Advantech VariSifter VS1000, Operation/Setup Manual

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CHAPTER 1
WHAT IS SIEVING?
A simplistic definition of sieving is the
separation of fine material from coarse
material by means of a meshed or
perforated vessel. Professor Terence Allen
characterizes sieving as "The aperture of a
sieve may be regarded as a series of
gauges which reject or pass particles as
they are presented to the aperture."
(1)
This
theory was actually in practice during the
early Egyptian era as grains were sized
with 'sieves' of woven reeds and grasses.
The level of sophistication increased
with the rise of the industrial revolution
and the need for more sophisticated
methods for classifying material by their
particle size. As requirements for sized
material rose, technology in producing
uniform sieving media increased. Woven
wire cloth was introduced as an alternative,
providing greater accuracy and durability.
At present, this woven cloth is available in
a range of sizes from 125 mm (5")
openings to 20 micrometer openings.
All mesh sizes are covered by both national
and international standards.
The need for particle size analysis in the
finer size ranges (i.e. 38 micrometers and
less) prompted the development of the
electrodeposited sieve. These sieves,
sometimes called electroformed or
micromesh, are currently being produced
with openings as fine as 3 micrometers.
The mesh openings are extremely uniform
in both size and shape and maintain
exacting tolerances.
While the technology related to sieve
analysis has come a long way since the
reed sieves of ancient Egypt, few new
developments have come along since the
1940's. Professor Kurt Leschonski wrote
"Sieve analysis is one of the few methods
of particle size analysis which has escaped
modernization."
(2)
While the modernization
has not come in the actual hardware of
sieving, refinements in the application and
utilization of existing equipment has
proceeded.