5 ph calibration, Ph calibration – Xylem ProLab 2000 User Manual
Page 43
ProLab 2000
Operation
43
ba75577e05
11/2013
4.5.5
pH calibration
Why calibrate?
pH electrodes age. This changes the zero point (asymmetry) and slope
of the pH electrode. As a result, an inexact measured value is
displayed. Calibration determines the current values of the zero point
and slope of the electrode and stores them.
Thus, you should calibrate at regular intervals.
When do you have to
calibrate?
After connecting a non-ID electrode
If the CalClock has expired and flashes
Buffer sets for
calibration
You can use the buffer sets quoted in the table for an automatic
calibration. The pH values are valid for the specified temperature
values. The temperature dependence of the pH values is taken into
account during the calibration.
No.
Buffer set *
pH values
at
1
DIN buffers according to DIN
19266 and NIST Traceable
Buffers
1.679
4.006
6.865
9.180
12.454
25 °C
2
Technical buffers
2.000
4.010
7.000
10.011
25 °C
3
Merck1*
4.000
7.000
9.000
20°C
4
Merck2 *
1.000
6.000
8.000
13.000
20°C
5
Merck3 *
4.660
6.880
9.220
20°C
6
Merck4 *
2,000
4,000
7,000
10,000
20 °C
7
Merck5 *
4,010
7,000
10,000
25 °C