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

[mdefurne]

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.
>
>
>
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