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 – 10o cm³ are a clearly higher as with a wet dispersion.

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.

One of the main differences between dry and wet dispersion is based on the fact, that it is almost a solely mechanical dispersion in an air flow. Thereby, with a dry dispersion, a sensible measurable particle size and the associated complete primary particle dispersion is typically at approximately 1 - 10 µm. Depending on the material and its properties, below this range an incomplete dispersion can be expected. The utilization of the dry dispersion makes sense in areas where a wet dispersion in water or solvents has to be ruled out.

The dispersion pressure is set with the assistance of SOPs with the software MaS control and then is carried out automatically. Measurement processes can therefore be freely programmed and the entire measurement takes place completely automatic.

• Fast measurement of powdery samples in an accelerated air flow
• For sample volumes from less than 1 cm³ to approx. 100 cm³
• Efficient degradation of agglomerates with a special annular gap Venturi nozzle
• No impact areas – protection against comminution of the particles
• Perfect sample feeding with high-frequency feeder
• Automatic computer-controlled adjustment of the dispersion pressure
• Fully automatic measurement processes freely programmable
• Especially fast and easy to clean
• Multifunctional exhaust system - for automatic sample exhaust during measurement and for manual cleaning of the feeder after measurement
• Conversion kit (order no. 22.8670.00) to use the Dry Dispersion Unit as a Falling Chute for measuring agglomerates of dry powder or for determining particle size distributions of free-flowing, coarse-grained materials, which should be measured without dispersion.

Ideally, for the operation of the Dry Dispersion Unit, is an oil-, water- and particle-free supply of compressed air with a pressure of at least 5 bar and a flow rate of at least 125 l/min. An external exhaust system is necessary to vacuum the sample material, which can be ordered as a FRITSCH accessory together with the instrument.

In order to use the FRITSCH Dry Dispersion Unit you will need the ANALYSETTE 22 MicroTec plus Measuring Unit (Order No. 22.8400.00). 

Additional detailed information about the Measuring Unit MicroTec plus here.