Retsch AS 200 control - natural frequency - Manual (Page 20)

Retsch GmbH 20
Wet sieving
In most cases dry sieving is possible. However,
with some materials the adhesive forces between
individual particles can cause difficulty. These
problems can be overcome by adding a liquid,
preferably water, during the sieving process (if the
accessories mentioned in the section on sieving
aids are not successful). However, wet sieving is
possible only if the materials to be sieved do not
swell, dissolve or change in any other way in the
sieving liquid.
Required accesories
Clamping cover with spraying nozzle for the
corresponding sieve diameter.
Intermediate rings with vent holes.
Collecting bottom container with water outlets for
the corresponding sieve diameter.
Preparation
Position your AS 200 control near to a water
outlet point.
Connect the spraying nozzle of the clamping
cover to a tap by means of a hose.
Connect the outlet of the collecting bottom
container to the water outlet point or a suitable
collecting vessel.
Procedure
Use the intermediate rings with vents.
Add the solid material as a suspension.
Adjust the pressure of the added liquid (water)
only to the extent that the sieving surface is
completely sprayed.
It is advisable to use a dispersing agent. This
reduces the surface tension of the sieving liquid.
If it is difficult to form a slurry with the material
or to obtain exact separation, the individual
fractions should be sprayed one after the other.
After the sieving process the fractions are
transferred from the individual sieves to a
suitable filter (e.g. filter paper) and dried in a
drying oven at 80°C.
The sieves are then cleaned in an ultrasonic bath
and also dried in a drying oven (without the
seals).
Do not exceed the maximum drying temperature
of 80°C.
Never operate your AS 200 control directly in water.
Danger through current surge.
During wet sieving always operate your AS 200 control
connected to a mains socket protected by an FI
protective (safety) switch.