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

[Marc McMullen]

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.
>>
>>
>>
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>

-- 
Marc McMullen
Detector Support Group
757-269-7738

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