Quality confirmed by ISO 9001 cert.
What do you want to measure ?
Our instruments presented accoriding to measurement type and range.
Infoline: +48 22 666 93 32
Optical - electronic simulation of sieve analysis of micro-grains bigger than 0,5 μm
With modern technologies the micro-grains and their proper characterization become a crucial issue in the construction sector. At this moment it’s common to use traditional sieve measuring method , that especially for micro-grains, is arduous and not enough accurate.
Nowadays, the measuring technique introduces the new technologies for measurements of micro-grains by use optical-electronic sensor. One of the methods is based on counting and measuring of particles in parallel light beam. It’s the most useful method of grain-size measurements and it can replace sieve analysis by simulating it and giving exact results as sieve analysis. Simulation of sieve measurements can start from 0,5 μm, what is hardly possible for traditional sieve analysis. There are also no limitation for this method for bigger grains in whole range that is used in traditional sieve analysis.
A typical instrument for grain-size determination by using method mentioned above is IPS
U analyser described in the Internet at www.kamika.com
REASON FOR SELECTED SPECIFIC MEASURING METHOD
Among modern optical-electronic grain-size measuring methods the one that use measurement in parallel beam is the most suitable one. In this method any beam emitter can be used and the measuring space is limited only by construction of optical systems. The air is the main mean of transportation during feeding in the method. For suspension substances also water or water solutions can be used if the construction of analyser would be different.
The measurement in the air of dry substances simplifies preparation and making of measurements. Such measurements can be made for bounding or moist materials. As it’s shown at Figure 1 the measuring sensor, that has basic and compact construction, consists of light emitter , optical system A and B and photodiode . The light from the emitter  goes through optical system A, where the parallel beam  is formed. The beam is limited by aperture that can be up to several hundreds μm thick. The light beam  creates the measuring zone till the optical system B. The optical system B focuses the beam at the photodiode .
If there is no particles in the measuring zone, at the output  from preamplifier there is direct current as a result of lighting the photodiode. If there are any particles in the measuring zone, at the output  there is change in voltage (an impulse) as a result of light scattering by particles. For sub-micron particles the light scattering effect is modified by diffraction.
The particles are always univocally situated in measuring zone because of the air or the water flow. The particle goes through the instruments by its smallest size and the biggest profile along the move direction. There is exact dependence of the maximum dimension of the grain upon the electrical impulse amplitude on the output  and of the minimum dimension of the grain upon the
impulse width. The impulses, that are measured and counted, univocally, exactly and reproducible determine set of particles. The impulses can be saved in electrical units as convener channels in the computer. The set of particles, that is saved in the computer as statistical grain-size distributions, after recalculating to volume distribution can be compared to real measurement according
to sieve analysis. As it’s shown at Figure 2 thanks to above comparison the special characteristic can be calculated. This characteristic is sieve calibration for optical-electronic measuring instrument.
The calibration is dedicated to specific substances, that consist of typical by shape particles, that can vary by size. If there are grains that shape vary, another calibration should be made. Based on that the library of sieve calibrations can be built. From the calibration library, saved in the computer, the right one can be chosen for measured material. Thanks to the calibration the grain-size distribution saved in electrical unit can be recalculated the real results. In this way the sieve