Culligan MP97 Manual page 43

ELECTROCHEMICAL SETTINGS
Better performance, in terms of precision, can be obtained from the µP97 by carrying out electrochemical settings
(in this way the errors introduced by the connection cable from cell to instrument and mechanical error from the cell
constant can also be compensated). If thermocompensation is required, the NTC10K must be immersed in the
buffer solution in order to take on its temperature.
1. Leave the measurement cell in the air.
Press the key [ CAL ]  <<CAL>> appears on the display.
2.
3. Press the key [ - ].
4. The µP 97 displays a flashing zero.
5. Press the key [ + ] to increase the setting.
6. Press the key [ - ] to decrease the setting (it is not usual to modify the zero value with the cell in the air.
7a. Press the key [ CAL ] to confirm the new setting.
7b. Press the key [ NEXT ] to retain the preceding setting in the memory.
8. Immerse the cell in a liquid whose conductivity is known (normally KCl (potassium chloride) is used - see
the following table).
Press the key [ CAL ]  <<CAL>> appears on the display.
9.
10. Press the key [ + ].
11. The µP 97 displays the previous value, flashing.
12. Press the key [ + ] to increase the setting.
13. Press the key [ - ] to decrease the setting.
14a. Press the key [ CAL ] to confirm the new setting.
14b. Press the key [ NEXT ] to retain the previous setting in memory.
If an attempt is made to calibrate the offset with values that are too distant from the start scale value, the µP 97 will
automatically reject the setting. The same happens if an attempt is made to calibrate the gain with an input signal
which is too low. If the µP 97 settings are forced with offset/gain values too distant from the standard, the following
errors are emitted:
ERR 17 MINIMUM OFFSET LIMIT REACHED
ERR 18 MAXIMUM OFFSET LIMIT REACHED
ERR 19 MINIMUM GAIN LIMIT REACHED
ERR 20 MAXIMUM GAIN LIMIT REACHED
M003-23 - Rev. 03 - 05/2009
Temp. KCl 1 n
(°C) (µS)
0 65410
5 74140
10 83190
15 92540
16 94430
17 96330
18 98240
19 100160
20 102090
21 104020
22 105940
23 107890
24 109840
25 111800
26 113770
27 115740
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Microprocessore µP97
KCl 0.1 n KCl 0.01 n
(µS) (µS)
7150 776
8220 896
9330 1020
10480 1147
10720 1173
10950 1199
11190 1225
11430 1251
11670 1278
11910 1305
12150 1332
12390 1359
12640 1386
12880 1413
13130 1441
13370 1468
13620 1496
13870 1524
14120 1552
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