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Flow additive: powdered substance added
to the sample to reduce agglomeration,
neutralize static charges and improve the
flow characteristics of the sample. Common
additives are fine silica, activated charcoal,
talc, and other commercially produced
natural or synthetic substances. Generally,
the additive is pre- screened to a known
average particle size, blended with the
sample (approximately 1% additive by
weight)
and
then
additives value removed from the reported
data.
Frame: a rigid sidewall used to form the
body of the testing sieve. Common depths
are 50.8 mm (2" full height) for 8" sieves
and 25.4 mm (1" half height). Special
application sieves of other depths are also
in use.
Mesh: screening medium with openings of
uniform size and shape made of woven,
punched or electrodeposited material.
Pan: stamped or spun receiver of materials
passing through the finest sieve.
CHAPTER 4
The U.S. Standard Sieve Series is a
metric system based series first suggested
by the American Society for Testing and
Materials in 1913. The opening sizes in this
sieve series are in the ratio of the fourth
root of two. This numerical relationship was
first suggested by Professor P .R. Rittinger,
a German researcher, in 1867.
In the fourth root of two series, every
opening size is 1.189 times the opening
size
of
the
next
screened
with
the
smaller
sieve.
This
Skirt: section of test sieve below the sieve
mesh that allows for mating or nesting of
the sieves in a test stack.
Support
mesh:
mounted under fine sieve cloth in a test
sieve to provide extra strength. This is
widely used in wet sieving operations to
protect
the
fragile
Frequently called backing cloth or rolled
backing cloth.
Test Sieve: screening medium (mesh)
with openings of uniform size and shape
mounted on a rigid frame, usually for
laboratory testing or small scale production
applications. The frames can be made of
various materials, the most common of
which are brass and stainless steel in a
cylindrical configuration, having a diameter
of 3", 5", 6", 8", 10", 12" or larger.
Wet sieving: the separation of fines from
the coarse portion of a sample while
suspended
in
introduced to a testing sieve. The liquid
medium is used to negate static charges,
break down agglomerates and lubricate
near-size particles. After the fines have
been
washed
through
residue is oven-dried and re-weighed.
SIEVE SPECIFICATIONS
-Domestic and International
relationship continues into sieve opening
area measurement. The U. S. Sieve Series
provides that the area of each sieve
opening size is 1 1/2 times the area of the
preceding sieve size.
By using every other sieve in this
number series, the relationship becomes
based on the square root of two (1.414),
with the area of the opening being twice
that of the preceding sieve size. Thus, by
skipping two sizes, you create an area ratio
coarse
sieve
fine
sieve
an
aqueous
solution
the
sieve,
cloth
cloth.
the
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