Hach ORBISPHERE 32301, Basic User Manual

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9. Turn the selector switch to anode and press the TIMER switch. Here the bubbles may be more
reluctant to appear and you may need to press the TIMER switch several times before you are
satisfied that the anode is clean enough, particularly for ozone sensors.
10. Important: If cleaning an A1100 or C1100 sensor, skip this step and continue at Step 10 . If after
five cleaning periods bubbles do not appear then pour out the cleaning liquid, remove the
regeneration cell, and carry out a chemical cleaning of the sensor as described in the sensor
manual. Complete the cleaning with the 32301 unit by going back to
Step 3 above.
11. Once the three electrodes are clean, disconnect the counter electrode and sensor and empty the
cleaning solution from the regeneration cell.
12. Rinse the interior of the regeneration cell and sensor with water.
13. Based on the model used, remove or unscrew the regeneration cell from the sensor head and
again rinse both well with water.
14. Visually inspect the three electrodes. They should appear clean and of a uniform color. If there
are any dark patches, particularly on the anode, repeat this cleaning process until any such
patches disappear.
Figure 4 Orbisphere DG33620 EC cleaning sensor support
Replace the membrane
Once cleaning is complete prepare the sensor for reuse.
1. Important: If cleaning an A1100 or C1100 sensor, skip this step and continue at Step 2 . Follow
the sensor face polishing instructions described in the sensor operator manual supplied with the
sensor.
2. Install a new membrane and electrolyte to the sensor. Refer to the operator manual delivered with
the sensor for details on how to do this as the procedure is different depending on the type of
sensor.
3. Rinse excess electrolyte off the sensor with water.
4. The sensor can now be calibrated and returned to service.
Hydrogen sensor servicing
A hydrogen sensor service consists of the following operations:
1. De-chloridization of the cathode. This process removes the chloride film from the silver cathode
surface.
2. De-greasing the sensor. This is only necessary under certain, fairly unusual circumstances.
3. Re-chloridization of the cathode. Here a fresh layer of silver chloride is grown on the cathode
surface.
4. Activation of the anode. The anode surface is polished and treated with concentrated nitric acid.
5. Electrolyte and membrane replacement.
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