[Dsg-rich] [Rich] rich air flow

Sun Oct 14 15:19:12 EDT 2018

Hi all, 
I remember the same behavior when we started the system the first time. In other words I try to explain: if the air flow rate is set to the nominal value (the gate valve is open) and the air  tank is empty, when the compressor is switched on then the pressure vs time in the tank assumes exactly the same behavior you have posted so far and this behavior remains stable in  time. 
If the air flow rate to the rich is set to zero (gate valve is off), when the compressor is switched on and you wait until the pressure in the tank reaches the max value before opening the flow to the rich than  the pressure behavior vs time is stable. 
Why this behavior? I think there is an instability in the system that shows up when the tank pressure drops below a certain value. Someone should study the stability of the system (poles and zeros) to find out the limit parameters! I know it is not so easy! 
Hope it is clear. 
Sandro

⁣Inviato da BlueMail 

Il giorno 14 ott 2018, 19:16, alle ore 19:16, Brian Eng <beng at jlab.org> ha scritto:
>Unfortunately we don't currently have any way of independently
>monitoring the compressor status. From what I remember from initial
>testing the information that the web page contained was quite limited,
>but we should at least look again to see if it has when it is on/off.
>If not, maybe there is funding to get the communications module? I
>believe Tyler has already looked into that?
>
>So it could just be that the compressor was on the whole time trying to
>build pressure vs cycling on/off. It wasn't just the pressure that
>wasn't cycling the flows were pretty flat too. In any event, we're all
>just making guesses at this point though.
>
>I still think interlocking (and to a lesser extent the alarms) on the
>flows and especially the pressure when the temperatures are okay seems
>overly aggressive, especially with the values being so tight.
>
>----- Original Message -----
>> From: "Valery Kubarovsky" <vpk at jlab.org>
>> To: "Brian Eng" <beng at jlab.org>
>> Cc: "Tyler Lemon" <tlemon at jlab.org>, rich at jlab.org, "dsg-rich"
><dsg-rich at jlab.org>, "Marco Mirazita"
>> <Marco.Mirazita at lnf.infn.it>
>> Sent: Sunday, October 14, 2018 12:17:34 PM
>> Subject: Re: [Dsg-rich] [Rich]  rich air flow
>
>> Brian,
>> I think that if you switch off the compressor the pressure will drop
>very
>> rapidly (several minutes) independently of ambient pressure. Take a
>look to the
>> pictures. It may be a problem with pressure sensor or something
>connected with
>> that.
>> vk
>> 
>>> On Oct 14, 2018, at 12:05, Brian Eng <beng at jlab.org> wrote:
>>> 
>>> Valery,
>>> 
>>> It's actually the opposite, this cycling behavior is actually how it
>previously
>>> used to look (see overview plot). The "flat" flow/pressure is a
>relatively new
>>> phenomenon and it looks to be caused by the remnants of the
>hurricane coming
>>> through; lower ambient pressure causes higher differential pressure
>in the
>>> various gas volumes. Normally this shows up as the compressor
>cycling on/off
>>> less (see pre storm plots). Since the drop was so large it
>manifested as not
>>> even turning on.
>>> 
>>> The compressor used to get the tank to 120 psi, now it's only going
>to 110 psi,
>>> which is why the bottom part of the "spike" is lower.
>>> 
>>> However, the flow is basically the same as it was before: this
>points to the
>>> alarm and especially interlock values being to conservative or in
>many cases
>>> counter-productive as they'll shut off the detector and could result
>in a junk
>>> run prematurely.
>>> 
>>> Personally I would remove quite a few interlocks and loosen many of
>the alarms,
>>> but that decision should come from the detector exports.
>>> 
>>> ----- Original Message -----
>>>> From: "Valery Kubarovsky" <vpk at jlab.org>
>>>> To: "Tyler Lemon" <tlemon at jlab.org>
>>>> Cc: rich at jlab.org, "dsg-rich" <dsg-rich at jlab.org>, "Marco Mirazita"
>>>> <Marco.Mirazita at lnf.infn.it>
>>>> Sent: Sunday, October 14, 2018 11:02:15 AM
>>>> Subject: Re: [Dsg-rich] [Rich]  rich air flow
>>> 
>>>> Hi Tyler,
>>>> Look at zoom picture. Do you understand this behaviour?
>>>> I mean this sharp drop of the pressure.
>>>> Valery
>>>> 
>>>> 
>>>> 
>>>> 
>>>> From: "Tyler Lemon" <tlemon at jlab.org>
>>>> To: "Valery Kubarovsky" <vpk at jlab.org>
>>>> Cc: "Marco Mirazita" <Marco.Mirazita at lnf.infn.it>, rich at jlab.org,
>"dsg-rich"
>>>> <dsg-rich at jlab.org>
>>>> Sent: Sunday, October 14, 2018 10:28:51 AM
>>>> Subject: Re: [Rich] [Dsg-rich] rich air flow
>>>> 
>>>> 
>>>> 
>>>> Hi Valery,
>>>> 
>>>> I agree, the plot looks normal after 18:40 on October 13.
>>>> 
>>>> Attached is the same plot you shared, but with annotations showing
>the pressure
>>>> measurement any time the value looked to be under 40 psi. The
>lowest it seems
>>>> to have gotten was ~36 psi.
>>>> 
>>>> Also, the archiver doesn't ever show that the hardware interlock
>for the air
>>>> pressure ever tripped. It's low limit is set to 35 psi.
>>>> 
>>>> Best regards,
>>>> Tyler
>>>> 
>>>> 
>>>> From: "Valery Kubarovsky" <vpk at jlab.org>
>>>> To: "Tyler Lemon" <tlemon at jlab.org>
>>>> Cc: "Mirazita Marco" <Marco.Mirazita at lnf.infn.it>, rich at jlab.org,
>"dsg-rich"
>>>> <dsg-rich at jlab.org>
>>>> Sent: Sunday, October 14, 2018 10:15:03 AM
>>>> Subject: Re: [Rich] [Dsg-rich] rich air flow
>>>> 
>>>> Hi All,
>>>> I got several calls yesterday evening and today night from CLAS12
>shift about
>>>> AIRPR1 alarm (currently minimum set to 35). See attached plot. I
>changed this
>>>> limit to 30 for a moment. The plot looks not normal before Oct.13
>18:40 in my
>>>> view.
>>>> Regards,
>>>> Valery
>>> <post-storm.png>
>>> <pre-storm.png>
>> > <overview.png>
>_______________________________________________
>Dsg-rich mailing list
>Dsg-rich at jlab.org
>https://mailman.jlab.org/mailman/listinfo/dsg-rich
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/dsg-hallb_rich/attachments/20181014/c6d4f484/attachment-0002.html>