PARTICLE ANALYZER SYSTEMS

A simple, affordable device is necessary to encourage more accurate particle analysis methods in order to verify relative accuracy and enjoy the benefits. One developed in the HOCKMEYER laboratory, The HPAS-2000 with MicroPart™, can do this by producing representative statistical data of the particle size distribution band of solids or solids dispersed in liquids.

The HPAS consists of a microscope, a digital camera, and a computer with custom software. After placing the sample under the microscope, multiple pictures are taken and analyzed for individual particle size. The particles are then bi-dimensionally classified, counted and graphed for final printout.

Alternatively, laser technology can offer three dimensional particle analyses, which may further enhance accuracy. Both two and three-dimensional measuring techniques are limited in their ability to accurately measure the size of a non-spherical particle. Most industrial particles measured are not spherical. Our observations have indicated only very minor differences in data generated between the two technologies. However, both offer quantum leaps in product quality predictability compared to a hand held grind gauge.

CORRELATION BETWEEN PARTICLE SIZE AND QUALITATIVE PROPERTIES.

Our research indicates a positive correlation between particle size and qualitative properties of the dispersion.

Controlling the dispersion by following a particle distribution band can be challenging. A wide variety of factors can influence the uniformity of the band but for the purpose of this discussion we shall segment into two broad areas and focus on the second.

Chemical: Instances where particles bond more or less intensely because of the influence of a foreign substance. Example: Coalescing and dispersing agents.
Mechanical: Instances where particles bond more or less intensely because of the influence of a foreign force. Example: Shear
Energy uniformly applied to a wide particle distribution band tends to narrow and shift the band as a function of time. The largest agglomerates break apart into smaller agglomerates and continue their down-sizing trend until the energy required to make them even smaller is no longer sufficient. An increase in energy input will continue the reduction trend until the next stabilization level is reached.

The continual addition of uniform energy input to the dispersion will challenge the ingenuity of the machinery designer to control the transfer of shear rate into shear stress without exceeding temperature and stress limitations of the dispersion.

Scale should be driven more by the measurable duplication of particle distribution band per unit of time (performance) and the avoidance of subjective variables. Laboratory equipment can be designed to duplicate production equipment using measurable baselines. Machine manufacturers can incorporate the common baseline of particle size distribution into the performance data on dispersion equipment using published, standardized formulas that can become universal performance standards.

Users should be educated in the proper techniques of scale. Equipment manufacturers can focus more on establishing uniform standards of scale and milling consistency rather than impressing users with the performance of a lab mill that cannot be duplicated in the factory. Users should not be left to determine what the manufacturer might have had in mind when the machinery was designed.

The standardization of measure via these new technologies will help companies compete in an ever more competitive industry. In particular, the incorporation of particle size analysis as a measure of quality and a basis for scale.