Abstract: Apparatus for determining flowability of a powder by sensing powder avalanching includes a sample drum having a generally cylindrical sample chamber for holding a powder sample, a support frame including a drum shaft for supporting the sample drum for rotation, a drive motor and a drive mechanism coupled between the drive motor and the drum shaft such that the drum rotates when the drive motor is energized. The apparatus further includes an avalanche sensor for sensing avalanching of the powder sample within the sample chamber as the sample drum rotates. The avalanche sensor may be implemented as a backlash sensor for sensing intermittent reverse angular displacement of the sample drum caused by avalanching of the powder sample. A torque loading sensor may also be used to sense avalanching of the powder sample. A controlled gas may be circulated through the sample chamber by a gas conditioning system. The gas in the sample chamber can be measured and/or controlled.

Abstract: A powder dispersion system, including a powder disperser and a control unit, supplies a controlled particle stream to a particle sizing system, instrument, or other processing device. The powder disperser includes a dynamic shear dispersion assembly and may include a fluidization assembly. An impact surface for deagglomeration of particles is located within a rapid acceleration chamber of the dynamic shear dispersion assembly. The particles are accelerated from the impact surface through an annular nozzle. A feedback loop dynamically controls the dynamic shear force applied to the aerosol transport gas, which in turn places reaction forces upon the particles, within the annular nozzle. The fluidization assembly includes a primary chamber for holding a powder sample and a secondary chamber for entraining particles of the powder sample in a transport gas stream. A pulsed gas jet directed into the primary chamber disperses particles of the powder sample into the secondary chamber.

Abstract: Apparatus for volumetric sampling of a particle-laden gas includes a housing defining a sample chamber, a piston movable in the sample chamber so as to vary the volume of the sample chamber and a drive assembly for moving the piston in the sample chamber. The housing includes an inlet for admitting a particle laden gas into the sample chamber and an outlet for carrying the particle-laden gas from the sample chamber. The piston draws a predetermined volume of the particle-laden gas into the sample chamber through the inlet at a first flow rate during an intake phase, and exhausts the predetermined volume of the particle laden gas from the sample chamber through the outlet for analysis at a second flow rate during an exhaust phase. The outlet of the sample chamber is typically connected to a particle sizing instrument for measuring particles in the particle laden gas. The sample volume and the flow rate during the intake phase can be selected to match the parameters of the device or process being analyzed.

Abstract: A system for monitoring and analyzing impurities in a liquid by analyzing the non-volatile residue of droplets of the liquid includes a droplet generator for generating a stream of droplets of the liquid, a droplet inspection unit, a drop-on-demand unit for removing selected droplets from the stream of droplets, a heat exchanger for drying the droplets to provide non-volatile residue particles, and a particle size measurement unit. The droplet inspection unit determines the diameters of the droplets. A feedback arrangement from the droplet inspection unit controls droplet diameter by varying the droplet generation rate. The drop-on-demand unit removes a selected fraction of droplets from the droplet stream so as to reduce vapor loading in the heat exchanger and prevent agglomeration of droplets. The heat exchanger includes a first section for gradually increasing the temperature of the stream of droplets and a second section for maintaining the stream of droplets at the boiling temperature of the liquid.

Abstract: Apparatus, intended primarily for use in an aerodynamic particle sizing system, for generating a pair of closely-spaced, substantially parallel light beams and for determining particle sizes by measuring the times of flight of particles between the two light beams. The apparatus for generating the light beams includes a laser source, an aperture slit for establishing the shape of the beams, a cylindrical lens for focusing the laser beam on the aperture slit, a diffraction grating for converting the beam from the aperture slit into diffracted beams in the zero order lobe and one first order lobe and a transfer lens for directing the diffracted beams as substantially parallel beams.

Abstract: Apparatus, intended primarily for use in an aerodynamic particle sizing system, for generating a pair of closely-spaced light beams, each having a thin, elongated cross-sectional shape. Particle sizes are determined by directing a particle stream through the light beams and measuring the times of flight of particles between the two light beams. The apparatus for generating the light beams includes a laser source and beam forming optics. In one embodiment, a first light beam is formed at the particle stream by a cylindrical lens. After passing through the particle stream, the first light beam is reflected and focused to form a second light beam at the particle stream that is displaced from the first light beam. The first light beam can be reflected and focused by a concave cylindrical mirror or, alternatively, by a flat mirror and a convex cylindrical lens.

Abstract: Powder dispersing methods and apparatus for use in an aerodynamic particle sizing system utilizing a time-of-flight measurement technique. The powder disperser provides an airborne stream of particles from a powder sample. The apparatus includes a container for holding the sample and having an outlet, a device for agitating the powder sample to produce a cloud of particles, a device for separating clusters of particles in the cloud, and an air flow through the container for carrying the cloud of particles to the outlet. The separating device preferably includes a small annular orifice in which air flow applies high shear forces to clusters of particles, tending to separate them. The agitating device preferably includes a jet of air directed at the powder sample. In one embodiment, the agitating device and the separating device are located in separate chambers of the container.