Thermo Scientific AquaSensors
™
AnalogPlus
™
Contacting Conductivity Sensor User Guide
18
4.
CONDUCTIVITY SENSOR MAINTENANCE
4.1.
Cleaning the Contacting Conductivity Sensor Head
4.1.1.
In order to maintain an accurate measurement value, the sensor will need occasional maintenance.
The maintenance interval will be dictated by the process in which it is installed. The harsher the
process, the more often the sensor will require maintenance. Regular maintenance will yield a longer
sensor life.
4.1.2.
The sensor cleaning procedure is as follows:
4.1.2.1.
Remove sensor from service and rinse or spray it with warm water to remove heavy deposits.
4.1.2.2.
Soak the sensor in a container of hot detergent water for one hour. Do not use detergents that
contain oily skin softeners like aloe or lanolin that can coat the electrodes. Alconox
®
and Dawn™
dishwashing liquid work well.
4.1.2.3.
Use a soft-bristled brush, such as a soft toothbrush, and hot detergent water to scrub the entire
electrode end of the sensor.
4.1.2.4.
Rinse the electrode end with clean warm water.
4.1.2.5.
If deposits are still present on the electrode repeat steps 2 and 3. In the case of lime or other
mineral deposits a weak solution (about 0.1 M) of hydrochloric acid may be used. In some cases, a
dilute solution (about 10:1) of water and chlorine bleach or a solution of water and EDTA may also
work. Stubborn oil or grease deposits may require cleaning with a solvent such as acetone or
alcohol. Protein deposits may be cleaned with a pepsin-based cleaning solution. Bacterial or mold
growth may be removed with dilute chlorine bleach.
Caution:
Ensure that dangerous chemical reactions will not occur between process
deposits and cleaning solutions. Compounds of cyanide and hydrochloric acid will react
and pose health risks. Cyanide is often used in electroplating and in gold refining. If in
doubt about potential chemical reactions, check with a chemist before cleaning.
4.1.3.
Before returning the sensor to service, allow it to soak in water at ambient temperature for about an
hour to restabilize the Conductivity electrode.
4.1.4.
After cleaning the sensor, calibrate sensor per instructions in the Model C99 controller manual.
4.1.5.
Reinstall sensor in process.
