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6.2.3. Rinse off the pH electrode in pure water and remove excess water, then insert it into the pH4.00
buffer solution, make a quick stir and then hold it still. When the reading is stabilized and stays on
screen, short press again to finish the 2
nd
point calibration. “
4.00 pH
” will start flickering and a
flickering
c3
will show up, indicating the 2
nd
point calibration has been finished and the meter is entering
the 3
rd
point calibration.
6.2.4. Rinse off the pH electrode in pure water and remove excess water,
then insert it into the pH10.01 buffer solution, make a quick stir and then
hold it still. When the reading is stabilized and stays on screen, short
press again to finish the 3
rd
point calibration. “
10.01 pH
” will start
flickering and then the meter will return to measurement mode.
will show up at the bottom left (see picture 4-1), indicating all three points of calibration
are finished.
6.3
Notes about pH Calibration
1)
Keeping the freshness and cleanliness of calibration buffers is essential for accurate pH
measurement. The small bottles of pH buffers come with the meter should be replaced within 3
months after opening. The new buffer solutions should be made by a legitimate lab supply
manufacturer. Avoid sunlight and air contact when the buffers are not being used, and store at room
temperature.
2)
This meter can adopt random 1-point, 2-point or 3-point automatic calibration. During calibration,
short press to return to measurement mode. When the measurement accuracy is ≤±0.1pH,
choose a buffer that’s close to the estimated measurement range and perform 1-point calibration
would be good. Choose pH4.00 and pH7.00 to calibrate if the measurement range is within the acidity
range (<pH 7) and choose pH7.00 and pH10.01 to calibrate if just within the alkalinity range (>pH 7).
3)
Choose 3-point calibration to achieve a more accurate measurement if the measurement range is
wide, or if the electrode has not been used for long. When connecting a new pH electrode, it must
be calibrated at 3 points.
4)
The frequency that you need to calibrate your meter depends on the tested samples, condition of
electrodes, and the requirement of the accuracy. For High-Accuracy measurements (≤ ±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. In the following cases, the meter
