The reference condition of the dew point must be traceable to the appropriate standards. The user adjustment requires a stable humidity generator capable of producing the required humidities and a calibrated reference dew point meter. For adjustment, the probe and the reference dew point meter are connected to the humidity generator output, the reference condition is adjusted and let to stabilize. After the probe and the reference dew point meter are stabilized, the DM70 reading is adjusted to correspond the reference value.
For the adjustment of the DMP74A probe, the dew point reference temperature should be between –40 °C and –60 °C (–40 °F ... –76 °F), and for the DMP74B and DMP74C probes, the dew point reference temperature should be between –57 °C and –67 °C (–70.6 °F ... –88.6 °F). The optional sampling cell DSC74 (see Figure 1) can be used as a calibration chamber to be connected with a humidity generator.
To ensure the correctness of the adjustment, the reference dew point meter must be calibrated at a recognized laboratory with a known uncertainty and traceability to national or international standards.
The Td and H2O parameters can be viewed in the adjustment mode to see the effect of the adjustment.
To see when the adjustment was made last, select Last adjustment date or check the date from the Device information view (see Device information).