G 1400 series
Measurement Basics | 5
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5.2.1
General Design Electrodes / Measuring cell
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There are basically two different types of measuring cells: 2-pole and 4-pole measuring
cells.
Control and/or evaluation take place in a similar manner; the 4-pole measuring cells
can compensate well for polarisation effects and contamination to a certain degree
with the more elaborate measuring processes.
2-pole measuring cell
4-pole measuring cell
The device series is equipped with a permanently connected 2-pole measuring cell.
5.2.2
Calibration / adjustment of the measuring cell
_
NOTE
In harsh applications and due to ageing processes, the cell constant of measuring cells
changes, which leads to incorrect measured values.
Depending on the application and precision requirement, the overall precision of the
display device and measuring cell measuring chain should be checked regularly.
Special testing and calibration solutions, such as GKL 100, 101 and 102 are available
for this purpose.
In normal application conditions, semi-annual testing is recommended
– please refer
to 4.2
“Adjustment of the measuring input“.
5.3
Total dissolved solids / TDS measurement
(only available at
G 1409 and G 1410)
The total dissolved solids measurement - TDS measurement - determines the total
dissolved solids, which also called evaporation residue, based on the conductivity and
a conversion factor CtdS of the total dissolved solids. Well-suited to conduct simple
concentration measurements of salt solutions. The display shows mg/l.
Display value TDS = conductivity [in µs/cm, with nLF = 25°C] * CtdS
