Z03.0.0X.6C-11
Operating manual GE xxx serie
page 6 of 12
3
Basics
3.1 pH measurement
The pH value describes the acidic or alkaline behaviour of an aqueous solution.
pH values below 7 are acidic (smaller values indicate higher acidity), and values above 7 are
alkaline; pH 7 = neutral.
The pH measurement is very precise, but also sensitive. The measured signals are very weak
(high-ohmic), especially when measured in weak or low-ion media. Therefore, always take
measures to
To determine the pH value of a solution, it should always be recorded together
with the measuring temperature, the reason is that most liquids change their pH
value with the temperature.
- avoid interference (electrostatic charges, etc.)
- keep plug contacts clean and dry
- prevent electrodes (except special waterproof versions) from extended immersion above the
shaft
- calibrate the electrode at sufficient intervals (see below). The frequency of calibration can
range from every hour to several weeks, depending on the electrode and the application.
- use a suitable electrode.
3.2 Design of electrode
In most cases so-called combination electrodes are used. That means that all needed elements are
integrated in a single electrode (including reference electrode).
Sometimes even a temperature sensor is integrated. (The picture shows an electrode without
temperature sensor)
1. Coaxial cable
2. Reference electrode
3. Measuring electrode
4. Refill opening
5. Electrolyte
6. Internal buffer
7. Diaphragm
8. Glass membrane / source layer
