| In paper coating process, the quality control of coating fluids is an important issue that influences end-product properties. Coating fluid composition is very complex. Quality control depends on several physical properties such as density, pH, solids concentration, viscosity, etc. In an industrial context, the control of these physical properties is important.;One option to control in-line the quality of coating colors consists of measuring its rheological properties and its evolution. The aim of this work is to develop and test a method that allows the determination and monitoring of the viscosity of coating colors in the coating transport line.;Our in-line viscometer is based on an extension of the Metzner-Otto concept widely used in mechanical agitation which enables to relate the effective shear rate to the pressure drop. More specifically, our method lays on the determination of constants Kp and Ks.;From a practical standpoint, two static mixers are inserted in the coating transport pipe and the pressure drop across each mixer is measured. From this, in-line viscosity can be calculated.;Our testing methodology is composed of two steps: (1) system calibration and sensitivity analysis, (2) pressure drop measurement and viscosity calculation (shear thinning fluids and coating model fluids).;Newtonian fluids of different viscosities have been used for calibration purpose and to establish the sensitivity of the apparatus. Results are satisfying: 17% of uncertainty on the results for the viscosity calculated. Moreover coating model fluids reveled phenomena linked to solids content. These phenomena originate some disturbances on the pressure drop measurement. |
