G 1501
Measurement Basics | 5
B-H86.0.12.DB2-2.1
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5
Measurement Basics
5.1
pH measurement
5.1.1
Explanation
The pH value describes the acidic or alkaline behaviour of an aqueous solution. A pH
value below 7 is acidic, a value above 7 is alkaline. A pH value of 7 is neutral.
The pH measurement is very precise, but also sensitive. The measured signals are
very weak and high-ohmic. This is the case, in particularly in low-ion media.
NOTE
In order to detect the pH value of a solution, it should always be recorded together
with the measurement temperature, because most liquids change their pH value with
the temperature.
The following must be observed:
–
avoid interference, electrostatic charges, etc.
–
keep plug contacts clean and dry
–
prevent electrodes which do not have any special waterproof versions from ex-
tended immersion above the shaft
–
calibrate electrodes sufficiently often. The can range from every hour to several
weeks, depending on the electrode and the application
–
Use a suitable electrode
