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Emerson Process Management GmbH & Co. OHG3-8
X-STREAM XE
Instruction Manual
HASXEE-IM-HS
04/2010
3.2 Oxygen Measurement
3.2.2 Electrochemical Measurement (I)
This sensor utilizes the principle of galvanic
cells, g. 3-5 shows the design.
Fig. 3-5: Electrochemical Sensor -
Design Principle
Fig. 3-6: Electrochemical Sensor - Assembly
1 Anode (lead)
2 Cathode (Gold)
3 Electrolyte solution
4 Membrane
5 Thermistor
6 Resistance
7 Titanum wire
8 O-Ring
9 Pressure compensating volumes
10 Lid
11 Electrical connections
12 Lids
13 Current collector
12
9
8
4
10
1
6
5
7
3
11
2
12
11
13
The electrochemical oxygen sensor‘s key
components are a lead anode (1) and a gold
cathode (2) surrounded by a special acid
electrolyte (3).
The gold electrode is integrated solid with the
membrane,which is a non-porous uororesin
membrane. Oxygen which barely diffuses
through the membrane is electrochemically
reduced on the gold electrode.
The temperature compensating thermistor
and adjusting resistance are connected bet-
ween the cathode and anode. The current
generated by oxygen reduction is converted
into a voltage by these resistances.
The value of the current owing to the thermi-
stor and resistance varies in proportion to the
oxygen concentration of the measuring gases
which contact the membrane. Therefore, the
voltage at the terminal of the resistances is
used for the sensor output to measure the
oxygen concentration.
Sensor inserted
into holder