Development and characterization of a new thief sampling device for cohesive powders

New sampling probes and methods for investigating cohesive powders are conceived, designed and characterized. Probes are made of two metallic shells (a slide and a cover) which need to be inserted sequentially into the bed of powder in order to extract representative samples. The thin profile of the shells, combined with a particular insertion procedure, is intended to minimize stresses on the powder; thereby reducing both the invasiveness and the dragging of material through the bed. Probes of similar design with different shape and size have been tested on stratified beds of cohesive powders of different colors. Sampling performances are quantitatively compared among different probes (for size and shape) and also with literature data. The comparison has indicated that the new sampling devices effectively improved sampling efficiency, reliability and possibilities. The simple construction and use suggest they can be viable and effective alternatives to traditional probes for cohesive mixtures.