Conductivity measurement 4 cell

Abstract

Conductivity measurement is one of the most important and widely used to measure the quality of water in all spread of industries, labs & institutions. The Conductivity or specifically electrolytic conductivity is defined as the ability of a substance to conduct electric current. AC current is passed through two plate and voltage are measured across the plates, the resistance is offered by the liquid is measured in terms of voltage using ohms law principle. The conductivity measurement’s heart is the cell, among them 2 cell is most commonly used but it has few problem such as polarization, field effects, less measurement range etc, answer to solve this problem is 4 cell, this cell has 4 cells it can be of different forms – rings, pins, rectangular and square shaped etc. The 4 cell concept helps to totally remove the field effect, polarization problems, cell constant is the key factor, there are different types of cell constant K=0.01, K=0.1, K= 1.0 and K= 10.0. The cell constant is chosen based on the ranges, cell constant 0.01 is used of low conductance measurement such as ultra pure water. As the conductivity goes higher cell constant will also chosen higher. Frequency - lower the conductivity measurement lower is the frequency (32 Hz) as the measurement value goes up the frequency should also go up to get optimum results. The electronics has oscillator which generate required frequency, then high impedance op-amp and frequency dividers are used to measure conductivity. Application of conductivity measurement such as concentration, salinity, resistivity, Total dissolved solids (TDS). All most all industries need this instrument even the drinking water, swimming pool also need this measurement.