Ph Calibration; Buffer Group - OHAUS ST400 Manual De Instrucciones

ST400 & ST400M Portable Meter
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3.3

pH Calibration

3.3.1

Buffer group

Meters can perform 1-5 point calibrations.

The purpose of the calibration is to convert the corresponding electrical signal (mV value) of
the pH electrode to a pH value. As the electrode storage time becomes longer or the
electrode being constantly used, the electrical signal of the same electrode in the same
sample (such as standard buffer) will be different, so regular calibrations are required.

Calibrate the pH electrode for the first use or after a period of time.
There are 6 buffer groups built-in the meter, you can select the buffer group in the pH setting→
buffer group, default buffer group is [OH US] (US standard), and the buffer value will be
automatically recognized during calibration.
The 6 predefined buffer groups are (at 25° C):
1 1.68
2 2.00
3 2.00
4 1.680
5 1.09
6 1.680
For example, after the sixth group is selected, the meter uses the data in the following table to
calibrate the actual value of the buffer corresponding to the real-time temperature during
calibration at 0.01 pH accuracy. E.g. a pH 9.18 buffer solution is calibrated at 20 ° C. The
instrument should display the calibration value of 9.23. See the Appendix for the table of other
buffer changes with temperature:
5 ° C 1.67
10 ° C 1.67
15 ° C 1.67
20 ° C 1.68
25 ° C 1.68
30 ° C 1.68
35 ° C 1.69
40 ° C 1.69
45 ° C 1.67
50 ° C 1.67
4.01 7.00 10.01
4.01 7.00 9.21
4.00 7.00 9.00
4.008 6.865 9.184
4.65 6.79 9.23
4.003 6.864 9.182
4.00
4.00
4.00
4.00
4.00
4.01
4.02
4.03
4.00
4.00
11.00
12.00
12.454
12.75
12.460
6.95 9.39
6.92 9.33
6.90 9.28
6.88 9.23
6.86 9.18
6.85 9.14
6.84 9.11
6.84 9.07
6.95 9.39
6.92 9.33
EN-13
13.21
13.01
12.82
12.64
12.46
12.29
12.13
11.98
13.21
13.01