Mettler Toledo InPro Serie Instructions D'utilisation page 34

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34 
Measurement
liquid or gas
Type C, 3-electrodes, InPro 6900(i)
InPro 6900 and InPro 6900 i. For oxygen mea-
surements in the lower ppb range. Here, the anode 
and reference are united in a silver / silver chloride 
electrode (as with type A). The sensors are equipped 
with an additional guard ring around the cathode. 
Like the cathode with the anode, this forms a closed 
electric circuit, which prevents that oxygen diffuses 
from the side to the cathode and falsifies the mea-
surement result.
Measurement
liquid or gas
In all sensors the function of the cathode is identical. 
Between cathode and reference a constant voltage 
of – 500 resp. – 675 mV (polarization voltage) is 
applied. Thereby a reduction of O
cathode takes place.
Cathode:  O
and 
Anode: 
and  
The total equation thus is:
O
+ 2 e
2 
   
  H
$
2
InPro 6850 i / 6900 i / 6950 i 
52 206 349 
InPro 6850 i / 6900 i / 6950 i O
O
2
O
2
 + 2 e
2
H
O
 + 2 e
2
2
4 Ag  
$
+
4 Ag
 + 4 Cl
 + 2 H
O + 4 Ag  
2
O
 + 2 e
 + 4 Ag
2
O
2
O
2
O
2
O
2
 + 2 H
O  
$
2
  
  2 OH
$
  4 Ag
+
 + 4 e
  
  4 AgCl
$
  H
O
 + 2 OH
$
2
2
+
 + 4 Cl
  
© 04 / 13 Mettler-Toledo AG
 Sensor 12 / 25 mm
2
Polarization
voltage
Reference
Cathode
Anode
Electrolyte
Glass insulator
NTC 22 k
Membrane
Polarization
voltage
Reference / Anode
Cathode
Guard
Electrolyte
Glass insulator
NTC 22 k
Membrane
 into OH
 at the 
2
  H
O
 + 2 OH
2
2
 + 4 Ag
  4 AgCl + 2 OH
$
Printed in Switzerland
+
 + 4 e

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Ce manuel est également adapté pour:

Inpro 6850iInpro 6900iInpro 6950i

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