The measurement of the specific conductivity in aqueous solutions is becoming increasingly important for the determination of impurities in water or the concentration measurement of dissolved chemicals.
What is conductivity?
Conductivity is the measure of a solution's ability to transmit or conduct an electric current. The term conductivity is derived from Ohm's law, E=I-R; where voltage (E) is the product of current (I) and resistance (R); resistance is determined by voltage/current. When a voltage is connected to a conductor, a current will flow, which depends on the resistance of the conductor. Conductivity is simply defined as the reciprocal of the resistance of a solution between two electrodes.
Another way is to use 4-electrode conductivity sensors made of corrosion-resistant materials. The advantage of a 4-electrode conductivity sensor over an inductive sensor is the scale compensation and the ability to measure low (less than 100µS/cm) conductivity (a feature that is especially important when measuring almost 100% hydrofluoric acid).
Ebora supplies conductive conductivity sensors as well as inductive conductivity sensors.
The inductive plastic conductivity sensor C6.30 with 4...20 mA is widely used in air scrubbers and has an internal temperature compensation.
The Hengesbach conductive conductivity sensor is used against many in hygienic applications and is often used to check whether the CIP cycle has been completed.