[Dsg-mvt] [New Logentry] MVT Mixing System C4H10 Mass Flow Controller

[mdefurne]

The MFC stopped working although the heat tape was heating the isobutane 
pipe all along (The pipe was hot enough to slightly burn).  Is it 
possible that the exit pipe of the MFC must also be heated to prevent 
the isobutane from condensing on the other side of the MFC?

Cheers,

Maxime


Le 14/12/2017 à 17:39, Marc McMullen a écrit :
>
> Hi Max,
>
> I am not recommending the use of c4h10 in the new mfc until I can 
> prove the old one can be dried out or we get a new one, it is the 
> spare and we don't have another in that range. Tomorrow I'll submit an 
> order for a replacement.
>
> The liquid had to be isobutane, it evaporated as it was exposed to 
> air. Todd is looking into improvements to the thermal tape. Isobutane 
> needs to be above 70F to keep it from condensing. Todd also may be 
> able to set up a test for mixing Ar/C4H10. But the owner/da may have 
> to look into that first.
>
> Marc
>
>
> On 12/14/2017 4:46 PM, mdefurne wrote:
>>
>> Hi Marc,
>>
>> Just for curiosity, when will you try the death test, the test with 
>> isobutane? :P
>> I am also very curious about this fluid seen by Todd. Liquid 
>> isobutane? Unlikely considering the temperature of the MFC, no?
>>
>> Thanks again for investigating this issue.
>>
>> Max
>>
>>
>> Le 14/12/2017 à 16:25, mcmullen at jlab.org a écrit :
>>>
>>>
>>>   MVT Mixing System C4H10 Mass Flow Controller
>>>   <https://logbooks.jlab.org/entry/3504568>
>>>
>>> Lognumber 3504568 <https://logbooks.jlab.org/entry/3504568>. 
>>> Submitted by mcmullen <https://logbooks.jlab.org/user/mcmullen> on 
>>> Thu, 12/14/2017 - 16:21.
>>>
>>> Logbooks: 	HBMVT <https://logbooks.jlab.org/book/hbmvt>
>>> Entry Makers: 	mcmullen, jtewing
>>>
>>> We purged the mix 2 C4H10 mass flow controller with Argon this 
>>> morning (venting to atmosphere). During the disconnection Todd saw a 
>>> small amount of liquid drain from the mfc. It responded to flow set 
>>> points routinely above 150sccm. Below that value the flow was 
>>> between 90 - 100sccm, with the internal valve in the closed 
>>> position. The mfc was then zeroed by the manufactures procedure, 
>>> which specifies that is isolated from flow. The procedure went as 
>>> standard, however once the Argon supply was opened, the ~90-100sccm 
>>> flow returned. Proper operation below 150sccm was not achieved.
>>>
>>> The gas pad temperature reading was > 50F. The RTD was being read 
>>> from inside the enclosure. The MFC temperature reading was ~32C. 
>>> Both of the reading were within operating specs for the mfc.
>>>
>>> Around 1pm we swapped it out for the spare, which tested perfectly 
>>> in the lab.
>>>
>>> Once online we were able to flow Argon to the mfc low limit of 
>>> 13.9sccm at the set full scale (1390sccm). Even a little below that, 
>>> the mfc did not become unstable until < 10sccm. We then ran the mix 
>>> 2 system with both mfcs, still venting to atmosphere. Again no 
>>> issues with either mfc, as long as the C4H10 mfc set point was > 10sccm.
>>>
>>> Tomorrow I will test the bad mfc in the lab to see if I can dry it 
>>> out with either N2 or Ar.
>>>
>>>
>>>
>>> _______________________________________________
>>> Dsg-mvt mailing list
>>> Dsg-mvt at jlab.org
>>> https://mailman.jlab.org/mailman/listinfo/dsg-mvt
>>
>
> -- 
> Marc McMullen
> Detector Support Group
> 757-269-7738

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/dsg-hallb_mvt/attachments/20171214/a108445e/attachment-0002.html>