Conductivity meter working principle and precautions - Solutions - Huaqiang Electronic Network

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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, bases and salts contained in it. When their concentration is low, the conductivity increases with the increase of concentration. Therefore, this index is often used to estimate the total amount of ions in water. Concentration or salt content.
Conductance (G) is the reciprocal of the resistance (R). Therefore, when two electrodes (usually a platinum electrode or a platinum black electrode) 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 spacing L (cm) and inversely proportional to the cross-sectional area A (cm2) of the electrode, namely:
R = ρ × (L / A), where ρ is the resistivity, which is a resistance of 1 cm 2 in length and a cross-sectional area of ​​1 cm 2 , the size of which depends on the nature of the substance.
According to the above formula, the conductance (G) of the conductor can be expressed as follows:
G=1/R=(1/ρ)×(A/L)=K×(1/J), where K=1/ρ is called conductivity, and J=L/A is called electrode constant electrolyte solution conductance. The rate refers to the conductance of a solution of 1 cm3 between two parallel electrodes separated by 1 cm. It can be seen from the above formula that when the electrode constant (J) is known and the solution resistance (R) or conductance (G) is measured, the conductivity can be determined.
Conductivity meter structure 1, electrode constant adjustment button: constant adjustment for different electrodes 2, temperature knob: temperature compensation of the measured solution 3, range switch button: calibration / range selection switch, sub-calibration, 20μs, 200μs, 2000μs 4ms in 20ms 4, calibration adjustment knob: calibration range fullness 5, the use of the rear panel structure conductivity meter. Because the conductivity is proportional to the concentration of ions in the solution in most cases, it is easy to determine the solution by measuring the conductivity. The total dissolved solids concentration and the salinity of the solution. Common applications are: boiler blowdown, desalination, reverse osmosis, salinity measurement, water/wastewater treatment.
Precautions for use of conductivity meter 1. The container containing the solution to be tested must be clean and free from ionic contamination.
2. High-purity water should be measured quickly after being placed in the container, otherwise the conductivity will decrease quickly because the dissolved water in the air will become carbonate ions.
3. The lead of the electrode should not be wet, otherwise it will not be measured.