Malvern particle sizer

The measurement size range of the Malvern particle sizer is dependent on the focal length of the Fourier transform receiver lens. Each detector-lens combination corresponds to approximately a 100 to 1 droplet size range. For example, a 100-mm lens gives a droplet size range of 2-197 pm, whereas a 300-mm lens corresponds to a droplet size range of 5.8-564 pm. Lenses of 600, 800 or 1000 mm in focal length may be used for coarser sprays. With a proper choice of lens, most practical sprays can be readily measured. 

Figure 6.5. Schematic of optical arrangement in a Malvern particle sizer.

The Malvern particle sizer is one of the most widely used, most effective, simple, and reliable methods commercially available for rapid measurements of ensemble characteristics of a spray. It is able to handle high droplet concentrations. It is easy to use and does not require comprehensive knowledge of its basic principles for operation. The primary advantage of the system is the speed of data acquisition and analysis. In addition, measurements of droplet size distributions can be made at any droplet velocities due to the fact that the diffraction patterns generated by droplets are independent of the... 

The Malvern Particle Sizer 3600 c uses light scattering measurements to infer the CSD. The device has a He-Ne laser that illuminates the particles suspended in a stream that is moving continuously through a flow cell. The diffracted light is then focused... 

Experimental Analysis. The most reliable process measurement is the oscillator frequency from the PAAR densitometer. Along with the frequency, the temperature is also measured ( 0.05 C). These two states are used to interpolate the solute concentration. CSD weight percent information and obscuration measurements were obtained from the Malvern Particle Sizer. Approximately 500 concentration data points and 200 CSD and obscuration measurements were recorded during a run of about 80 -100 minutes. Therefore, the dynamics of the system were well monitored, i.e., the time constant of the crystallizer is much larger than the sampling time. We have performed 25 experimental runs. This section summarizes the analysis of a single, typical experiment. 

The porosity of the flocculated suspensions in the experiments is always smaller than 0.005. This value is measured with a Malvern Particle Sizer type 2200 when very high coagulant doses were used. Therefore, the correction for the sedimentation velocity is always smaller than 1.02. 

Kouzelis, D., Candel, S. M., Esposito, E., Zikikout, S., Particle Sizing by Laser Light Diffraction Improvements in Optics and Algorithms,Part Charact, 1987,4, 151-156. Bayvel, L. P., Knight, J., Roberston, G., Alternative Model-Independent Inversion Programme for Malvern Particle Sizer, Part Charact, 1987,4,49-53. 

Grinding was performed using Retsch ball-mill. Particle size distribution was measured using Malvern (Mastersizer) laser particle sizer. BET surface area measurements were carried out using ASAP (Micromeritics) surface area analyzer. 

Liquid carbon dioxide (purity 99, 95 Vol %) was undercooled (W2) to avoid cavitation in the membran pump (P). After the compression to pre-expansion pressure, the fluid is heated to the extraction temperature (W3). The supercritical fluid loaded with anthracene leaves the extractor (V = 0,6 1). With a additional heat exchanger (W4), the solution is heated to pre-expansion temperature. In the separation vessel, the supercritical solution is expanded through a nozzle. The expanded gas will be condensed (Wl) and recompressed or let off. After the experiment, the separation vessel is opened and the particles were collected. The particle size is measured by laser diffraction spectroscopy (Malvern Master Sizer X). 

Malvern High Performance Particle Sizer (HPPS) combines high sensitivity with a high concentration capability using dynamic light scattering with back-seatter optics. The HPPS covers the size range 0.6 nm to 6 pm at concentrations from 0.00001 vol% to 20 vol% at speeds up to 20°/s. 

Ciurczak and associates " reported a NIR method of determination of particle size of pure, granular substances. The method is based on theories of reflected light, in which reflectance increases as the particle size decreases. The reference method was a low-angle laser light-scattering (LALS) particle sizer (Malvern). The researchers found linear results for particles above 85 mm, but less accurate results for smaller particles. 

The best method of the determination of the particle size distribution of the different crospovidone types is the light diffraction measurement (e.g. Malvern Master Sizer, see Fig. 63 and 64). The particle size distribution of normal crospovidone also can be measured by sieving or air jet screening. In this dry sieving method more than 50 % of the particles are coarser than 50 pm without any swelling. Therefore even with this dry method it corresponds clearly to the definition of Type A of the Ph.Eur. monograph. 

The particle size distribution of micronized crospovidone can be measured as suspension in water or cyclohexane by a Malvern Master Sizer and there is no significant influence of the solvent. If almost all particles are finer than 50 pm it is classified as Type B of Ph.Eur. 

Fig. 63. Particle size distribution of the normal grades of crospovidone available in the market (Method Malvern Master Sizer)...

Figure 18 Principle of operation of a Fraunhofer diffraction laser particle sizer. (With permission of Malvern Instruments, Inc.)...

The efficiency of homogenization may be assessed by microscopic examination or more effectively by a particle sizer, e.g. Malvern Mastersizer. 

Measurement of Size of Microcapsules. We measured the size of poly(L-lysine-a/r-terephthalic acid) microcapsules in various buffer solutions by the usage of a particle sizer (Malvern System 3601). About 15000 microcapsules are dispersed in 1 ml of suspension medium. 

Mechanical stability of dispersions was determined using a laboratory centrifuge with rotational speed of 3700 rpm. Particle size, particle size distribution and zeta potential of the dispersions was determined using Malvern Zeta Sizer 4 equipment. Minimum film formation temperature (MFFT) was measured using a Coesfeld apparatus. 

Taking advantage of the capabilities offered by the Malvern Zeta Sizer apparatus the computer analysis of total volume of smaller and bigger particles (it may be noticed that on the curves showing particle size distribution in Figure 6.26 that there are two peaks visible). Results are ... 

One way to increase the range of measurement is with the use of light scattering (Doppler electrophoresis) to determine particle velocities. Such methods are used in contemporary commercially available analytical particle electrophoresis apparatus, such as the Malvern Zeta-Sizer and the Coulter DELSA 4440 . In addition, in recent years, image analysis methods have been used to determine particle velocity in systems employing traditional optical microscopy to observe the particles (7). 

In a couple of particular papers, the application of LD particle sizer to measure the size distribution of micro-bubbles are mentioned. Couto et al. [44] performed micro-bubble size distribution measurements by the laser diffraction technique. It was concluded that the size distribution of micro-bubbles generated for the dissolved air flotation process could be assessed on a fast and reliable way by the application of the laser diffraction technique. The micro-bubble size distribution was measured by the Mastersizer 2000 SM equipment from Malvern Instruments, UK. The instrument specifications state that analysis in the particle range from 0.1 to 2000 ttm is possible, and the data interpretation computations could either be performed by use of the... 

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