Analysis of working principle of acid-base concentration meter
The acid-base concentration meter indirectly measures the concentration of the solution by measuring the conductivity of the solution. It is known that at a certain constant temperature, the conductivity of the low-concentration electrolyte corresponds to the concentration of the solution. When the temperature changes, the conductivity also changes, ie the concentration of the solution is a function of conductivity and temperature.
It uses a conductance electrode sensor for measurement (the concentration electrode material is platinum), in order to avoid electrode polarization, the instrument generates a high-stability sine wave signal and adds it to the electrode, and the current flowing through the electrode is proportional to the concentration of the measured solution. The current flowing through the electrode is measured by the preamplifier and converted into a voltage signal, and the voltage signal reflecting the concentration value is obtained after program-controlled amplification, phase-sensitive detection and filtering; the microprocessor switches the temperature signal and the concentration signal alternately, After calculation and temperature compensation calculation, it is converted and displayed as the measured concentration value and real-time temperature value at 25°C.
