[Dsg-mvt] APPARENTLY no isobutane anymore upstream of MFCs

[mdefurne]

Dear all,

We are currently using Argon to test the FTT damged during the 
installation. Around 2pm, the test will be finished. But I think it is 
better to wait until 5pm, when temperature will get colder. 
Nevertheless, if someone wants to attend it and will not be available at 
5pm, we can do it at 3pm.

Let me know if you prefer 3pm. Otherwise, let's meet in the counting 
house at 5:00pm.

Kind regards,

Maxime


Le 10/01/2018 à 11:08, burkert a écrit :
> Maxime,
>
>  See if you can get the people together for a show and tell. I would 
> be interested in attending.
>
> Volker
>
> On 1/10/18 10:18 AM, mdefurne wrote:
>>
>> Dear all,
>>
>> _*Before all explanations, I want to emphasize that Maxence and I are 
>> not gas experts. So we are just explaining you what we did,why we 
>> think it seems to be safe to make another test of the mixing system 
>> with isobutane. We decline any responsability if something goes wrong 
>> and final approval to start using mixing system with isobutane must 
>> come from the JLab staff in charge of it. *_
>>
>> Last night with Maxence, we did the following procedure:
>>
>> - Closed all the valves.
>>
>> - Closed the manometer for the argon supply.
>>
>> From this state where everything is closed, we opened the valve in 
>> the rack on the isobutane line supply and then filled the line from 
>> the isobutane bottle to the upstream valve of MFCs with isobutane. 
>> The pressure was about 25psi (cannot be more precise since the heat 
>> tape was ON at 15% at that moment... when heat tape is warming, 
>> pressure is increasing in the line).
>> Then we closed the bottle and left the system in this state 
>> overnight, i.e. all the line insulated with heat tape around at 15% 
>> filled with isobutane.
>>
>> This morning we went to purge the line. To do so, we first open the 
>> relief valve and then we open the one of the valves allowing to purge 
>> with argon the isobutane MFC line. It is important to first open the 
>> relief valve, otherwise isobutane will first flow in a line which is 
>> not insulated and condense within a few seconds. (you tried it 
>> yesterday evening and relief valve was then spitting liquid and gaz. 
>> So 30F with no insulation will make isobutane condensing quite fast.)
>>
>> So this morning, only gaseous isobutane was exiting the relief valve. 
>> Apparently it seems that isobutane is not condensing anymore. And 
>> once the relief valve is closed, pressure in the line stayed at 0 
>> (With liquid in it, I would expect to have some pressure built in the 
>> line). I nevertheless insist on the "apparently" since the relief 
>> valve is not exactly on the isobutane line.
>>
>>   So, considering all this, I would _*only recommend*_ to start 
>> testing the mixing system with isobutane again. But _*final approval 
>> must be given either by a staff of JLab since this system is JLab 
>> responsability.*_
>>
>> If you want a demonstration of the test later today (because the mail 
>> might not be very clear without the rack in front of you), we can 
>> organize it. However, I have not a faintest idea about what the next 
>> test is to ensure that isobutane is gaseous, except going through one 
>> MFC (no need to start using both immediately and risk to lose both of 
>> them).
>>
>> Finally, 15% for the heat tape seems fine for ~30F. But temperature 
>> will get colder over the week end and next week. We might consider to 
>> run safe, i.e. testing again isobutane state as soon as we hit a new 
>> minimum of temperature.
>>
>> Kind regards,
>>
>> Maxime
>>
>
>
>
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