- THE MAGAZINE Principles of OperationIn contrast to other
methods, air jet sieving is usually carried out with only one
sieve. The sieve is placed on the unit with the sample material
and covered with a lid. A powerful industrial vacuum cleaner
generates a strong jet of air, which disperses the particles on
the sieve through the slotted nozzle rotating below the sieve
mesh. With each rotation, the particles are dispersed and
distributed over the complete sieve surface. The jet of air
causes a continuous new orientation of the particles on the
sieve surface. Particles with sizes smaller than the sieve
apertures are sucked in by the vacuum cleaner or-if the optional
cyclone is used-collected in a laboratory bottle. When using
sieves 25 mm high, the inflowing air causes the particles to
impact on the lid, which helps to destroy agglomerates. The
nozzle rotating below the sieve usually has a fixed speed, but
varying this speed can be helpful. Sensitive sample materials,
for example, should be sieved with a low s