[Dsg-mvt] Alarm temperature MFC

[Brian Eng]

The MFC temperature is inside the MFC unit itself, but the company wouldn't tell me where exactly.

However, they did say it is _not_ the temperature of the gas. We'd need to order a different MFC if that's something important to monitor.

It does however follow the ambient temperature quite closely. It should be kept fairly stable as big changes will effect the actual flow (it should be kept around the temperature it was zero'd at). What the manufacturer said they use it for is calibration, i.e. wait for the unit to warm up and become stable and then do the measurements.

The company only gives specifications on the ambient operating temperature of the units not the internal one.

See attached plots: ambient is in F, the MFC is in C, and they're using the same scale.



> On Apr 16, 2018, at 9:14 AM, DEFURNE Maxime <maxime.defurne at cea.fr> wrote:
> 
> Dear all,
> 
> I guess the MFC may get warmer because of its own electronics and possibly because of the isobutane temperature. Does it need to be cooled down?
> Also do we have any idea about the conséquences of having a MFC temeprature higher than 50C? If it can change the mixture, it needs to be kept below the 50C. 
> 
> Kind regards,
> 
> Maxime
> ________________________________________
> De : Robert Miller [rmiller at jlab.org]
> Envoyé : lundi 16 avril 2018 15:01
> À : Brian Eng
> Cc : Nathan Baltzell; Guillaume Christiaens; DEFURNE Maxime; fbossu
> Objet : Re: Alarm temperature MFC
> 
> All,
> 
> The heating blanket that is on the isobutane bottle is designed to heat the bottle to 80-120F (27-49C).
> 
> What is the maximum operating temperature of the MFCs?
> 
> Also, the temperature of the probe placed next to the MFC reads 77F (25C), but the mix temperature reads almost 40C.  Where does the mix temperature come from?
> 
> Thanks,
> Bob
> 
> ----- Original Message -----
> From: "Brian Eng" <beng at jlab.org>
> To: "Nathan Baltzell" <baltzell at jlab.org>
> Cc: "Guillaume Christiaens" <guillaum at jlab.org>, "DEFURNE Maxime" <Maxime.Defurne at cea.fr>, "fbossu" <fbossu at jlab.org>, "Bob Miller" <rmiller at jlab.org>
> Sent: Friday, April 13, 2018 4:44:19 PM
> Subject: Re: Alarm temperature MFC
> 
> The alarm value can be raised if this becomes an issue.
> 
> We originally used the ambient temperature specs as the initial values, but these temperatures aren't really ambient.
> 
> Keeping the isobutane from condensating is more important since we know that can damage the MFCs, we don't yet know yet how the temperature effects the MFCs.
> 
> ----- Original Message -----
>> From: "Nathan Baltzell" <baltzell at jlab.org>
>> To: "Guillaume CHRISTIAENS" <guillaum at jlab.org>
>> Cc: "DEFURNE Maxime" <Maxime.Defurne at cea.fr>, "Francesco Bossù" <fbossu at jlab.org>, "Brian Eng" <beng at jlab.org>, "Bob
>> Miller" <rmiller at jlab.org>
>> Sent: Friday, April 13, 2018 2:15:36 PM
>> Subject: Re: Alarm temperature MFC
> 
>> Yes, alarm limit is 50, and it’s sitting just a bit above it.
>> 
>> Apparently this is not on a gui.  I’ll add it to the mixing one ...
>> 
>> 
>> 
>>> On Apr 13, 2018, at 14:11, Guillaume CHRISTIAENS <guillaum at jlab.org> wrote:
>>> 
>>> Dear all,
>>> 
>>> We just got an alarm on the temperature of gas MFC for mix1 and mix2 isobutane.
>>> I cannot access the values of the temperatures, but I guess temperature is too
>>> high. Can you please check Nathan (alarm should be still in the alarm handler)
>>> ?
>>> If no-one changed it, heat tape was supposed to be about 30%.
>>> I think we can change it to 15 % ? Do you think it would be fine ?
>>> 
>>> Regards
>>> Guillaume

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