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Gas systems weekly project meeting
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32/1-A24 (CERN)
gas systems project meeting
Gas systems
Gas systems 2026-08-27 09:00(GMT+2:00)
Key Outcomes
Multiple concurrent gas system issues were reviewed across ALICE, ATLAS, CMS, and LHCb detectors. The RPC circulation pumps (Pump 2 failed, Pump 3 active) and RPC Rack 70 valve problems are the two most critical open items.
For CLOUD Zone access remains restricted until at least the 21st, limiting on-site intervention. A target run start of September was noted but may be postponed.
Incidents Resolved
· CSC input valve, Rack 61: Chambers were disconnected without notification; gas flowed through bubbler supply, pump pressure dropped, regulation valve closed at −3.5, causing rack stop — root cause identified as miscommunication, not equipment failure.
· RICH1 distillation cooling circuit: Misassignment of temperature sign caused failure; corrected and resolved.
· 904 Mass Flow Controller: Confirmed complete.
· CSC panel: Work finished; glass rotameter replacement pending; ticket closed with final cost logged; TID to be completed.
· RPC circulation pump issue: Running on Pump 1 exceeded 3,000 hours; Pump 2 failed (pressure dropped); Pump 3 activated but showed uneven membrane pressure. Opening and resealing the membrane depressurized it and restored operation — currently stable on Pump 3 for 2–3 days.
Active Issues
RPC Purifier 2
· Pump not reaching vacuum; purifier stopped last week.
· Disassembly and repair planned for current/next day; experiment confirmed oxygen increase is acceptable short-term.
RPC Circulation pump 2
· Membrane pressure concern: All membranes showing slowly rising inter-membrane pressure since July despite no maintenance changes since January; non-return valve (metallic, not 100% tight) suspected as backflow source.
· non-return valve last changed in 2024 (two years old); replacement under consideration.
Rack 70 RPC — CMS
· Problem 1: Output ECONEX valve causing pressure perturbations; temporarily forced to 30% — motor/electronics suspected, replacement likely needed.
· Problem 2: Input pressure increased after chamber repair by Alexander; unclear whether cause is the repair or a dirty manifold/supply.
· Manifold cleaning proposed to isolate root cause; if pressure normalizes, same issue may exist in other racks.
· Ticket opened with Maria Christina; intervention tentatively planned for mid-September.
· Two problems treated separately: valve electronics issue is independent of the pressure increase.
Status Updates by Experiment
· ALICE TPC: Switched from Neon to CO2 injection (change made without notification during holiday); Neon still present in volume.
· ATLAS RPC purifier: Stopped; restart targeted for Monday at earliest.
· Analysis chain: Action to review which detectors are active and whether monitoring table remains valid.
· NA62 CEDAR detector: Maintained at 100 mbar nitrogen pressure; straw system running.
· LHCb UT pressure regulation: Handle of Tescom regulation faulty; jira ticket submitted; Team to be informed next week. 15Need to check logic: When system stops manually, flow stops — unclear if this is intended behavior; on automatic power cut, system should switch to dry air. Action: Add exercise/drill to action list to test switchover scenarios (N2 → dry air, manual vs. automatic stop)
DSS Alarm Phone Call Issue
· Control room (2231) sends generic DSS alarm calls without specifying which experiment — recipient cannot determine relevance.
· Action: Identify and contact the person responsible for the alarm configuration to add experiment identification.
Access & Planning
· CLOUD: Zone access closed until 21st; scaffolding removal and large instrument installation scheduled for two consecutive Mondays.
· Mixer for Florian (LHCb/RICH): In planning;
· second mixer (recirculation electrical) awaiting Jonathan's return (back this week).
· Workshop week planning: FSU Team not fully present; ATLAS work (humidifier dismounting deferred, other Atlas work ongoing) is the priority; RPC In62 deferred to next week (half-day effort).
Action Items
· Davide: Complete RPC purifier pump disassembly and repair today/tomorrow.
· Andrea: Send CSC panel ticket link via WhatsApp; complete TID with final cost.
· Andrea + Maria Christina: Plan Rack 70 intervention (valve replacement + manifold cleaning) for mid-September.
· Patrick: Inform LHCb about UT pressure regulation handle issue next week.
· Patrick: Add LHCb-UT gas system stop/switchover behaviour check to action list.
· Louis-Philippe: Identify DSS alarm contact at control room and request experiment-specific identification.
· Team: Review LHC analysis chain detector activity table for relevance.
· Davide: Monitor ATLAS-RPC Pump 3 membrane pressure; evaluate gasket replacement.
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
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