Laser Diffraction Particle Analyzer

The Malvern Analyzer, manufactured by Malvern Instruments Ltd., United Kingdom, is a spatial sampling device that utilizes the principle of light scattering to measure drop size. A drop causes laser light to scatter through an angle dependent on the diameter of the drop. The scattered light intensity is measured using a series of semicircular photo diodes. Theoretically, the distance of the individual photo diodes from the centerline of the laser and the light intensity functions are all that are needed to calculate the drop size distribution.

A curve-fitting program is used to convert the light intensity distribution into any of several empirical drop size distribution functions. The Malvern 2600C analyzer measures sizes in the range of 5 to 1800 μm. The instrument includes self-diagnostics to facilitate identification of potential error sources. These instruments are aligned and calibrated periodically using the calibration verification procedure performed in accordance with ASTM Standard E1458-92.