Preventive Maintenance - B&C CL 7685 Operator's Manual

B&C Electronics

9 PREVENTIVE MAINTENANCE

Controller
Quality components are used to give the controller a high reliability.
The frequency of such maintenance depends on the nature of each particular application.
As in any electronic equipment, the mechanical components, such as switches, relays and connectors,
are the most subject to damage.
Sensor
The state of the Platinum surfaces is critical for the normal operation of the system and should be
inspected during the recalibration, if deviations of more than 0.2 mg/l as compared to DPD are
detected.
Suggested methods for cleaning the electrode include chemical cleaning as following:
- remove the sensor from the cell,
- clean the Platinum rings by dipping the sensor for 30 seconds in a 5% HCl solution,
- rinse thoroughly the sensor into deionised or tap water,
- reinstall the sensor into the cell.
The above procedure does not remove the oxide from the Platinum, maintaining the regular measuring
conditions for an immediate calibration.
If necessary clean the Platinum rings by carefully wiping it with a soft tissue eventually soaked with
metal shining reagent.
Rinse carefully and re-install the sensor into the cell.
Allow the system to stabilize before calibrating.
The shining Platinum will have a sensitivity 2 times more than regular, so it is necessary to maintain
the sensor dipped into the water before calibrating.
This time is required for the new oxide layer generation on Platinum.
Operator's Manual - Rev. C - 05/05
CL 7685
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