Conductivity meter electrodes are generally divided into two types: two electrode type and multi electrode type.

The electrode of the two electrode conductivity meter is currently the most commonly used type of conductivity electrode in China. The structure of the experimental two electrode conductivity meter electrode is to sinter two platinum plates on two parallel glass plates or on the inner wall of a circular glass tube, adjust the area and distance of the platinum plates, and make conductivity electrodes with different constant values. Usually there are types such as K=1, K=5, K=10, etc. The electrode of the two electrode conductivity meter used on online conductivity meters is often made into a cylindrical symmetrical electrode. When K=1, graphite is often used, and when K=0.1 or 0.01, the material can be stainless steel or titanium alloy. The electrode of a multi electrode conductivity meter generally has several circular electrodes on the support, and different combinations of series and parallel of the circular electrodes can be used to make conductivity meter electrodes with different constants. The material of the annular electrode can be graphite, stainless steel, titanium alloy, and platinum.

There are four electrode types and electromagnetic types for conductivity meter electrodes. The advantage of four electrode conductivity meters is that they can avoid measurement errors caused by electrode polarization, and are commonly used in experimental and online conductivity meters abroad. The characteristic of the electrode of an electromagnetic conductivity meter is that it is suitable for measuring solutions with high conductivity. It is generally used in industrial conductivity meters or used to make single component concentration meters based on its measurement principle, such as hydrochloric acid concentration meters, nitric acid concentration meters, etc.

Due to differences in the concentration and temperature of the measuring solution, as well as variations in the accuracy and frequency of the measuring instrument, there may be significant errors in the electrode constant K of the conductivity meter. After use for a period of time, the electrode constant may also change. Therefore, for newly purchased conductivity meter electrodes and conductivity meter electrodes that have been used for a period of time, the electrode constant should be remeasured and calibrated. When measuring the electrode constant of the conductivity meter, the following points should be noted:

When measuring, a matching conductivity meter should be used, and other models of conductivity meters should not be used.
2. The temperature of the KCL solution for measuring electrode constants should be close to the actual temperature of the measured solution.
3. The concentration of KCL solution for measuring electrode constants should be close to the actual concentration of the measured solution.

The principle of measuring conductivity is actually to determine the resistance of the solution between parallel electrodes according to Ohm's law. However, when current passes through the electrode, oxidation or reduction reactions occur, which change the composition of the solution near the electrode and cause a "polarization" phenomenon, resulting in serious errors in conductivity measurement. Therefore, using high-frequency alternating current measurement method can alleviate or eliminate the polarization phenomenon mentioned above, because the oxidation and reduction on the electrode surface quickly alternate, and the result can be considered that no oxidation or reduction occurs.

The conductivity meter consists of conductive electrodes and electronic units. The electronic unit uses an appropriate frequency of AC signal to amplify and convert the signal into conductivity. The instrument is also equipped with a temperature measurement system that matches the sensor, a temperature compensation system that can compensate for the standard temperature conductivity, a temperature coefficient adjustment system, a conductivity cell constant adjustment system, and an automatic shifting function.