> other types of MFCs, which hopefully are impervious to
> condensation; recall even these will have a lead time of 6-8 weeks.
> 7. As a contingency, because the MVT gas system was so, so delayed, I
> asked George to order 10 premix bottles in November. As per Marc,
> these should arrive mid January. We can only hope that the come
> in time for the January run.
> 8. For the future, please e-mail your usage days/cylinder, so that
> George can order and adequate number of cylinders, at least until
> the MFC issue is resolved, or should one say solved?
>
> amrit
>
>
>
>
>
>
> ------------------------------------------------------------------------
> *From: *"Maxime Defurne" <mdefurne at jlab.org>
> *To: *dsg-mvt at jlab.org, "Bob Miller" <rmiller at jlab.org>, "burkert"
> <burkert at jlab.org>, "Yuri Gotra" <gotra at jlab.org>
> *Sent: *Wednesday, December 20, 2017 4:34:33 PM
> *Subject: *Re: [Dsg-mvt] News about Isobutane MFC
>
> Hi Marc, Hi Bob,
>
> 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.
>
> 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.
>
> Maxime
>
>
> Le 20/12/2017 à 11:23, Marc McMullen a écrit :
>
> Hi Maxime,
>
> 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).
>
> 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.
>
> 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.
> http://www.alicat.com/alicat-blog/products-and-services/liquid-in-a-gas-flow-controller-how-bad-is-it-doc/
>
> Finally, I have requested a status update from the premix vendor.
> When he responds I'll forward the info.
>
>
> Marc McMullen
> Physics Division
> Detector Support Group
> 7738
>
> ------------------------------------------------------------------------
> *From: *"mdefurne" <mdefurne at jlab.org>
> *To: *dsg-mvt at jlab.org
> *Sent: *Tuesday, December 19, 2017 11:26:33 PM
> *Subject: *[Dsg-mvt] News about Isobutane MFC
>
> Hi Marc,
>
> What is the schedule for the mixing system? Let me know if you need
> anything or think I could speed up one or two things.
>
> We are on the last premix bottle. We have to be ready for January
> 12th
> with either the gas mixing system or premix bottles (when will the
> ten
> bottles delivered?).
>
> Cheers,
>
> Maxime
>
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