Hach ORBISPHERE 32301 Basic User Manual page 11

Pin 3 and Pin 4
Pin 3 and Pin 9
Pin 3 and Pin 1
Pin 1 and Pin 4
Pin 1 and Pin 9
To check for continuity between each of the electrodes and the corresponding pin on the LEMO plug
it is necessary to empty the electrolyte reservoir then rinse it out and thoroughly dry it. In particular, it
is essential that the gap between the cathode (anode for hydrogen sensors) and the guard ring
electrode be absolutely dry.
By touching each of the electrode surfaces very carefully in turn with one ohmmeter lead and the
corresponding pin with the other, as follows:
• central electrode and pin 4
• outer electrode and pin 9
• guard electrode and pin 1
You should find a value of zero in each case. A discrepancy in any of the above checks suggests a
connection fault within the sensor and should be reported to your Hach Lange representative.
Be careful not to scratch the electrode surfaces.
Resistance tables
The following tables show the resistance between the sensor LEMO plug pins. All values are in kilo
ohms.
All sensors:
Sensor Model
31110 31120 31123 31130
31131 31140 31141 31230
31231 31240 31330 A1100 C1100
31331
A discrepancy greater than ±1% indicates a probable fault in the circuit.
Resistance should be infinite
A finite resistance can exist in these cases, but it must not be zero
Pins
3-6
2-5
7-8
C A U T I O N
0°C 10°C
351.0 207.9
351.0 207.9
20°C 25°C 30°C
126.7 100.0 79.4
126.7 100.0 79.4
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40°C
51.0
51.0