5 Measuring
16
The pH value is calculated based on the negative common logarithm of the
hydrogen ion activity (this is often approximately the same as the hydrogen ion
concentration):
The abbreviation "pH" stands for pondus Hydrogenii (Latin: pondus = weight;
Hydrogenium = hydrogen).
Since the pH value is dependent on temperature, it should always be recorded
together with the measured temperature.
Example: pH 5.87 at 22.8 °C.
The pH measurement is a very precise but also sensitive measurement. The
measured signals are very weak (high-impedance), especially when measured
using weak/ion-deficient media.
The following points should therefore be observed:
• Avoid malfunctions (electrostatic charges, etc.)
• Stir measurement solution slowly to achieve a stable measured value
• Dry plug-in contacts and keep them clean
• If possible, do not immerse the combination electrodes in the measurement
solution beyond the shaft for a long time (except for with special waterproof
versions)
• Configure the combination electrode sufficiently frequently (calibration
interval is dependent on the combination electrode and the usage and can
vary between an hour and several weeks)
• Use a suitable combination electrode.
Measuring without temperature probe
✱
Insert the pH combination electrode and the temperature probe into the
solution and gently stir until a stable measured value is achieved.
✱
Adjust the temperature value of the measurement solution using the
and
keys.
c(H
+
) = hydrogen ion concentration
in mol/l
ƒ
(H
+
) = activity coefficient of the
hydrogen ions (usually < 1)
pH value =
c(H ) × (H
+
+
¦
)
1 mol/l
–log
10
(
)
The measured pH value appears on the main display
and the set temperature appears on the subsidiary dis-
play of the device.
rH
mV
mV
H
pH
ATC
ok
AL Logg
pH
CAL
All manuals and user guides at all-guides.com
all-guides.com
Summary of Contents for 202710
Page 2: ...All manuals and user guides at all guides com ...
Page 6: ...Contents All manuals and user guides at all guides com a l l g u i d e s c o m ...
Page 56: ...15 China RoHS 56 All manuals and user guides at all guides com a l l g u i d e s c o m ...
Page 57: ...All manuals and user guides at all guides com ...
