ELMETRON CX-401, User Manual

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User‘s manual for CX-401 multifunction meter v6.0x
14. MAINTENANCE OF THE CONDUCTIVITY CELL
The recommended conductivity cell with a range 0 ÷ 500 mS/cm is sufficient
for measurements in almost every type of liquids in maximal concentration.
Metal electrodes are easy to clean and plastic body ensures higher durability.
In case of using platinum cells the electrodes must not be cleaned
mechanically, because it results in rubbing off the platinum layer, what can
cause decreasing of accuracy, lowering of stability and changing of the
K constant. Measurements of liquids with oils and heavy sediment content
may cause platinum contamination, make the measurement impossible and
irreparably damage the electrodes.
To obtain stable readings it is advisable to soak the cell for an hour before
the measurement. It is especially important in case of measurements in
distilled water.
Maintenance of the cell consists in accurate rinsing the measuring cell with
distilled water.
In case of fat content in the measured liquids it is possible to clean the
electrodes by immersing the cell in acetone, chloroform, tetrahydrofuran or
detergent.
Broken glass cell cannot be used due to significant K constant change,
unstable readings and increase of the dependence of the result on the
position of the cell in the measuring vessel. To obtain correct measurement
results, the cell should be immersed in such a way for the solution to fill it up
and not to include any air bubbles. The best way is to immerse the cell, make
a few vertical moves and thus to remove air bubbles through holes in the
upper part of the cell. If the air bubbles are difficult to remove, it is advisable
to immerse the cell in a water – washing up liquid mixture, what lowers the
surface tension and disables air bubbles to stick to the surface of the cell
walls or electrodes. Next, wash the cell accurately with distilled water.