The basic principle and characteristics of the conductivity meter

Conductivity is a digital representation of the ability of a solution to conduct current. The conductivity of water has a certain relationship with the amount of inorganic acids, alkalis and salts it contains. When their concentrations are low, the conductivity increases with the increase of concentration. Therefore, this indicator is often used to estimate the total amount of ions in water. Concentration or salt content.

The conductance (G) is the reciprocal of the resistance (R). Therefore, when two electrodes (usually platinum electrodes or platinum black electrodes) are inserted into the solution, the resistance R between the two electrodes can be measured. According to Ohm's law, when the temperature is constant, this resistance value is proportional to the electrode distance L (cm) and is inversely proportional to the cross-sectional area A (cm2) of the electrode, that is, R=ρ×(L/A); where ρ is the resistivity and is long 1cm, the resistance of the conductor with a cross-sectional area of ​​1cm2 depends on the nature of the material.

According to the above formula, the conductance of the conductor (G) can be expressed as follows: G = 1/R = (1/ρ) × (A/L) = K × (1/J); where K = 1/ρ For the conductivity, J=L/A is referred to as the electrode constant; the conductivity of the electrolyte solution refers to the conductance of a 1 cm3 solution between two parallel electrodes separated by 1 cm. From the above equation, when the electrode constant (J) is known and the solution resistance (R) or conductance (G) is measured, the conductivity can be determined.

Conductivity Meter Features

Conductivity meter is an essential instrument for measuring the conductivity of aqueous solutions in the laboratory. It is widely used in petroleum, chemical, biological, pharmaceutical, sewage treatment, environmental monitoring, mining and metallurgy as well as universities and research institutes. The features of the instrument are as follows:

1, the instrument has a constant electrode and temperature compensation.

2. The instrument adopts a stable performance sine wave generator composed of high-performance integrated circuits, so the reading is stable and the drift is small.

3. The instrument uses a phase-sensitive detector to suppress the influence of the distributed capacitance of the electrode lead on the measurement. Therefore, the instrument does not require capacitance compensation, and the measurement accuracy of low conductivity is greatly improved.