Abstract: The size ranges of particles separated on a stack of sieves of different mesh sizes is measured automatically. The stack is clamped together and shaken as a unit to separate the respective fractions, following which the sieves are sequentially separated from the stack and inverted one at a time to dump the fraction retained on each, onto a scale. Each fraction is weighed separately and their relative proportions can be calculated automatically. In a preferred embodiment the sieves are individually cantilevered from a vertical conveyor. The sieves are inverted one by one to dump their contents by advancing them around a horizontal roll at a lower end of the conveyor.

Abstract: An apparatus for automatically removing particulate matter from a weighing pan of a particle-size analyzer. The apparatus includes a weighing pan having a hinged door to provide a discharge outlet for the particular matter and a wiper blade assembly for clearing the particulate matter from the weighing pan. The apparatus further includes a driving mechanism, preferably a rodless cylinder, for operating the wiper assembly in the weighing pan.

Abstract: An apparatus for automatic screen analysis of a granular material in which the material is screened from a polygonal drum which is divided crosswise into at least two chambers by a transverse partition. A first chamber has progressively coarser screens on each of its faces except one, which has a downward slanting ramp for transferring the sample into a second chamber. Particles are transferred or chuted into the second chamber after they have been screened on all the screens of the first chamber. The second chamber has screens progressively coarser than those in the first chamber, for making more cuts. This construction increases the number of graded screening surfaces available without requiring greater drum length or more sides.

Abstract: Disclosed is a device for sequentially cleaning the screens of a particle size analyzer of the indexing drum type, as each screen moves out of the screening position. The cleaning member is preferably removed from the drum during each screening step. The particles dislodged from the screen being cleaned are returned to the sample being analyzed in a manner which maintains the accuracy of the analysis. In an alternative embodiment, each screen is cleaned during a screening step, at an indexed position other than the screening position.