Xylem Multi 3420 - Manual (Page 44)

Operation Multi 3420
44 ba75864e11 02/2011
4.7.4 pH calibration
Why calibrate? During the operation of an IDS pH sensor, the zero point (asymmetry)
and
slope of the sensor change with time.As a result, an inexact measured
value is displayed. Calibration determines the current values of the
zero point and slope of the pH sensor and stores them in the measuring
instrument.
Thus, you should calibrate at regular intervals.
When do you have to
calibrate?
z When the calibration interval has expired
Buffer sets for
calibration
You can use the buffer sets quoted in the table for an automatic calibra-
tion. The pH values are valid for the specified temperature values. The
temperature dependence of the pH values is taken into consideration
during the calibration.
No. Buffer set * pH values at
1 ConCal Any Any
2 NIST/DIN
DIN buffers according to DIN 19266
and NIST Traceable Buffers 1.679
4.006
6.865
9.180
12.454
25 °C
3 TEC
WTW Technical buffers 2.000
4.010
7.000
10.011
25 °C
4 Merck 1* 4.000
7.000
9.000 20°C
5 Merck 2 * 1.000
6.000
8.000
13.000
20°C
6 Merck 3 * 4.660
6.880
9.220 20°C
7 Merck 4 * 2.000
4.000
7.000
10.000
20°C