DA 7440 User Manual v.1.1 Aug 2015
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8. Maintenance
8.1 DA 7440 Maintenance overview
Technical maintenance
The DA 7440 instrument is designed robust and to require a minimum of regular maintenance in
the demanding plant environment. The instrument has an internal optical reference and Xenon
light system for continuous ensuring of instrument performance. If instrument errors occur are
notifications shown in the process Plus interface. Error messages are available on external
communication interface.
Measurement accuracy
The NIR technique is empirical and product specific calibrations are needed for measurements.
Adjustments and validations of the DA 7440 measurements are done through sample collection
in close vicinity to the sensor. Collected samples should be analysed by wet chemistry analysis.
The collected samples should cover the expected chemical range and production types on which
measurements are to be made in the measurement position. In case production is made on
sample varieties or contents that are not well represented in the calibrations could the calibrations
be updated also to measure accurately on these products.
In accordance with international standards and good practice are the requirements on number of
samples collected the following:
>10 samples should be collected in order to make a measurement adjustment.
>20 samples should be collected in order to validate the measurements.
>50 samples should be collected in order to update measurement calibrations
In order to continuously ensure measurement performance it is recommended to collect grab
samples on regular bases, to compare DA 7440 measurement results with laboratory results.
8.2 Maintenance checklist
Summarized steps for maintenance are shown below. These steps should be checked weekly.
Weekly maintenance check
1. Check Instrument status in Process Plus interface. Instrument should be in state Running
with no Error messages shown. Further info Chapter 10.1
2. Check the instrument measurement positioning.
3. Check that the instrument is supplied with clean compressed air to supply its air-purge.
4. Check that the instrument measurement window is clean. Further info in Chapter 8.3
Extended check
5. Measure and store external Check sample
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