The ECA 2100 laboratory charge analyser accurately measures colloidal and ionic charge of the wet end using the streaming current principle, which is comparable to zeta potential.. Charge demand is determined with polyelectrolyte titration to the isoelectric point, either manually or by use of an automatic titrator.

Streaming Current Principle
The measurement cell of the ECA Laboratory charge analyser consists of a reciprocating teflon piston in a probe assembly. Particles and dissolved materials are attracted to the surfaces of the probe by Van Der Waals forces. Counter ions surround these particles. The motion of the piston generates shear forces, which causes the counter ions to migrate. Electrodes in the probe measure the flow of counter ions, inherently defined as an electrical current. The current is electronically processed and displayed on the touchscreen as the STREAMING CURRENT VALUE (SCV). For most samples in a paper mill, the SCV will be negative, indicating a net anionically charged sample.

Charge Demand (Isoelectric Titration)
The ECA 2100 lab charge analyser allows the operator to determine the charge demand of a sample. Charge demand is quantified by adding a polymer of opposite charge to the sample until the SCV equals zero, which is defined as the isoelectric point. Addition of the polymer (or process additive) can be achieved by hand or automatic titration. The SCV can be displayed as a function of time on the touchscreen. Whether in the form of a graph or data table, this increases the operator's understanding of the titration in real time.