Hach ORBISPHERE 31 Série Manuel D'utilisation Simplifié page 17

1. Place the sensor in a vertical position on its
base.
2. Fill the electrolyte reservoir with a few drops
of water, just enough to cover the outer
electrode. The center electrode must be kept
dry.
3. Place a drop of nitric acid on the center
electrode, covering only the electrode and
guard ring. Avoid spilling acid into the water.
Wait less than a minute, then rinse
thoroughly under tap water.
Nitric acid is dangerous! Please refer to the safety information from your chemical supplier.
6.4 Hydrogen sensor cell cleaning
Conditions
The hydrogen analyzer works on the principle that hydrogen molecules, passing through the
membrane, generate an electric current at the platinum anode surface. For this to take place, an
extremely clean metal surface is essential. If any film, grease or other impurity covers the platinum
surface, the reaction is impeded and may even be stopped.
In addition, the chemical reaction that takes place on the chloridized silver cathode leads to loss of
performance after a certain operation time.
As a result, a sensor service must be carried out to restore its original performance.
Method
The procedure for cleaning the H
32301 Sensor Cleaning and Regeneration Center. This procedure is explained in detail in the
32301 Operator's Manual.
As an overview, H electrochemical sensor cleaning consists of the following sequence of operations:
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• Dechloridization of the cathode: This process removes the chloride film from the silver cathode
surface (carried out by the ORBISPHERE 32301).
• Rechloridization of the cathode: A layer of silver chloride is grown on the cathode's surface
(carried out by the ORBISPHERE 32301).
• Activation of the platinum anode: The center anode surface is polished, and treated with nitric acid.
C A U T I O N
electrochemical sensor requires the use of the ORBISPHERE
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