During the operation of a natural gas analyzer, abnormal peak shape and response drift are two typical types of faults, and their diagnosis and elimination need to be systematically analyzed based on specific phenomena and equipment principles.

Abnormal peak shape: the cause and repair of the transition from tailing peak to bimodal peak

Tail peak: often caused by the adsorption of active samples by the injector liner or chromatographic column. Replace the liner or cut 1-2 circles at the front end of the chromatographic column for reinstallation; If the temperature of the column or injector is too low, it is necessary to raise the temperature to a reasonable range (the injector temperature should be 25 ℃ higher than the highest boiling point of the sample).

Forward peak (tongue peak): commonly seen in column overload or sample condensation. The injection volume can be reduced, or the injection port and column temperature can be checked, and if necessary, the temperature can be raised to eliminate condensation.

Double peak: often caused by sample co elution or improper installation of chromatographic columns. Sensitivity and injection volume need to be optimized, and the temperature should be lowered by 10-20 ℃ to separate peaks, or the chromatographic column should be reinstalled.

Dome shaped broad peak: may be caused by sample volume exceeding column capacity or low vaporization temperature. Reduce the sample size or increase the vaporization temperature to a reasonable range.

Response Drift: Systematic Investigation from Baseline Instability to Retention Time Fluctuations

Baseline irregularity or drift: Column loss or contamination is the main cause. Replace the liner or cut the front end of the chromatographic column, and clean the detector and injector.

Retention time drift: Temperature or gas flow rate changes are common triggers. It is necessary to check the column temperature box and the speed of the carrier gas line to ensure stable temperature and no leakage in the gas path.

Reduced response value: may be due to detector contamination or decreased sensitivity. The detector needs to be cleaned or contaminated chromatography columns and liners need to be replaced.