Choose timezone
Your profile timezone:
Gas systems weekly project meeting
→
Europe/Zurich
20/1-004 (CERN)
gas systems project meeting
Gas systems
Gas systems 2026-10-01
Key Outcomes
Multiple gas system issues were identified and partially resolved across ATLAS and CMS RPC systems. The RPC mixer at 904 is now operational after pressure troubleshooting. CLOUD software and regulation bugs remain open issues, with full resolution expected by end of next week. On-call (piquet) coverage was discussed for the Christmas period.
Incidents & Root Causes
· ATLAS RPC humidifier: Water level in reservoir dropped to below 40% (alarm threshold at 40%);
· ATLAS-TGC: a perforated pneumatic tube on the drain valve, which opened fully and redirected all CO₂ flow through the reservoir (ELOG - Atlas TGC alarme PCV4003 a 100%, fuite pneumatique).
· Root cause: Cold tubes passing through a wall formed ice, which over time crushed the pneumatic tubing; electrical cables share the same conduit, raising further concerns.
· Profibus card issues: Recurring problems noted; alarms deliberately not cleared pending investigation (example ELOG - Alice MCH alarme Profibus).
· CLOUD : A regulation error caused water to enter the chamber at >100°C, generating steam and disrupting flow control; membrane has since been replaced.
· CLOUD automatic drain malfunction: Outlet valve failed to close at the correct level, sending water into the chamber instead of gas.
System Status
· RPC mixer at 904: Now stable — line pressure raised to 100 mbar (was only 30 mbar with 10 rotameters open); flow at ~20 L/h total.
· RPC 904 Nitrogen humidifier: Connection planned for Monday; expected operational Monday afternoon.
· CMS software (PVSS): Non-functional until late August; heating regulation parameters were incorrect and required manual correction one by one. Most issues resolved; remaining bugs targeted for end of next week.
· Flashing lights at S62 control room: Started flashing unexpectedly during dismounting; likely a cut cable — action to remove power and physically dismount when available.
Open Issues & Risks
· CLOUD software bugs: Marc (software contact) unavailable; follow-up session planned for Monday.
· Purifier trend review: Pressure increase observed across all loop points; unclear if fault originated at purifier. Alarm logic delay may be 5 minutes, not 5 seconds — needs verification for CMS and all systems.
· CMS humidifier flow: Delivering only 15–20 g/h against a 100 g/h full-scale set point; purifier partially bypassed — ordering a replacement recommended.
· LHCb UT valve/pipe condition: Item on action list with unclear description; possibly relates to valve not opening or pneumatic pipe condition — needs clarification.
· LHCb UT flow stop behavior: When system is manually stopped, flow stops; needs check against functional analysis to confirm expected behavior.
· RPC differential pressure review: Econex inspection not yet scheduled — flagged as at risk of being deprioritized if not formally planned.
Action Items
· Louis-Philippe/Gianluca: Investigate and resolve remaining CLOUD software bugs with Marc — Monday session.
· Andrea: Notify RPC team to maintain line pressure at several hundred mbar minimum.
· Andrea: Connect nitrogen humidifier Monday; confirm operational by Monday afternoon.
· Patrick: Remove power to flashing lights at NA62; dismount when opportunity arises.
· Gianluca: Verified buffer pressure alarm delay unit (5 seconds vs. 5 minutes) in recipe.-> there is an issue in the recipe
· Andrea->Patrick: Order replacement CMS humidifier purifier (current unit insufficient at minimum flow).
· Andrea/Maria Cristina: Schedule Econex/RPC valve inspection
· Patrick/Stefania/Gianluca: Clarify LHCb UT pipe/valve condition item; check functional analysis for manual stop behavior.
· NA62 Straw: Fabio available for up to two days; Roberto to confirm based on bottle availability.
· Roberto: Prepare first batch of Christmas piquet schedule; confirm assignments next week.
Christmas Holiday On-Call (PK) Coverage
· Period: 23 Dec – early January (~14 days)
· Available personnel: Gianluca (from 23rd), Davide, Louis-Philippe, Andrea, Maria-Cristina, Patrick, Beatrice (avoid last 2–3 days of holidays)
· ~5–6 people available; assignments to be distributed roughly in alphabetical order; final schedule to be confirmed next week.
· Last regular piquet ends 22nd (maria Cristina); Gianluca's slot finishes 17th.
Gas systems 2026-09-24
Action Items
· Gianluca: Investigate PLC logic for minimum valve opening threshold below 10%. CMS-RPC humidifier
· Maria Cristina: Review purifier pressure trend; assess feasibility of dedicated purifier high-pressure alarm.
· Gianluca: Verify buffer pressure alarm delay unit (5 seconds vs. 5 minutes) in recipe.
