Endress+Hauser Turbimax CUE21, Руководство по эксплуатации

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Turbimax CUE21 / CUE22 Operation
Hauser 23
8.2 Instrument calibration
The device was calibrated and tested prior to leaving the factory. Therefore, it is possible to
use it directly out of the box. Under normal conditions, recalibration is recommended at
least once every three months.
1)
Types of calibration
• Complete three-point calibration
This calibration is used if accuracy is required across the entire measuring range of the
device, from 0.02 to 1000 NTU (CUE21) or 0.02 to 100 NTU (CUE22). If accuracy is
required only in the range below 10.0 NTU, e.g. for drinking water, calibration may also
be performed using only a 10.0 NTU and 0.02 NTU calibration standard.
• Offset
This method of calibration can be used if accuracy is required only in the immediate
vicinity of the turbidity value of the sample.
• The relay contacts remain in the last valid condition while the device is in
calibration mode.
• The device has a timeout function which causes it to revert automatically to AUTO
mode after 15 minutes of inactivity.
• During calibration, the fan located inside the device is switched off in order to
extend the service life of the desiccant. The fan is switched on during calibration
countdowns and after the device returns to AUTO mode or after five minutes
(whichever comes first). It is recommended that the measurement chamber be kept
covered during calibration and that the flow-through cuvette be inserted
immediately after calibration to prevent premature saturation of the desiccant.
8.2.1 Calibrations standards
To achieve the specified level of accuracy across the entire measuring range of the device,
we recommend the following calibration standards:
• 0.02 NTU
• 10.0 NTU
• 1000 NTU (CUE21)
100 NTU (CUE22)
These calibrations standards are more stable than formazin and have a shelf life of 12
months. Prior to calibration, verify the expiry dates to ensure that these calibration
standards have not expired. If you are using formazin to calibrate the device, ensure that a
fresh formazin stock solution is used so that the specified accuracy is achieved.
A a shelf life of 12 months is guaranteed for the 10.0 NTU calibration standard only if
it is stored in the plastic bottle. Once it is transferred to a glass cuvette, it must be
used for calibration immediately and then disposed of.
8.2.2 Indexing cuvettes
To achieve the highest possible level of accuracy and to allow for normal scratches and
signs of wear and tear on the cuvette glass when calibrating, we recommend that the
cuvettes be indexed. Calibration standards and standard kits purchased from Endress
+Hauser are supplied with indexing rings
The following steps allow repeatable indexing of calibration standards:
1. Shut off the flow using the shutoff clamp provided.
2. Remove the flow assembly with the flow-through cuvette.
3. Insert the calibration standard while the device is in AUTO mode.
1) The EPA recommends that online turbidimeters be calibrated using a calibration standard at least once every three months if they are used for
EPA reporting.
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