[Dsg-mvt] Fw: Re: Re: Hall B: MVT gas mixture faults

[Amrit Yegneswaran]

thanks for informing me brian.

________________________________
From: beng at jlab.org <beng at jlab.org>
Sent: Saturday, February 15, 2020 2:35 PM
To: Amrit Yegneswaran <yeg at jlab.org>
Subject: Fwd: Re: Re: Hall B: MVT gas mixture faults

Been troubleshooting remotely, but need to go in to swap MFCs.

I'll post a long entry later.
---------- Forwarded message ----------
From: Bob Miller <rmiller at jlab.org>
Date: Feb 15, 2020 11:53
Subject: Re: Re: Hall B: MVT gas mixture faults
To: DEFURNE Maxime <Maxime.Defurne at cea.fr>,Yuri Gotra <gotra at jlab.org>,VANDENBROUCKE Maxence <Maxence.VANDENBROUCKE at cea.fr>,Brian Eng <beng at jlab.org>,Cyril Wiggins <cwiggins at jlab.org>
Cc:

I will come in around 1pm and check the system to see if liquid entered the MFC.

If there is no liquid, we will assume the MFC has failed.  If that is the case, I request that you come in Brian, to set up the MFC so I can replace it.

Maxime,

What is the purge flow rate for Argon and with the mix, and how long to purge each one?

Regards,
Bob
________________________________
From: DEFURNE Maxime <Maxime.Defurne at cea.fr>
Sent: Saturday, February 15, 2020 11:41 AM
To: Yuri Gotra <gotra at jlab.org>; VANDENBROUCKE Maxence <Maxence.VANDENBROUCKE at cea.fr>
Cc: Bob Miller <rmiller at jlab.org>
Subject: [EXTERNAL] RE:Re: Hall B: MVT gas mixture faults

Hi Yuri,

Indeed it seems that iC4H10 may have turned into liquid somewhere (The valve trying to close itself without controlling the flow is typical of what we had before + the temperature getting cold enough overnight and today).

Are you purging the system and all MFCs with Argon as indicated by Brian? Once it is done, the HV must not be turned ON for FMT before the detectors have been purged with a correct mix... otherwise the detectors may be damaged.

I hope MFC will recover.

Kind regards,

Maxime


________________________________
De : Yuri Gotra [gotra at jlab.org]
Envoyé : samedi 15 février 2020 17:21
À : DEFURNE Maxime; VANDENBROUCKE Maxence
Objet : Fwd: Re: Hall B: MVT gas mixture faults




-------- Forwarded Message --------
Subject:        Re: Hall B: MVT gas mixture faults
Date:   Sat, 15 Feb 2020 11:09:39 -0500
From:   Brian Eng <beng at jlab.org><mailto:beng at jlab.org>
To:     Cyril Wiggins <cwiggins at jlab.org><mailto:cwiggins at jlab.org>
CC:     Bob Miller <rmiller at jlab.org><mailto:rmiller at jlab.org>, Yuri Gotra <gotra at jlab.org><mailto:gotra at jlab.org>


Haven't found anything out of place on the software/control side.

cRIO has been online the entire time, no MFC timeouts, flow set points are correct.

Definitely looking more like a hardware (most likely MFC) issue, see the attached GUI.png image. The C4H10 valve is set to as low as it can to try and limit flow, but the flow is still way higher than it should be.

So the MFC is trying to regulate the flow but isn't/can't do it.

________________________________________
From: Brian Eng <beng at jlab.org><mailto:beng at jlab.org>
Sent: Saturday, February 15, 2020 10:52 AM
To: Cyril Wiggins
Cc: Bob Miller; Yuri Gotra
Subject: Re: Hall B: MVT gas mixture faults

The only thing I can think to do is vent off Mix 1 to make sure there isn't any liquid in the lines and maybe flushing with Argon up to the tank as well.

________________________________________
From: Cyril Wiggins <cwiggins at jlab.org><mailto:cwiggins at jlab.org>
Sent: Saturday, February 15, 2020 10:29 AM
To: Brian Eng
Cc: Bob Miller; Yuri Gotra
Subject: Hall B: MVT gas mixture faults

CVT > MVT overview > Interlocks
Fault: GasArFlowFrac
Fault: GasC4H10FlowFrac

Brian,

We have been having occasional spikes of these two variables, which would then settle back into the acceptable operating range.
Today, these values are reporting way out of range, and are staying that way. Their values show correctly at the gas-pad gauges, and their set-points are as expected in the gas shed.
Currently data is being taken with FMT off, but we need your help to figure out what is happening to cause this.

-Cyril




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