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32/1-A24 (CERN)
Gas R&D activities
Gas R&D activities 2026-09-24
Key Outcomes
The team completed the first total reflux operation of the distillation column, with binary exhaust analysis showing CO2 rising from 12% to 93%, indicating successful separation. However, several instrumentation and cooling anomalies were identified that prevent full validation of results. GC calibration was also corrected, significantly changing historical R134A absorption percentage calculations.
Completed
· Total reflux operation executed: feed loaded, reflux valve (PV 43) opened, closed-loop recirculation achieved.
· Binary exhaust analysis confirmed separation signal: CO2 increased from 12% → 93%; RM348 expected at column bottom.
· GC calibration completed for argon and isobutane matrices (SF6 and R134A); all prior pass-test R134A percentages recalculated.
· Desorption purity: >98% R134A; absorption: maximum 5.11%, mean 0.79% R134A during absorption phase.
Blockers
· Bottoms analyzer unreachable: heater capped at 30°C (default limit); no vapor generated from reboiler bottoms sample point, preventing RM348 purity confirmation.
· Reboiler level/temperature conflict: DPT reads ~65% liquid level, but temperature and pressure conditions indicate no liquid should be present — either the level sensor or temperature sensor is incorrect.
· Coolant bypass suspected: cooling line temperatures remained at ambient even after coolant passed through reboiler; top condenser reached –24°C but reboiler sensors did not respond, suggesting coolant is bypassing the reboiler.
· Analysis point location issue: bottoms sample valve is near the base of the buffer; with atmospheric outlet via rotameter, generating vapor flow is difficult.
Decisions Made
· Raise heater temperature limit above 30°C: requires change from both the device and the barrier/vertex cabinet.
· Add temperature sensor to cooling return line (Armaflex cut method, as done in LACB) to confirm whether coolant is actually circulating through the reboiler.
· Partially close hand valve on the main coolant path to create impedance and force flow through the reboiler section.
· GC calibration method corrected: area ratio must account for argon baseline; prior calculations used only isobutane ratio, inflating R134A percentages.
Open Questions
· Actual R134a purity at reboiler bottom still unknown pending valid analyzer sample.
· Whether the 65% DPT reading reflects real liquid accumulation or a sensor artifact (offset was 0% at start, so no known initial error).
· Whether coolant flow is insufficient due to high impedance in the circuit or an actual bypass path.
· Display of raw millibar pressure readings from DPT sensors requested to cross-validate level calculation.
Action Items
· Thomas/Emmanuel: Increase heater temperature limit above 30°C from both device and cabinet settings — retry bottoms vapor sampling.
· Davide: Install temperature sensor on cooling return line (cut Armaflex) to confirm coolant circulation status.
· Emmanuel/Maria Cristina: Partially close hand valve on coolant bypass path to redirect flow through reboiler; monitor Lauda chiller response.
· Thomas: Add DPT millibar pressure display to control view for level sensor cross-verification.
· Emmanuel/Maria Cristina: Recheck bottoms analysis — attempt sampling this afternoon with pressure in buffer confirmed at ~1.5 bar.
Gas R&D activities 2026-09-17
Action Items
· Emmanuel: Add slide on pressure sensor and Zimmerli/Bronkhorst comparison for future reference.
· Max: Check Fe-55 source activity/decay rate — assess if a second source is needed before Run 4; contact radioprotection if new purchase required.
· Ryan/Emmanuel: Investigate why CMS experimental temperature (~–50°C) diverged from simulation prediction at 30% CO2.
· MOF simulation lead: Begin kinematic/molecular dynamics study; include CO2 and H2O molecules in future simulation runs.
· Max: Check which 2017 gas measurement data is available vs. missing; confirm gas inventory in the gas room.
· Ryan/Emmanuel: Look into binary interaction parameters for R1224YD + isobutane for potential distillation simulation.
Gas R&D activities 2026-09-03
Action Items
· Team (today): Check Atlas circuit for existing refrigerant with Fabio; verify chiller operation.
· Emmanuel Ryan + team (tomorrow if available): Fill distillation column and observe liquid formation.
· Simulation team: Test 1.5 bar operating point; assess whether a compressor upstream is needed.
· Bjorn: Subtract noise from detector fit; retry alignment with cleaner signal.
· Max: Swap strip profile in frame C; confirm impedance fix for detector 32.
· Albin: Add CF3I and C4F10 molecules to the simulation table.
· Max: Finalize plots for ECOGAS contribution from May test beam and ZD scan results.
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