24
Operation
5.1.2 Calibrating
The instrument can save one turbidity curve and up to four solids calibration curves. This
makes measurements in media with different qualities possible. Each measurement point
can have one of the saved calibration curves assigned to it individually.
1-point calibration
In order to define a calibration curve, it is generally sufficient to use a single calibration
point in the probe's measuring range. This should lie in the upper third of the expected
measuring range.
Note: If the measurement value is below or above the range defined by a point, the instrument
displays an error message: Calibration insufficient +/-. This means an additional calibration point is
required.
Multiple-point calibration
For broad measuring ranges, a second calibration point must be recorded:
• First calibration point (lower value) at as low a concentration as possible.
• Second calibration point (upper value) at as high a concentration as possible.
Up to three calibration points per curve can be recorded. To record several calibration
points, the sample is diluted or sedimented. Recorded calibration points are indicated by a
star (e.g.
*
point 1) and remain saved even if the device is switched off in the meantime.
1. Fill a black container with a representative sample of the measuring medium.
Ensure that it is mixed evenly.
2. Use a part of the sample for the solids analysis in the laboratory.
3. Clean the probe.
4. Dip the probe into the container.
5. Select
MENU, confirm with ENTER/ON.
6. Select
CALIBRATE, confirm with ENTER/ON.
The instrument reads the probe data and info text appears on the display.
7. Select the curve shown and confirm with ENTER/ON.
8. Select the desired curve and confirm with
ENTER/ON.
9. Select
MEMORY and confirm with ENTER/ON.
10. Select
POINT… (Point 1, 2 or 3), confirm with ENTER/ON. In doing so, stir the
measuring medium with the probe.
The distance between the probe head and the walls and base of the container must
always be more than 70 mm (2.76 in.) (
Figure 9).
It takes 5 to 20 seconds to record the calibration point; then the selection menu for
calibration appears. While recording, "Memory" is indicated on the display.
11. Take the probe out of the container and clean it. If necessary, record more calibration
points with diluted or settled samples. Remove part of these samples for the solids
analysis in the laboratory.
12. Determine the solids content of the sample(s) in the laboratory.
13. Select
*POINT… (*Point 1, 2 or 3) and confirm with ENTER/ON.
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