Emerson Process Management GmbH & Co. OHG
3-8
X-STREAM XE
Instruction Manual
HASXEE-IM-HS
10/2012
3.2 Oxygen Measurement
3.2.2 Electrochemical Measurement
This sensor utilizes the principle of galvanic
cells, fig. 3-5 shows the design.
For storage and handling instructions, and
safety data
Chapter 7 "Maintenance".
Fig. 3-5:
Electrochemical O
2
Sensor -
Design Principle
Fig. 3-6:
Electrochemical O
2
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 (eO
2
) 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 fluororesin
membrane. Oxygen which barely diffuses
through the membrane is electrochemically
reduced on the gold electrode.
The temperature compensating thermistor and
adjusting resistance are connected between
the cathode and anode. The current genera-
ted by oxygen reduction is converted into a
voltage by these resistances.
The value of the current flowing 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
Summary of Contents for Rosemount X-Stream Series
Page 535: ......
