[Dsg-rich] [New Logentry] RICH compressor pressure decrease investigation

Wed Apr 10 11:12:56 EDT 2019

Marco,

Just as a FYI where those PVs come from and what they're measuring ...

B_SYS_WEATHER_OUT_Press - data comes from a Facilities Management weather station on top of Hall B (sometimes it has drop outs)  - units are in inHg (inch of mercury)
B_SYS_WEATHER_SF_L3_Press - data from an absolute baratron inside of Hall B (as indicated by the name it's on Space Frame Level 3) - units are in inH2O (inch of water column)

Valery,

I'd agree there is some correlation there, but maybe it's not particularly high (especially recently)?
However, the compressor is definitely acting differently since late Nov last year.

Previously the compressor would cycle on and off continuously, then only some of the time, now it never does.
All 3 periods are shown in correlation plots (couldn't do long durations with earlier dates because MyaPlot would sample the data to reduce the number of points, which means can't export as a correlation plot)
- 2018 Apr - compressor always cycling on and off
- 2018 Oct - compressor cycling on and off & periods of it not
- 2019 Feb - compressor never cycling

[cid:EF206C19-2E22-48AD-B15E-2258624836FD at jlab.org][cid:4FB69DF9-6DC5-41B2-BB87-243CF2715F0B at jlab.org][cid:94DD3907-0136-4661-BDE7-A9503DF4271E at jlab.org][cid:854622A8-D4A7-42EA-863D-557D0A7E4FA1 at jlab.org][cid:34E2CFD6-1ABC-4A48-82FD-28FE60E0FD9D at jlab.org][cid:90874DC9-A60A-432B-9020-FDE43D0B4AFD at jlab.org]

On Apr 10, 2019, at 9:39 AM, Valery Kubarovsky <vpk at jlab.org<mailto:vpk at jlab.org>> wrote:

Marco,
The correlation is visible. However, I noticed that Y-axis zero is suppressed.
So, for weather the ratio of max to min is 1.03 but for the RICH_INTLK_AIRPRESSURE1 this ratio is 1.9.
Regards,
valery

On 4/10/19, 08:16, "Dsg-rich on behalf of Marco Mirazita" <dsg-rich-bounces at jlab.org<mailto:dsg-rich-bounces at jlab.org> on behalf of Marco.Mirazita at lnf.infn.it<mailto:Marco.Mirazita at lnf.infn.it>> wrote:

Hi Tyler,
I just noticed this nice correlation between the RICH pressure readout
and what could be some Hall B environment pressure, in the mya viewer it
is called HB_WEATHER->B_SYS_WEATHER_OUT_Press.
Similarly if I plot WEATHER_L3_Press.
Not sure what does it mean though.
Marco

Il 2019-04-09 23:30 tlemon at jlab.org<mailto:tlemon at jlab.org> ha scritto:
RICH COMPRESSOR PRESSURE DECREASE INVESTIGATION [1]

* Edit [2]
* Delete [3]

Lognumber 3677358 [1]. Submitted by tlemon [4] on Tue, 04/09/2019 -
17:27 [5].

LOGBOOKS:
RICH [6]

ENTRY MAKERS:
beng, mcmullen

ATTACHED FILES:

RICH-air-compressor-investigation-photos_2019-04-09.pdf [7]

Valery called notifying of low air pressure alarms for RICH's air
cooling system. RICH air cooling buffer tank pressure had been
steadily decreasing and was alarming at ~30 psi.

At Valery's direction, we made an access to the hall to investigate
the cause.

In the hall, we noted that both the local pressure gauge on the
cooling system buffer tank and the pressure readout on the compressor
read ~80 psi (Fig 1 and Fig 2 in attachment). Because these two
readouts match, it appears that the pressure transducer used for
remote monitoring is not working correctly.

We left the compressor running and the system as we found it because:
1.) the cooling panel's regulators are set to lower than 80 psi (~35
psi for airflow 1 and ~30 psi for airflow 2; Fig 4 in attachment)
2.) airflows are close to their 500 slm and 400 slm set points (Fig 3
in attachment)
3.) the compressor's output pressure readback plot shows the pressure
has been stable at ~80 for several days (Fig 2 in attachment).

For now, Valery will lower the air pressure alarm and trip level to
avoid the system giving further alarms or tripping off the detector.
Airflow interlocks will remain at the same level.

After the run, we will look into replacing the pressure transducer on
the buffer tank and look further into why the compressor output
pressure has dropped.

As a side note, we also noticed the gauge on the compressor's output
filter was in the red (Fig 5 in attachment). This will also be
investigated after the run to see if the filter needs to be drained.

Links:
------
[1] https://logbooks.jlab.org/entry/3677358
[2] https://logbooks.jlab.org/entry/3677358/edit?destination=email/send
[3]
https://logbooks.jlab.org/entry/3677358/delete?destination=email/send
[4] https://logbooks.jlab.org/user/tlemon
[5]
https://logbooks.jlab.org/entries?start_date=1554841638&end_date=1554848838&book=RICH
[6] https://logbooks.jlab.org/book/rich
[7]
https://logbooks.jlab.org/files/2019/04/3677358/RICH-air-compressor-investigation-photos_2019-04-09.pdf

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