Retsch AS 200 tap 30.025.0001 - Manual (Page 19)

08.01.2008 Retsch GmbH
19
Doc.Nr. D 98.025.9999
Working Instructions
Sieving aids
For materials which are difficult to separate we recommend the ad-
ditional use of sieving aids in the individual sieve fractions. For this
purpose balls of agate, rubber, porcelain or nylon brushes and
Vulkollan cubes can be used, depending on the mesh size of the
sieve and the preselected oscillation intensity. See also the table
below.
Make sure that the sieve fabric is not excessively expanded
through overloading with sieving aids since this will impair the
precision of your analytical sieves.
For recommended quantities of sieving material see the section
„Quantities of material to be sieved“
Overview table
Sieving aids Quantity per
sieve or sieved
material
Supplier Field of application Caution!!
Cubes of Vulkollan 5, 12x12 RETSCH, Haan With use of plane siev-
ing machines
Brushes 3 RETSCH, Haan
Plastic rings 3, various dia.
Small brushes With hand sieving
Highly dispersed silica
(Aerosil) 0.5 to 2% Degussa, Ffm With fine, sticky,greasy
sieved materials and
materials which are
electrostatically charged Before adding check usability and
compatiblity
- - Aluminium oxide 0.5 to 1% Degussa, Ffm
- - Talcum With crude rubber and
rubber powder
Drying With very wet / very
damp sieved material
Pass dry warm air through the
set of sieves With hygroscopic sieved
materials
TAP function With fine, easily sticking
sieved materials which
fall through the meshes
only with difficulty A TAP function is built into the Tap
Sieving Machine AS 200 tap, which
can be switched off as required.
Quantities of material to be sieved
A set of sieves required for sieve analysis is made up of a number
of analytical sieves arranged one on top of the other with increas-
ing mesh size.
In order to guarantee quick fractioning with an exact result the
quantity of material to be sieved must be adapted to the sieve di-
ameter and the nominal diameter of the openings.
Guide values for this are given in the respective standard specifi-
cations for sieve analysis, e.g. according to DIN 22019/1 the fol-
lowing maximum added quantities are recommended:
Nominal diameter of
sieve openings
Material quantities in dm3 for
200mm diameter
8 0 . 5 0 0
3 . 1 5 0 . 3 0 0
1 0 . 1 4 0
0 . 5 0 . 1 0 0
0 . 2 0 . 0 6 0
0 . 0 6 3 0 . 0 3 5
0 . 0 2 0 0 . 0 2 0