the reading is stable(the symbol will be shown on the screen), then press
and display shows 9.18, next press to confirm the third point calibration and quit
calibration mode and enter measuring mode, “ ” will be shown on the right
bottom and means the instrument is calibrated at three points.
2.5. Calibration instructions
2.5.1. This instrument has one point, two point or three point calibration, after the first
point calibration is finished, press to quit calibration mode and enter measuring
mode, “ ” will be shown on the left bottom. When measurement accuracy is no
more than ±0.1pH, choose one buffer solution to calibrate one point is enough
according to the measurement range.
2.5.2. When the second point calibration is finished, press to quit calibration
mode and enter measuring mode, the symbol of two point calibration “ ” will
be shown on the bottom left screen. If you only measure acidic solutions, then choose
pH 4.0 & 6.86 buffers for calibration. If you only measure alkaline solutions, then
choose pH6.86 & 9.18 buffers for calibration.
2.5.3. If the measurement range is wide or the pH electrode is ageing after a long time,
three point calibration is required, which will lead to higher accuracy. For the first time
use of a new pH electrode, it must be calibrated at three points and adjust the slope
of the instrument same as the pH electrode.
3. pH Solution Measurement
Wash the pH electrode & temperature electrode and wave them dry, put them into
the solution, shake the electrode and let it be static, then wait until the reading is
stable and the symbol appear on the screen, then the reading is its pH value.
NOTE: Based on principle of isothermal measurement, the closer of the temperature
of tested solution with that of buffer solution, the more accurate of the measurement,
please obey this rule when doing the test.
