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- 7 -
Calibration
USA Series
NIST Series
Indication icon
Recommended
1-pt
7.00 pH
6.86 pH
Accuracy ≥ 0.1 pH
2-pt
Option A
1st pt: 7.00 pH
2nd pt: 4.00 or 1.68 pH
Option A
1st pt: 6.86 pH
2nd pt: 4.01 or 1.68 pH
Range < 7.00 pH
Option B
1st pt: 7.00 pH
2nd pt: 10.01 or 12.45 pH
Option B
1st pt: 6.86 pH
2nd pt: 9.18 or 12.45 pH
Range >7.00 pH
3-pt
1st pt: 7.00 pH
2nd pt: 4.00 or 1.68 pH
3rd pt: 10.01 or 12.45 pH
1st pt: 6.86 pH
2nd pt: 4.01 or 1.68 pH
3rd pt: 9.18 pH or 12.45 pH
Range: 0 to 14.00 pH
6.8 For the self-diagnosis information, please refer to the table below:
Symbol
Self-Diagnosis information
Potential problems and how to fix
The pH calibration solution cannot be
recognized by the meter.
1. Make sure the probe is fully immersed in the calibration
solution.
2. Check if calibration solution is expired or polluted.
3. 1st point of pH calibration must be pH 7.00 or 6.86. See 6.6.
4. Please check whether pH probe is damaged or broken. If so,
please replace with a new one.
5. The glass bulb or junction is severely contaminated. Please
use a soft brush with soap water to clean it thoroughly. Then
soak it in 3M KCL 3-5 hours before performing calibration
again.
is pressed before measurement
is fully stabilized.
Wait for to stay on screen before pressing
During calibration, readings being unstable for
over 3 minutes.
1. Please check whether pH probe is damaged or broken. If so,
please replace with a new one.
2. The glass bulb or junction is severely contaminated. Please
use a soft brush with soap water to clean it thoroughly. Then
soak it in 3M KCL overnight before performing calibration
again.
3. The probe is aged (used for over a year and has a much
slower response). A replacement is needed.
pH probe zero electric potential out of range
(<-60mV or >60mV)
1. Check whether pH buffer solutions comply with the USA or
NIST standard.
2. Check whether pH buffers are expired or contaminated.
3. Please check whether pH probe is damaged or broken. If so,
please replace with a new one.
4. The probe is aged (used for over a year and has a much
slower response). A replacement is needed.
5. The probe is invalidated (Er4/Er5 repetitively appears, and
problems 1, 2, 3 are excluded). Probe replacement is needed.
pH probe slope out of range
(<85% or >110%)
The calibration reminder is triggered. It’s time
to perform a new pH calibration.
Perform pH calibration or cancel calibration reminder in ZenTest App settings.
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