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

[mcmullen at jlab.org]

Logentry Text:
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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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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3504568
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