Preparing The Cell - Xylem WTW Turb 750 IR Operating Manual

®
Turb 750 IR/T
ba77233e05 06/2023
The quality of the measured values depends on the optimum preparation of
the cell and sample.
 Preparing the cell (see section 4.5.1)
– Determine a suitable position in the cell shaft
– Marking a cell
 Preparing the sample (see section 4.5.2)

4.5.1 Preparing the cell

Even completely clean quality cells exhibit tiny differences in their light trans-
mittance, e.g. inhomogeneities of the glass or small defects (e.g. scratches).
Therefore, guidelines for accurate and reproducible measurements (e.g. US
EPA) recommend that you always align the cell in the same way for measur-
ing with the aid of arrows printed on or markings. This refers to sample cells
and cells for calibration standards.
Prior to using a cell for the first time, the suitable position of the cell in the cell
shaft is determined and marked to make sure the optical path is not dis-
turbed. For the following measurements, the cell marking can just be aligned
with the meter marking.
The cell marking should be checked regularly and renewed as necessary.
The cell can be used until no suitable position for the optical path can be
found.
We recommend that you do not treat any scratches in the cell
with oily liquids (not even with so-called "special silicone oils").
They could unnecessarily soil the meter and your working envi-
ronment. The optimum measurement accuracy is ensured by
aligning the cells. Scratched cells have to be replaced.
1 Clean the cell (see section 5.2.2).
2 Stick the label for the marking onto the cell cap.
3 Fill the cell with a homogeneous solution (e.g. calibration standard
10.0 NTU).
4 Insert the cell (see section 4.4).
Operation
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