Particle vision measurement

Figure 2. Particle Vision Measurement (PVM ) identifying crystalline DBX-1.

PVM Particle vision measurement Particle size and morphology... 

Su et al. [24] studied the polymorphic transformation of n-mannitol by in situ Raman spectroscopy coupled with FBRM (focused beam reflectance measurement) and PVM (particle vision measurement). In this way, relationships between fine particles and metastable-form dissolution, and also between coarse particles and stable-form crystallization, could be defined. The different polymorphs were identified by Raman spectroscopy. FBRM provided a method for independently verifying these observations. PVM, in turn, verified the data interpretation strategy employed for FBRM. 

In addition to the characterization of the product, the characterization of the system during the crystallization process may be very important as it may help to ensure a stable and controlled crystallization process leading to material of the desired quality. A number of methods have been adapted for online use. These include XRPD, IR, ultrasound absorption, and Fraunhofer diffraction. The most commonly and conveniently used ones are turbidity, NIR, Raman, FBRM (focused beam reflectance measurement), and PVM (particle vision measurement). 

Typical plant reactors do not allow for good visual monitoring because limited observation is possible from the top of the reactor. Recent techniques, such as the Mettler Toledo-PVM (Particle Vision and Measurement), enable in-process imaging. 

There is great interest in the electrical and optical properties of materials confined within small particles known as nanoparticles. These are materials made up of clusters (of atoms or molecules) that are small enough to have material properties very different from the bulk. Most of the atoms or molecules are near the surface and have different environments from those in the interior—indeed, the properties vary with the nanoparticle s actual size. These are key players in what is hoped to be the nanoscience revolution. There is still very active work to learn how to make nanoscale particles of defined size and composition, to measure their properties, and to understand how their special properties depend on particle size. One vision of this revolution includes the possibility of making tiny machines that can imitate many of the processes we see in single-cell organisms, that possess much of the information content of biological systems, and that have the ability to form tiny computer components and enable the design of much faster computers. However, like truisms of the past, nanoparticles are such an unknown area of chemical materials that predictions of their possible uses will evolve and expand rapidly in the future. 

Danfoss QueCheck Vision System performs a continuous analysis directly from the production line, typically at 0.5 s intervals. The final results of the measurement are available after 100-300 frames so that an equivalent sieve analysis is completed every 3 min. The particle size distribution is documented via an interface with database and printer. The material is fed in a fine stream, by means of a vibratory feeder, past a vision camera that calculates the size distribution as it falls. The system has been applied to measuring the size distribution of sugar crystals. Online image processing has also been applied to monitoring granule size distribution and shape in fluidized bed granulation [150]. 

The instrument has also been used for size analysis of sugar crystals from 40 pm to several mm in size. By means of a vibratory feeder, the sugar is fed in free fall, past a vision camera and sized every 5s. The final result of the measurement is available after 100-300 frames and documented via an interface with a database and printer. Measured data includes particle count and size or projected area. 

It was Hans Rumpf in the 1950s who had the vision of property functions, and who related changes in the functional behavior of most particle processes to be a consequence of changes in the particle size distribution. By measurement and control of the size distribution, one could control product and process behavior. 

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