Retsch AS 400 - Manual (Page 21)

06.11.2012
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Retsch GmbH 21
Working instructions
Sieving aids
When dealing with material that is difficult to separate, we recom-
mend the additional use of sieving aids in the individual sieve frac-
tions. Depending on the width of the sieve meshing and the prese-
lected vibration intensity, pearls made of agate, rubber, porcelain or
nylon bristles and Vulkollan cubes may be used. Also refer to the
table below.
Ensure that the fabric of the sieve is not overstretched by over-
loading with sieving aids as this would have a detrimental effect
on the precision of your analytical sieve.
Refer to the paragraph on sieving material quantities for the rec-
ommended material volume.
Overview table
Sieving aids Quantity per
sieve or charge
Supplier Area of use Caution !!
Vulkollan cubes 5 pcs., 12x12 RETSCH, Haan Planetary sieving ma-
chines
Bristles 3 pcs. RETSCH, Haan
Plastic rings 3 pcs., various Ø
Brushes Manual sieving
Highly dispersed silicic acids
(aerosil) 0.5 to 2% Degussa, Ffm Materials to be screened
are fine, sticky, fatty
and electrostatically
charged Check applicability and compatibility before
adding!
-  - aluminium oxide 0.5 to 1% Degussa, Ffm
-  - talcum Latex and rubber pow-
der
Dry Materials to be screened
are very wet or damp
Guide dry, warm air through the
sieve set Hygroscopic materials to
be screened
Intermittent sieving RETSCH, Haan Materials to be screened
are fine, stick easily, or
only fall through the
mesh with difficulty Intermittent switching (changes direction of
rotation) is built into the AS400 flat-bed
sieving machine and can be switched on, if
required.
Sieving material quantities
The sieve stack required for sieve analyses is composed of analyti-
cal sieves arranged one above the other, with progressively larger
holes towards the top, plus the base pan.
To ensure fast separation with exact results, the quantity of the
material to be screened should be adapted to the sieve diameter
and the nominal size of the openings.
The relevant standards on sieve analysis (e.g. DIN 22019 / part 1)
state guideline values in which the following maximum charge
quantities are recommended:
Nominal widths of the screen
openings
Material quantities in dm3 at
400 mm sieve diameter
1 8 4 , 0 0 0
1 0 2 , 4 0 0
8 2 , 0 0 0
6 , 3 1 , 6 0 0
5 1 , 4 0 0
3 , 1 5 1 , 2 0 0
1 0 , 6 0 0
0 , 8 0 , 5 0 0
0 , 5 0 , 4 0 0
0 , 3 1 5 0 , 3 2 0