Conductivity meter principle and precautions

Conductivity Meter Principles Conductivity is the ability to digitally represent the conductivity of a solution. 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), which is inversely proportional to the cross-sectional area A (cm2) of the electrode, that is:

R = ρ × (L / A), where ρ is the resistivity, is a length of 1cm, the cross-sectional area of ​​the resistance of 1cm2 conductor, the size of which depends on the nature of the material.

According to the above formula, the conductance (G) of the conductor can be expressed as:

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 conductivity Rate refers to the conductance of a 1 cm3 solution between two parallel electrodes spaced 1 cm apart. 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 structure 1, electrode constant adjustment button: constant adjustment of different electrodes 2, temperature knob: temperature compensation for the measured solution 3, range switch button: calibration / range selection switch, sub-calibration, 20μs, 200μs, 2000μs , 20ms four files 4, calibration adjustment knob: calibration range fullness 5, the use of the rear panel structure conductivity meter because the conductivity in most cases is proportional to the concentration of ions in the solution, so it is easy to determine the solution within 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.

The use of conductivity meter Notes 1. The container holding the test solution must be clean and free from ion contamination.

2. High-purity water should be measured quickly after it is put into a container, otherwise the conductivity will decrease rapidly because the dissolved water in the air becomes carbonate ion.

3. The lead of the electrode must not be wet, otherwise it will not be accurate.