Retsch AS 450 control - Handbuch (Seite 31)

Working instructions
31
7.2 Overview Table
Sieving aids Quantity for
each sieve /
material to be
sieved
Supplier Area of Application Note!!
Rubber balls 5 pcs., Ø20 mm RETSCH, Haan with fine, dry materials that are
difficult to separate and the use of
projection sieve shakers When mechanical sieving aids are
used, there is a danger that soft
materials
may disintegrate and
damage can occur to fine sieve
meshes!
Agate balls 10 pcs., Ø10 mm RETSCH, Haan
Hard porcelain balls approx. 10gr., Ø2
mm RETSCH, Haan
Vulkollan® cube 5 pcs., 12x12 RETSCH, Haan when using planetary sieve
shakers
in manual sieving
Brushes 3 pcs. RETSCH, Haan
Plastic rings 3 pcs., various
diameters
Small brush
highly dispersed silicic acid 0.5 to 2% Degussa,
Frankfurt-on-Main with fine, sticky materials that
contain
fat and are
electrostatically charged
Before adding, check usability and
compatibility!
- “ - Aluminium oxide 0.5 to 1% Degussa,
Frankfurt-on-Main
- “ – activated carbon
-

- talcum with crude rubber and rubber
powder
Degreasing When the material being sieved is
very greasy The material being sieved and the
grain size must not be changed by
the solvent during degreasing or by
the temperature and air during
drying.
Drying When the material being sieved is
very wet/very damp
Guide dry, warm air through
the sieve stack When the material being sieved is
hygroscopic
Send water vapour through
the material When the material being sieved is
coarse
and electrostatically
charged
First screen with the fine
sieve and then with the
coarse sieve. If it is important to prevent
contamination
from other
mechanical aids, such as e.g.
rubber balls.
The coarse material works like a
mechanical sieving aid (balls) on the
fine sieves.
Intermittent sieving RETSCH, Haan for fine materials that stick easily
and drop only with difficulty
through the shaker. Intermittent switching is built into
most projection sieve shakers and
can be switched on as required.
7.3 Sieving Sample Quantities
The stack of sieves required for the sieve analyses consists of test sieves arranged
one on top of the other in ascending order of aperture size as well as the collecting
pan.
To ensure quick fractioning with an exact result, the quantity of the material being
sieved must be adapted to suit the sieve diameter as well as the nominal diameter
of the openings. Guidelines are obtained in the respective standards for the sieve
analyses.
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