Mettler Toledo InPro 6850i Bedienungsanleitung Seite 34

34
Type A, 2-electrodes system, InPro 6800
InPro 6800 for medium and high oxygen concentra-
tions. Cathode and anode /reference. Anode and ref-
erence are united in a silver / silver chloride electrode.
The following equilibration reaction takes place at the
anode resp. reference:
Reaction: 4 Ag + 4 Cl
Measurement
liquid or gas
Type B, 3-electrodes, InPro 6850i
InPro 6850i for medium and high oxygen concentra-
tions. The reference corresponds the conventional sil-
ver /silver chloride anode. The anode is a platine
electrode and separated from the reference.
The following reaction takes place at the anode:
Reaction: 4 H
The reference is a silver /silver chloride electrode.
After polarization there is a stable equilibrium be-
tween electrode surface and electrolyte. No net-reac-
tion takes place.
Reference reaction in equilibrium:
Reaction: No current
Measurement
liquid or gas
Type C, 3-electrodes, InPro 6900(i)
InPro 6900 and InPro 6900i. For oxygen measure-
ments in the lower ppb range. Here, the anode and
reference are united in a silver /silver chloride elec-
trode (as with type A). The sensors are equipped with
InPro 6850i, 6900i, 6950i
52 206 349
InPro 6850i / 6900i / 6950i O
O
2
O
O + 4 e
2
O
2
O
–
→ 4 AgCl + 4 e
O
2
2
–
→ 2 O
2
O
2
2
© 02 / 09 Mettler-Toledo AG
Sensor 12 / 25 mm
2
–
Polarization
voltage
Reference / Anode
Cathode
Electrolyte
Glass insulator
NTC 22 k
Membrane
–
+ 4 OH
Polarization
voltage
Reference
Cathode
Anode
Electrolyte
Glass insulator
NTC 22 k
Membrane
Printed in Switzerland