ABSTRACT
Consistency-measuring instruments detect consistency of the process fluid as shear forces acting on the sensing element. Consistency is the resistance to deformation or shear by fibrous materials. Consistency is expressed as a percentage, dividing the dry weight of the solids with the unit weight of the wet sample. Velocity influences the consistency reading, and therefore it is advisable to measure consistency in turbulent locations at constant flow rate. There are two basic types of consistency detectors: the fixed and the rotary. The shear force acting in the cylinder, due to the consistency of the process fluid, causes an imbalance of the resistance bridge. Changes in consistency are transmitted through the blade to the force bar causing small changes in the relationship between flapper and nozzle. Optical consistency meters can use a sample cell through which polarized light is passed. The flow bridge, the hydraulic analog of the Wheatstone bridge, can also be used to measure consistency.
