Glove Box Purifier Regeneration: Safe Forming-Gas Procedure & Fast Troubleshooting

When to Regenerate (Data-Driven)

• Dew point trend: faster rise or higher plateau under comparable workload.
• O₂ trend: slower return to baseline with no recent transfers.
• Discipline first: If antechamber SOP and leak rate are good yet metrics drift, regenerate.

5-Minute Safety Checklist

• Gas: Confirm ≤5% H₂/N₂ on cylinder label, regulator, and flow setpoint.
• Exhaust: Regeneration outlet connected and flowing to a safe vent.
• Interlocks: Heat–flow–O₂ logic armed; over-temp/under-flow alarms tested.
• No ignition sources; ESD grounded where required.
• Sensors healthy: O₂/dew-point reading and logging OK.

If you can’t verify exhaust or the mix is >5% H₂, do not regenerate.

Standard Procedure (follow your OEM setpoints)

1. Prep
   • Stop solvent work; optional low-temp bake of internals (40–60 °C) if materials allow.
   • Route valves to the regen loop; confirm bypass/isolations.
2. Copper Catalyst (O₂ bed) — Heat + Forming Gas
   • Set a stable low forming-gas flow; ramp temperature per OEM.
   • Watch temperature vs. time and O₂/dew-point trends; if heating runs away, reduce temp/flow immediately.
3. Molecular Sieve (H₂O bed) — Heat + Dry Purge
   • Heat per spec while sweeping with dry inert to remove moisture.
   • Hold for the recommended duration, then cool.
4. Cool-down & Return to Service
   • Step down to safe temperature; purge the regen loop with working gas.
   • Switch to circulation and observe stabilization for 2–4 h.

Acceptance & Records

• Targets: dew point ≤ –40 °C (stricter as needed), O₂ ≤ 1–5 ppm.
• Stability: trends flat within 24 h.
• Log: timestamps, flows, temps, alarms, interlock states, cylinder batch/lot, before/after plots, operator sign-off.

Troubleshooting (symptom → cause → fix)

• Over-temperature or hot spots → poor thermal contact / too much flow → lower temp/flow; check heater wrap & thermocouple placement.
• Still “wet/high O₂” after regen → media aged or solvent-poisoned → extend cycle; replace media if performance doesn’t recover.
• Noisy/oscillating readings → sensor in a dead zone / uncalibrated → sample main circulation; recalibrate.
• Slow return to baseline → transfer discipline lacking → enforce three vacuum cycles + equalization.
• Frequent nuisance alarms → interlock limits or valve logic off → review PLC/limits; verify valve positions.

Practical Notes

• Argon systems: You can regenerate with H₂/N₂—just isolate the regen loop and purge back to Ar before normal operation.
• Trend, don’t guess: Use a 7–14-day moving average of dew point/O₂ to schedule regen.
• Solvent load: Add cold/charcoal traps and keep lids on to meaningfully extend intervals.