Siemens MAXUM Edition II
Industrial process gas chromatograph used in refineries, petrochemical plants, and gas processing units. Focus on sampling stability, carrier gas integrity, oven control, valve timing, detector performance, and DCS communication.
Technician rule:
MAXUM performance depends heavily on carrier gas quality and
sample conditioning. Most repeatability and drift issues originate upstream.
Working Principle
The MAXUM separates process gas components in chromatographic columns and detects them using detectors such as TCD or FID. Precise oven temperature and valve timing ensure repeatable retention times.
- Sample injection through timed valve sequences
- Component separation in temperature-controlled columns
- Peak detection and calculation using calibration factors
Main Components
- Sample conditioning: filters, regulators, heat tracing, drains
- Carrier gas system: carrier source, regulators, purification traps
- Valves & loops: injection and switching valves
- Oven: heater, sensors, and controller
- Columns: analytical and backflush columns
- Detectors: TCD, FID, electronics
- Controller & comms: MAXUM controller, I/O, network
Calibration Procedure
1) Confirm analyzer is stable with no active sample or carrier alarms.
2) Verify carrier and sample pressures are steady (no hunting).
3) Run certified calibration gas for multiple repeatable cycles.
4) Update response factors and save method configuration.
5) Run validation gas and confirm results within limits.
6) Return to process and verify DCS mapping, scaling, and quality bits.
Major Troubleshooting Areas
- Poor repeatability: valve timing, pressure instability, moisture
- Retention time drift: oven temperature or carrier flow changes
- Missing / low peaks: valve leaks, restrictions, detector issues
- DCS issues: communication faults, bad scaling, quality bit errors