YOKOGAWA PH72, Руководство пользователя

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IM 12B03D02-01E
4-2
4 . Calibration
Canceling Calibration
To cancel the calibration procedure, press
CAL
or
MEAS
key. The meter will
return to measurement mode.
1-point and 2-point Calibrations
There are two types of calibrations: 1-point calibration using only one standard
solution and 2-point calibration using two standard solutions. One-point calibration
is a simplified calibration method which can be used only when the anticipated pH
values of sample solutions are near the certified pH value of a standard solution used
for calibration. Two-point calibration is generally recommended.
Calibration results are not affected by turning off the power and saved until the next
calibration or the initialization of calibration parameters (see Section 5.3 (11)). The
last two calibration results are saved in the meter. Therefore, for 1-point calibration,
first initialize calibration parameters and then perform a 1-point calibration, or without
initializing, perform a 1-point calibration twice using the same standard solution.
4.1 Automatic Calibration
In automatic calibration the Model PH72 Personal pH/ORP Meter automatically
recognizes standard solutions being used and calibrates itself using values of Table
4.1. Two types of standard solutions are preprogrammed: NIST (solutions prepared
in accordance with Japanese standards, factory default) and US (solutions prepared
in accordance with the U.S. standards). If NIST is selected, the meter recognizes
standard solutions with pH 2, 4, 7, 9, and 12. The meter recognizes standard
solutions with pH 4, 7, and 10 if US is selected.
Table 4.1 pH-Temperature Relationship in pH Standard Solutions
• NIST
Temperature °C
Std. Solution
0 5 10 15 20 25 30 35 40 45 50 55 60 70 80
pH2
- 1.668 1.670 1.672 1.675 1.679 1.683 1.688 1.694 1.700 1.707 1.715 1.723 1.743 1.766
pH4 4.003 3.999 3.998 3.999 4.002 4.008 4.015 4.024 4.035 4.047 4.060 4.075 4.091 4.126 4.164
pH7
6.984 6.951 6.923 6.900 6.881 6.865 6.856 6.844 6.838 6.834 6.833 6.834 6.836 6.845 6.859
pH9 9.464 9.395 9.332 9.276 9.225 9.180 9.139 9.102 9.068 9.038 9.011 8.985 8.962 8.921 8.885
pH12
13.423 13.207 13.003 12.810 12.627 12.454 12.289 12.133 11.984 11.841 11.705 11.574 11.449 - -
• US
Temperature °C
Std. Solution
0 5 10 15 20 25 30 35 40 45 50 55 60
pH4 4.000 3.998 3.997 3.998 4.001 4.005 4.010 4.018 4.027 4.038 4.050 4.064 4.080
pH7
7.120 7.090 7.060 7.040 7.020 7.000 6.990 6.980 6.980 6.978 6.970 6.980 6.980
pH10 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