Abstract: There is described a particle size distribution analysis apparatus comprising an oscillatory assembly, the oscillatory assembly comprising a receptacle for receiving a powder sample and having an opening through which powder may be discharged, the opening being variable in size, and support means allowing the receptacle to reciprocate along an arcuate path, entry means for introducing the sample into the receptacle, adjusting means for varying the size of the opening, bias means to urge the oscillatory assembly towards a datum position, and drive means to induce oscillations of the oscillatory assembly. Detector means may be provided to determine a characteristic of the oscillations of the oscillatory assembly and hence determine the mass of powder remaining in the receptacle.

Abstract: The application describes a particle size analyser comprising a horizontally held close-coiled helical spring which is partly filled with the powder under test. The operation of the technique involves stretching the spring to various known lengths and vibrating it in the lateral direction at or around its first harmonic resonant frequency with a low amplitude of vibration. Measurements of the mass of the powder discharged from spring coils for a given spring extension and relating the latter to the particle size of the discharged powder by reference to a previously generated calibration curve provide data on the particle size distribution.