Yokogawa 2-Wire Dual Channel Transmitter/Analyzer FLXA21 - Manual (Page 213)

<Appendix 1 For pH/ORP>
App.1-1
IM 12A01A02-01E 5th Edition : Oct. 31, 2013-00
Appendix 1 For pH/ORP
n Buffer tables
The following tables show the details of the buffer solutions selectable in Calibration settings of
pH (Section 4.2.4) (unit: pH).
Table 1 NIST (IEC 60746-2)/DIN 19266
0°C 5°C 10°C 15°C 20°C 25°C 30°C 35°C 38°C 40°C 45°C 50°C 55°C 60°C 70°C 80°C 90°C 95°C
1.68 pH 1.668 1.670 1.672 1.675 1.679 1.683 1.688 1.691 1.694 1.700 1.707 1.715 1.723 1.743 1.766 1.792 1.806
4.01 pH 4.003 3.999 3.998 3.999 4.002 4.008 4.015 4.024 4.030 4.035 4.047 4.060 4.075 4.091 4.126 4.164 4.205 4.227
6.87 pH 6.984 6.951 6.923 6.900 6.881 6.865 6.853 6.844 6.840 6.838 6.834 6.833 6.834 6.836 6.845 6.859 6.877 6.886
9.18 pH 9.464 9.395 9.332 9.276 9.225 9.180 9.139 9.102 9.081 9.068 9.038 9.011 8.985 8.962 8.921 8.885 8.850 8.833
Table 2 DIN 19267 (German buffers) so called: technical buffer solutions
0°C 10°C 20°C 25°C 30°C 40°C 50°C 60°C 70°C 80°C 90°C
4.65 pH DIN 4.670 4.660 4.650 4.650 4.650 4.660 4.680 4.700 4.720 4.750 4.790
6.79 pH DIN 6.890 6.840 6.800 6.790 6.780 6.760 6.760 6.760 6.760 6.780 6.800
9.23 pH DIN 9.480 9.370 9.270 9.230 9.180 9.090 9.000 8.920 8.880 8.850 8.820
Table 3 US technical buffers
0°C 5°C 10°C 15°C 20°C 25°C 30°C 35°C 40°C 45°C 50°C 55°C 60°C
4.0 pH US 4.000 3.998 3.997 3.998 4.001 4.005 4.001 4.018 4.027 4.038 4.050 4.064 4.080
7.0 pH US 7.120 7.090 7.060 7.040 7.020 7.000 6.990 6.980 6.988 6.978 6.970 6.890 6.980
10.0 pH US 10.317 10.245 10.179 10.118 10.062 10.012 9.966 9.926 9.889 9.856 9.828 9.828 9.828
Table 4 FREE PROGRAMMABLE (Default settings based on rounded NIST values).
0°C 5°C 10°C 15°C 20°C 25°C 30°C 35°C 40°C 45°C 50°C 55°C 60°C 65°C 70°C 75°C 80°C
buffer 4 4.00 4.00 4.00 4.00 4.00 4.01 4.02 4.02 4.04 4.05 4.06 4.08 4.09 4.11 4.13 4.15 4.16
buffer 7 6.98 6.95 6.92 6.90 6.88 6.87 6.85 6.84 6.84 6.83 6.83 6.83 6.84 6.84 6.85 6.85 6.86
buffer 9 9.46 9.40 9.33 9.28 9.23 9.18 9.14 9.10 9.07 9.04 9.01 8.99 8.96 8.94 8.92 8.90 8.89
The freely programmable table is populated with a basic set of data to provide a start for the
user configuration. This table is intended for the user to be able to choose his buffer solutions to
suit his own preference. The data concerning the pH temperature characteristic will need to be
obtained from the supplier of the buffers.
NOTE
Yokogawa recommend the use of NIST (primary buffer standards) rather than buffers which have
been adjusted by the addition of acid or alkaline materials to the buffer composition. In this way
the customer gets a recognized standard, as well as the best buffer capacity (the ability to resist
pH change with contamination).
App.
PH
SENCOM