· Davide/Roberto / Fabio: Proceed with NA62 Straw chamber disconnection; coordinate access permit with Roberto.
· Stefania (microcirculation): Order mechanical and electrical material; report estimated arrival at next meeting.
· Davide/Max/GIanluca: Execute Atlas isobutane mixture change starting ~5 October, allowing 3–5 days for stabilization.
· Davide/Max/Gianluca: Check historical pump test record to identify which pump had the prior current absorption problem ATL-MDT.
Gas systems 2026 09 17
Action Items
· Gianluca: Check PLC logic for humidifier mass flow controller minimum opening threshold (with Gianluca, back next week) CMS-RPC.
· Andrea: Order correct-scale mass flow controller for water injection (~20 g/hr max scale based on observed demand).
· Gianluca/Maria Cristina/Roberto: Review purifier differential pressure trend to determine if early blockage detection is feasible; consider adding dedicated alarm.
· Andrea/Maria Cristina: Inspect Econex valve seat from Rack 70 for aging/deformation; assess all seats for LS3 replacement. Not yet dismounted
· Davide/Max: Continue CO2 pressure-drop tests on Column B (Atlas-RPC) — check if drop rate decreases over repeated tests (saturation indicator). -> stable rate
· Davide: Perform full pump maintenance on all three RPC pumps (gasket material upgrade, needle valve replacement). -> done maintenance p2, non return completely broken. replaced. pump 2 still not ok after. Plan to replace all non-return
Gas systems 2026-09-03
Action Items
- Patrick/Gianluca: Investigate LHCb-UT, confirm correct logic and pipe (or valve or pneumatic pipes?) condition.
- Andrea : finalize TID and send link.
- Florian's mixer: Order required materials — planned for next week – who is ordering?
Fabio ongoingPatrick for electrical Andrea: uCL electrical part to put in the workshop planning w42-45 empty but full. now in week 46.
piquet:
LHCb pump filters to be changed or something (for LS3)-> TICKET
O2+H2O analyser to be checked -> TICKET
ATLAS-RPC rack 66 and 69 pressure alarm during purif 2 change over -> TICKET
NA62
glitch of CEDAR 6105, is it the keller? -> TICKET to check
ATLAS-TGC putifier Col B leak. loosing 1 bar in 1 day -> TICKET Davide check with Argon or CO2
CMS-DT pressure sensor PT1303 went to 0 for 20 minutes -> TICKET to follow Andrea
ATLAS-RPC purif -> affecting chamber pressure -> R66 check
12/2 ATL-RPC purif 1 some software issue and sms not indicating the right reason for the alarm -> TICKET
IR status, spares, .... --> TICKET
test binary gas analyser... -> TICKET
outcome of binary gas analyser test --> TICKET & buy a 2nd one --> Maria Cristina
DP pressure for pump filter in ALICE and LHCb -> TICKET -> @LPh + @Patrick [GASSYSTEMS-903] DP pressure for pump filter increasing - CERN Central Jira -> Stefania
chiller fluids to uniform between CMS, LHCb and ATLAS -> TICKET Maria Cristina
check if NV in purif is really useful --> TICKET
Calibration bottles O2-H2O status
ALICE
70 report from Anité [GASSYSTEMS-70] TPC gas quality - filters to Benoit - CERN Central Jira (I don't see the report, can you please add it?)
several alarms blocked: [GASSYSTEMS-628] ALICE alarms blocked - CERN Central Jira
TOF gas mixture analysis -> [GASSYSTEMS-639] TOF gas mixture analysis - CERN Central Jira & ELOG
TRD membrane is connected ? -> [GASSYSTEMS-717] TRD membrane status - CERN Central Jira
P&ID drawing check who is doing -> [GASSYSTEMS-736] ALICE P&ID drawing check - CERN Central Jira
MID swap of pumps during MD because sometime the system stop -> TICKET
ATLAS
MDT frequency converter (need to be replaced TICKET) ELOG - ATLAS MDT Test convertisseur 4101 avec la pompe 4201
RPC distribution rack regulation valve (TICKET)
RPC secondary mixer (TICKET), info to be given to ATLAS
RPC purif 3 circuit breakers & meeting -> [GASSYSTEMS-718] RPC purif 3 electrical issue - CERN Central Jira --> meeting when?
