EL3060 CONTINUOUS GAS ANALYZERS | OI/EL3060-EN REV. A 73Magnos206: Notes on calibrationCalibration methodsAutomatic calibration: Zero-point/end-point calibration or substitute gascalibration (set ex works if a substitute gas com-ponent is installed) or single-point calibrationManual calibration: Zero-point/end-point calibration or substitute gascalibration (set ex works if a substitute gas com-ponent is installed) or single-point calibrationSubstitute gas calibrationIf test gases are not available for calibration, e.g. because they cannot befilled in test gas cylinders or because their components are not compatiblewith each other, the analyzer can be set ex works as per the order for cali-bration with a substitute gas. In addition to the measuring range of thesample component, a measuring range for the substitute gas component isinstalled ex works; this is normally O 2 in N2. This setting is documented in theanalyzer data sheet (see page 33).The substitute gas calibration is a zero-point/end-point calibration of thesubstitute gas component. The zero and end points of measuring range ofthe sample component in the analyzer are then corrected by the values de-termined in this calibration.NOTESubstitute gas calibration must always be used to calibrate all (sample gasand substitute gas) components if the analyzer is set up for substitute gascalibration. Zero-point/end-point calibration either in the sample compo-nent or substitute gas measurement ranges leads to erroneous analyzercalibration.Single-point calibrationThe long-term sensitivity drift of the Magnos206 is less than 0.05 % vol. O 2per year. Thus only an offset correction needs to be routinely carried out inthe measuring ranges from 0–5 to 0–25 % vol. O 2. This so-called single-pointcalibration can be conducted at each point on the characteristic curve sincea parallel shift of the curve is effected. Depending on the measurement task,we also recommend that an end-point calibration is carried out at least oncea year.Note: The sensitivity drift can amount to 1 % of the measured value per weekin the short-term.Single-point calibration in measuring ranges with suppressed zeropointThe single-point calibration can also be carried out in a measuring rangewith a suppressed zero point, provided that the suppression ratio is lessthan 1:5. The O 2 concentration of the test gas must be within the measuringrange.Air pressure correctionThe current atmospheric pressure must be considered for the single-pointcalibration. This is carried out automatically if a pressure sensor (see page26) has been installed in the analyzer.
