DewPro MMR101 User’s Manual
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Chapter 5. Maintenance
Chapter 5. Maintenance
5.1
Cleaning
Particulate substances in the process gas may clog the protective filter. This may impair the function of the sensor.
Remove the filter and clean with a strong (halogen-free) solvent or by flushing with oil- and dust-free, dry air.
In the case of processes with a high concentration of finely distributed particles, additional filtering may be required
to prevent clogging of the sintered protective filter.
Make sure that the filter does not contain any solvent residue before screwing it back onto the sensor.
The sensor element must always be handled very carefully. If soiled, it may be briefly swished in a solvent (pure
hexing, toluene or acetone).
After cleaning the sensor with solvent, allow sufficient time for it to dry before reinstalling it.
5.2
Calibration
Factory Calibration
Fifty-five calibration values covering the entire measuring range are determined at the factory. NIST-certified
reference instruments are used for calibration (NIST = National Institute for Standardization Technology). The
calibration certificate supplied with the sensor confirms that the sensor matches the reference values.
Recalibrations
Just like moisture measurement, the recalibration cycle greatly depends on the operating conditions
(contamination, aggressive media, etc.) and sensor stress. Under normal process conditions, the sensor check /
recalibration should be performed after one to two years.
This cycle may be longer or shorter depending on operating conditions and accuracy requirements.
Field Validation
The user can perform a sensor check in the field. This validation takes place at room temperature (approx. 25
o
C)
using saturated salt solutions. It is intended as a decision aid in determining whether or not recalibration or sensor
replacement is required.
This check should be performed using an GE Sensing test unit with saturated salt solutions of 11.3 and 75.4% relative
humidity that can be ordered from the factory.
5.3
Repairs
Repairs must be carried out directly by the manufacturer or by the GE Sensing Service Engineer.
