EFFECT OF FILL LEVEL IN MIXER VISCOMETRY

ABSTRACT The effects of viscometer fluid level on the consistency coefficient (K) and flow behavior index (n) were evaluated using the torque curve method. Experiments with four levels of fill (multiples of the impeller height) with a Haake pitched paddle mixer impeller were conducted. Newtonian fluids and non‐Newtonian fluids were used to determine the k′, k″, K and n values of each sample at different fill levels while keeping the impeller Reynolds number in the laminar flow range. This is the first quantitative study showing that mixer constant value (k′) and rheological properties (especially the K value) obtained from mixer viscometry are a function of fluid fill level. The recommended fluid fill level based on the matching viscosity method is 1.5 times the height of mixer impeller. PRACTICAL APPLICATIONSThe study is useful in mixer viscometry applications aimed at establishing engineering design data and for quality control testing of materials having large particulates, settling problems and phase separation.