ATLAS-TGC flow difference --> [GASSYSTEMS-612] ATLAS-TGC flow difference - CERN Central Jira
CMS
RPC purif test at workshop, PLC needed -> TICKET
R134a insulation - isol'tut to check and see what to do -> ticket IO [GASSYSTEMS-578] R134a insulation - isol'tut to check and see what to do - CERN Central Jira
How much gas flow we need for the RPC purifier? --> [GASSYSTEMS-579] CMS-RPC How much gas flow we need for the RPC purifiers? - CERN Central Jira @MariaCristina notes to be added
RPC bypass pump too much closed --> [GASSYSTEMS-604] RPC bypass pump too much closed - CERN Central Jira
RPC with CO2 like ATLAS and effect on R134a recuperation -> [GASSYSTEMS-606] RPC with CO2 like ATLAS and effect on R134a recuperation - CERN Central Jira
R134a Upgrade (hardware and software) to be tested -> [GASSYSTEMS-594] R134a Upgrade (hardware and software) to be tested - CERN Central Jira
DT vaisala reading difference between SG and US -> [GASSYSTEMS-677] CMS DT vaisala reading difference between SG and US - CERN Central Jira
CMS-FGR -> TICKET should we add a module. Do we need to buy something? follow-up
CMS-FGR -> TICKET Maria Cristina già fatto per bypass
CMS-FGR -> TICKET flowmeter for Huber
CMS-RPC IR not stable -> elog Maria Cristina -> TICKET
CMS-ID flushing. refurbishing of old racks material and manpower need to be estimated -> TICKET @Gianluca ticket number for project
R134a huber temperature can be controlled by PLC -> TICKET
LHCb
TS1-> RICH1 leak search (postponed), SciFi some work from others expected
RICH1 what we learn from 1st fill -> [GASSYSTEMS-608] RICH1 what we learn from 1st fill - CERN Central Jira
summary of the C4F10 bottles --> TICKET or ELOG -> [GASSYSTEMS-660] summary of the C4F10 bottles - CERN Central Jira
alarms blocked: [GASSYSTEMS-631] LHCb alarms blocked - CERN Central Jira
RICH2 filter blocking -> [GASSYSTEMS-731] RICH2 pump filter differential pressure sensor not working - CERN Central Jira
P&ID drawing check who is doing -> [GASSYSTEMS-739] LHCb P&ID drawing check - CERN Central Jira
RICH1 cleaning , when? not before mid-september? -> TICKET
RICH1 remove membrane rack before end of HL-LHC operation and/or change piping-> TICKET
RICH2 injection through recuperated CF4 -> TICKET
fire detection alarms reported by Pieter, more info? but not on us. Cleaning of SG room -> TICKET
CODEX-b interlock for flammable gas detection -> Patrick
RICH1 leak repair -> December 9th tbc -> TICKET
NA62
CEDAR maintenance needed -> [GASSYSTEMS-609] CEDAR maintenance needed - CERN Central Jira
change of pressure sensor used for leak warning? -> [GASSYSTEMS-741] NA62-CEDAR move to keller pressure sensor? - CERN Central Jira
GIF++ TGC gas system and return flow: [GASSYSTEMS-624] GIF++ TGC gas system return flow - CERN Central Jira
[GASSYSTEMS-674] MFCs to be checked - CERN Central Jira :
- Fondoscala del MFC di R134A e sensore umidità del gas RPC [GASSYSTEMS-645] Fondoscala del MFC di R134A e sensore umidità del gas RPC - CERN Central Jira
- Neutrino platform gas analysis: [GASSYSTEMS-622] RE: Analisi di outgassing di diversi materiali - CERN Central Jira
- ALICE T10 MFCs: [GASSYSTEMS-669] ALICE T10 TR: calibration MFC pour C4F10 - CERN Central Jira
- ND280 MFCs to check [GASSYSTEMS-679] ND280 MFCs to check - CERN Central Jira
non-LHC safety valve --> check lista di Fabio
[GASSYSTEMS-172] non-LHC safety valves to be verified - CERN Central Jira
ELOG - safety valves to be verified for non-LHC systems
Additional requests/projects/discussions
887 CEDAR new "mixers" --> [GASSYSTEMS-509] CEDAR for beam lines - CERN Central Jira
AMBER
EDMS leak test?
test certificate x-ray?
ATEX certificate?
who is technical coordinator
resource manager Oleg D?
no money? should we stop? and resume in 2026?
Commissioning when? -> TICKET
when they would like to start? Moritz? -> ask
LEAK DETECTORS LIST -> TICKET
MAINTENANCE INTERVENTIONS WORK ORDER FOR STATISTICS -> TICKET
PROJECT 2025
summary TICKET
examples of topics for the common discussions:
-cms id flushing -> Andrea
-cms r134a operation and spare -> Andrea
-cms cf4 operation and spare -> Andrea
-atl tgc nc5h12 -> Kacper
-Analysis boxes -> LPh
-C4F10 new recuperation installation -> Patrick
There are minutes attached to this event.
Show them.