Endress+Hauser Oxymax COS22D, Operating Instructions Manual

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Function Oxymax COS22D
18
Hauser
5 Function
5.1 Measuring principle
5.1.1 Amperometric principle
The oxygen molecules diffused through the membrane are reduced to hydroxide ions (OH-) at the
cathode. Silver is oxidized to silver ions (Ag+) at the anode (this forms a silver halogenide layer).
A current flows due to the electron donation at the cathode and the electron acceptance at the anode.
Under constant conditions, this flow is proportional to the oxygen content of the medium.
This current is converted in the transmitter and indicated on the display as an oxygen concentration in
mg/l,
μ g/l, ppm, ppb or Vol%, as a saturation index in % SAT or as an oxygen partial pressure in hPa.
5.1.2 Sensor design
a0011869
Fig. 10: Exploded view
1
2
3
4 Plug-in head
Pressure ring
Sensor shaft
O-ring 8.5 x 1.5 mm 5
6
7 Membrane body
Shaft cover
Glass body with cathode and anode 8
9 Process sealing 10.77 x 2.62 mm
Process connection Pg 13.5