Operation
Turb 430 IR/T
18
ba75507d09
08/2021
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.
Determining a suit-
able position in the
cell shaft
Marking a cell
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 4.2).
5
Press and keep the
<START/ENTER>
key depressed.
Turn the cell slowly and check the measured value:
– The measured value at the position should be no maximum.
– At the directly neighboring positions there should not be any
sudden changes of the measured values. The deviations of
measured values at the neighboring positions should not ex-
ceed the following values:
Measured value < 1 NTU: max. +/- 0.02 NTU
Measured value > 1 NTU: max. +/- 2 %
6
Release the
<START/ENTER>
key.
Measurement starts. The measured value is displayed.
7
Mark the determined position (aligning) of the cell on the label.
The cell is now prepared for all following measuring and calibration
actions.
