Apera Instruments SX811-BS, Instruction Manual

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Table-2
Calibration icon
pH standard buffer series
USA CH NIST
3-Point
calibration
1.68 and 4.00 pH 1.68 and 4.00 pH 1.68 and 4.01 pH
7.00 pH 6.86 pH 6.86 pH
10.01 pH 9.18 pH 9.18 pH
4.1.2 3-Point Calibration
The meter can adopt 1 to 3 points’ calibration. The 1
st
point must be using 7.00 pH (or 6.86 pH) buffer
solution, and then choose other buffers to do 2
nd
point and 3
rd
point. Please refer to Table-3 for details. In
the process of calibration, the slope of acidity range and alkalinity range will be displayed.
Table-3 Calibration Mode
CH USA NIS
Calibration
icon
When to adopt
1-Point
Calibration
6.86 pH 7.00 pH 6.86 pH
accuracy≤ ±0.1
pH
2-Point
Calibration
6.86 pH and
4.00/1.68 pH
7.00 pH and
4.00/1.68 pH
6.86 pH and
4.01/1.68 pH
0 to 7.00 pH
6.86 pH and 9.18
pH
7.00 pH and 10.01 pH 6.86 pH and 9.18 pH
7.00 to 14.00
pH
3-Point
Calibration
6.86pH, 4.00/
1.68 pH, and
9.18 pH
7.00pH, 4.00/
1.68 pH and 10.01 pH
6.86pH, 4.01/
1.68pH, 9.18 pH
0 to 14.00 pH
4.1.3 How often to calibrate
The frequency that you need to calibrate your meter depends on the tested samples, performace of
electrodes, and the requirement of the accuracy. For High-Accuracy meaustements (≤ ±0.02pH), the
meter should be calibrated before test every time; For ordinary-accuracy Measurements (≥±0.1pH), once
calibrated, the meter can be used for about a week or longer.
4.1.4 Calibration reminder
Preset the interval between calibrations (starting from the time when you set
it), and then the meter will remind you to calibrate at the end of that interval.
For detailes, please see P1.2 (6.3). When the preset time is reached, Er6 icon
will be displayed at the lower right corner of the LCD (as showed in graph-8).
At the time, the meter can still be operated. It is just reminding you to do
calibration in order to ensure its accuracy. After calibration, the Er6 icon will disappear;
To make it disappear, users can also choose NO in P1.2 in parameter setting.
Graph-8