Hach ORBISPHERE 32301 Manuel D'utilisation De Base page 9

1. Fill the sensor with standard ORBISPHERE model 2959GP electrolyte, then mount any
membrane and stand the sensor face down in boiling water for about ten minutes shifting its
position from time to time.
2. After boiling, allow the sensor to cool and then remove the membrane and rinse the sensor head
with water. The sensor head should now be free of grease.
4.3 Re-chloridization of the cathode
In this process a fresh layer of silver chloride is grown on the cathode surface.
1. Fix the sensor vertically onto a clamp or stand so that its head is facing upwards. If the sensor
has a permanently attached cable, introduce the LEMO plug into the sensor receptacle (No. 6 in
Figure 1 on page 5). Sensors with detachable cables may connect directly to the sensor cable
(No. 3).
2. For the supplied regeneration cell, push the tube of the regeneration cell over the sensor head
until it reaches a stop. Connect the red banana plug into the counter electrode socket (No. 7).
3. For the DG33619 regeneration cell, screw the regeneration cell in the sensor head. Connect the
blue banana plug into the counter electrode socket (No. 7).
4. Pour about 10 ml of standard ORBISPHERE model 29011 chloridizing solution into the
regeneration cell. This will cover the sensor head to a depth of about 1 cm. Eliminate any bubbles
of air by tapping the side of the cell.
5. Turn the selector knob (No. 4) to the chloridize position and press the TIMER switch (No. 5).
The warning light will come on and remain on for about eight minutes while re-chloridization takes
place. During this period the cathode will turn from silver-white to a pale pink color which will
gradually darken as the layer of silver chloride builds up.
6. With de-chloridization of the cathode complete, disconnect the counter electrode and sensor, and
empty the solution from the regeneration cell.
7. Rinse the interior of the regeneration cell and sensor with water.
8. Based on the model used, remove or unscrew the regeneration cell from the sensor and rinse the
sensor head again with water.
4.4 Activation of the anode
In this process the central electrode (anode) is polished, and then treated with concentrated nitric
acid.
Do not to put acid on the newly chloridized cathode.
1. Follow the sensor face polishing instructions described in the sensor operator manual supplied
with the sensor.
2. Install the membrane support, finger tight, using the sensor mounting tool. Make sure the smooth
side with a groove faces out when installed.
3. Fill the sensor reservoir with water. This helps protect the new silver chloride layer in case any
nitric acid leaks into the reservoir.
4. Place a drop at a time of concentrated (approximately 70% by weight) nitric acid on the center of
the anode. Allow the acid to spread to the surrounding guard electrode. It is recommended to
leave the acid on the anode for about 30 seconds.
5. Wash off the acid, and repeat the procedure (applying drops of nitric acid) two more times.
6. Wash the sensor thoroughly with distilled water.
C A U T I O N
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