Servomex 4900 — Alarm Decision Trees

Legacy 4900 alarm archive. Match the nameplate, fitted channels and manual generation before applying these notes. These diagrams have not been validated as a current-generation 4900 Multigas service procedure.

Golden rule: Always stabilize sample flow, pressure, and moisture before touching calibration or sensors.
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Sample Flow Alarm

Flow below design limit or unstable (pressure hunting).

Sample Flow Alarm Process pressure available? Pressure hunting? Process issue → Inform OPS Check filters / moisture Restore flow; verify alarm status
The former numerical failure-frequency breakdown was unsupported and has been removed. Use configuration-matched diagnostics to establish the cause.

Oxygen Sensor Fault (Paramagnetic)

O₂ signal unstable or outside physical limits.

O₂ Sensor Fault Is sample flow stable? Zero gas truly O₂-free? Check moisture / drains Further diagnostics required
The former numerical failure-frequency breakdown was unsupported and has been removed. Use configuration-matched diagnostics to establish the cause.

Communication Alarm

Analyzer values not updating in DCS.

Communication Alarm Analyzer running locally? Installed interface verified? DCS mapping / quality bit Network / power issue
The former numerical failure-frequency breakdown was unsupported and has been removed. Use configuration-matched diagnostics to establish the cause.

Technical references

Updated against manufacturer documentation. Match the document to the installed model and options.

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