![]() ![]() The scattering pattern produced by a single spherical particle consists of a series of light and dark concentric bands that decrease in intensity with increasing radial position.Ĩ Contd… 3). This method is based on diffraction scattering only, and it won’t take into the consideration of others like absorption, refraction and reflection, where as Mie scattering will. There are two principal optical models for analysis of diffraction spectra: Fraunhofer Scattering, Mie Scattering. This method has become the preferred standard in many industries for characterization and quality control. 2) A suitable detector Eg: A slice of photosensitive silicon with a number of discrete detectors.Ħ Laser diffraction (LD) is a method used for particle size measurement that is based on the properties of particles to scatter light. Instruments consist of: 1)A laser as a source of coherent light of known fixed wavelength. Principle: The method relies on the fact that diffraction angle is inversely proportional to particle size. Microscopy: It is not suitable as a quality or production control technique.ĥ LASER DIFFRACTION: Applicable range: 0.1-3000 μm The method requires calibration standards which are expensive, difficult to measure emulsions and Porous particles give significant errors. Electrozone sensing: This technique was developed in the mid 1950’s for sizing blood cells. Sedimentation: This has been the traditional method of measurement in the paint and ceramics industry and gives relatively low answers! The applicable range is 2-50 microns. Sieves: This is readily usable for large particles such as are found in mining.Not possible to measure sprays or emulsions. Particle size distributions can take on a large number of shapes and sizes.2 Different methods adapted for particle size analysis:ģ Methods applied for the size range of particles:. ![]() These applications are usually in the colloid region and are measured with electron microscopes or dynamic light scattering devices There are applications in which the particles may be very small, in which they may be specified in nanometers. Most measured particles fall into this range. The most common designation is micrometers or microns. Particle size is specified in fractions of a meter.Presentation and many more on other topics Visit Contact us directly at the Download Center to find this recorded Vary measurement and calculation parameters Watch for finer particles being created with increasing energy Watch for no change in coarsest particles with changing energy Watch for finer “particles” appearing with increasing concentrationĭetector Number (higher detector numbers for smaller particles) Multiple peaks can be better described individually All rights reserved.īetter to use D(4,3) when you want spec. Poor precision is the result of either a poor Statistics describing the distribution must… See Technical Note 156 in Download Center for more info 1 STD DEV +1 STD DEV = distribution mean Smaller than this diameter smaller than this diameter Half are smaller than this diameter half are larger than this diameterġ0% of the particles are 90% of the particles are Remember: D is sensitive to large particles Will emphasize the detection of large particles Monitoring the D value in your specification This is called the D - the number meanĭ which is often referred to as the Volume Mean Diameter What is the average size of these spheres? Microscopes or by dynamic light scattering. Measured in nanometers, typically by ultra The most common designation is micrometers or Spherical: Regular-shaped, unity aspect ratioĪspect ratio: Breadth / length OR Length / breadth Granular/Blocky: Irregular-shaped, low aspect-ratio Number-based diameter Calculated from number dist.Ĭumulative% on diameter % of distribution finer/coarserĭiameter on cumulative% Size at which a specified % of Volume-based diameter Calculated from vol. Surface diameter: Diameter of a sphere having the sameįrequency% / q% / Amount of each size by volume Volume diameter: Diameter of a sphere having the same Monodisperse: All particles have same size Measures particle projection no shape assumption Understanding Your Particle Size Analyzer Resultsĭecoding the Acronyms and Finding Insights ![]()
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