- 15 -
Chart -3 Three-point calibration mode
USA standard
NIST standard
CH standard
Applicable range
One-point
calibration
pH 7.00
pH 6.86
pH 6.86
Accuracy
≤± 0.1pH
Two-point
calibration
pH 7.00 and
pH 4.00/1.68
pH 6.86 and
pH 4.01/1.68
pH 6.86 and
pH 4.00/1.68
< pH 7.00
pH 7.00
and pH 10.01/12.45
pH 6.86 and
pH 9.18/12.46
pH 6.86 and
pH 9.18/12.46
> pH 7.00
Three-point
calibration
pH 7.00,
pH 4.00/1.68 and
pH 10.01/12.45
pH 6.86,
pH 4.01/1.68 and
pH 9.18/12.46
pH 6.86,
pH 4.00/1.68 and
pH 9.18/12.46
pH 0 – 14.00
5.2.3 Calibration information display
1. Automatically display electrode slope in measurement
interface
⚫
Display average slope after two or three point calibration
⚫
Dose not display slope after one point calibration
2. Display last calibration data in pH submenu clause 1.3
5.2.4 Calibration frequency
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 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. In the following cases, the meter must be
re-calibrated:
a)
The electrode hasn’t been used for a long time or a new electrode is connected.
b)
After measuring strong acid (pH<2) or strong base (pH>12) solutions.
c)
After measuring fluoride-containing solution and strong organic solution
d)
There is a significant difference between the temperature of the test sample and the temperature of
the buffer solution that is used in the last calibration.
2020-01-18
16:26:42
