Coulter Counter

A Coulter counter measures particle size and concentration using the electrical sensing zone principle: as particles pass through a small orifice separating two electrodes, each displaces electrolyte and changes impedance proportional to its volume. The result is a precise number-based particle-size distribution. This technique complements laser diffraction by resolving fines that strongly affect clarity and filter loading. Reliable results depend on correct dilution, degassing, and calibration with traceable standards. Because it yields number-weighted data, conversion to volume-weighted or surface-weighted measures may be needed for hydraulic calculations. Linking Coulter counts to ∆p and turbidity trends allows early detection of media breakthrough or feed variation.