Dry dispersion is ideal for dry, free-flowing and non-sticking materials. Especially coarse material can be measured with it very well and easily.
With the dry dispersion unit the sample material is transported continuously via a vibratory feeder through the measuring cell via an air flow, measured and then vacuumed off. The needed sample material amounts of < 1 100 cm3 are a clearly higher as with a wet dispersion.
The dispersion process
With a high-frequency feeder the sample material is continuously transported over the funnel-shaped opening of the dry measuring cell and then drops in the actual dispersion area. In an annular gap Venturi nozzle the powder is accelerated and passes with a high speed through the nozzle channel and the measurement of the particle size distribution in the laser beam takes place directly behind it. Then it passes a zone with aerodynamic wave generation at the nozzle outlet. The by the high turbulent current caused strong shearing forces, as well as blows between the particles lead to the breakdown of the agglomerates. No impact areas in the flight path of the particles exist in order to prevent soft sample materials from being ground during the dispersion process.
Compared with the wet dispersion is the dry dispersion not as efficient due to chemically-physical as well as rheological material properties of the sample material.