Test Sieve & Screen Tray Verification & Services - Gilson SS-20 Operating Manual

• Brass Frame with Stainless Steel Cloth is a popular
choice that offers extended service and cost
effectiveness.
• Brass Frame with Brass Cloth is economical for
light- duty applications. Coarse-series sieves are not
available with brass cloth.
Backing Cloth
Back-up cloth prevents sagging or tearing of expensive fine
stainless steel mesh. Unsatisfactory service life from a sieve
would suggest replacement by a sieve built with backing
cloth. To order, add the code "BU" to the model number
of the sieve. These sieves are made-to-order, have longer
delivery times and are non-returnable.
Pans and Covers
• Pans collect fines at the bottom of the sieve stack.
Extended-Rim pans are also available to insert into
the middle of a stack, allowing two samples to be
tested at once.
• Covers are not necessary with most Gilson sieve
shakers, but may be needed if using a different
shaker or shaking by hand. The Cover-with-Ring has
a wire finger loop in the center to facilitate removal.
Gilson Sieve Verification Services
Gilson Verification can be performed on any test sieve or
Gilson screen tray, used or new. These services are ordered
by specifying the appropriate model number given in our
listing for Test Sieve and Screen Tray Verification and
Services. An optical comparator with NIST traceable
calibration measures opening sizes and wire diameters on
each sieve, and a statistical analysis assures the standard
deviations are within ASTM or ISO requirements for
Inspection or Calibration grades. Sieves, trays, or wire cloth
units are not included in the purchase price of the
verification services. Because wire cloth stretches, sags, or
tears, and abrasive materials can reduce wire diameters, a
verification process should also be set up to regularly verify
that working sieves still meet the specifications. These
measurements can be taken directly using calipers or an
optical comparator, by testing with Standard Reference
Materials, or by returning to Gilson for Re-Verification. To
verify used sieves, contact a Gilson customer service
representative for shipping instructions.
Standard Reference Materials (SRM's)
Sieve Reference Materials are precision glass beads or
powders for performance testing of sieves. They are
traceable to the National Institute of Standards and
Technology (NIST), or European Community Bureau of
Reference (BCR). SRM's fit easily into internal quality
programs following guidelines in ASTM E 2427, Sieve
Acceptance by Performance Testing. User-Prepared
Reference Materials can also be utilized under E 2427
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in the same manner as SRM's. Because user materials are
non-standard, they are not traceable and require much more
handling. In addition, the user must determine acceptable
tolerances for statistical analysis.
Sieve Shakers
The proper sieve shaker saves considerable time and effort,
and yields superior accuracy, consistency, and repeatability
compared to manual shaking methods for particle sizing.
Effective agitation lifts all particles off the sieve cloth,
reorients them, and allows them to be repeatedly "tried" to
different openings at different angles. Careful review of
shaker specifications allows optimal choices for different
materials and applications. Greater sample volumes and large
particle topsize may indicate selection of Gilson Test
Master®, Testing Screen or Porta- Screen® models for
efficient processing.
9.2 Test Sieve & Screen Tray Verification &
Services
There have been extensive revisions to the newest version of
ASTM standard E 11, Specification for Wire Cloth and Sieves
for Testing Purposes. Gilson is leading the way in educating
our customers about the new specification and making these
new products available. The new specification affects all test
sieves, screen trays, and wire cloth, and changes the way the
mesh openings are evaluated by looking at the statistical
distribution of aperture sizes, rather than just the average
opening sizes. In addition to a more accurate and reliable
system of evaluation, the new system also allows
compatibility with ISO 565 and 3310-1 requirements. There
are now three grades, or classes of ASTM or ISO test sieves
available; Compliance, Inspection and Calibration.
Compliance Test Sieves are manufactured with wire cloth
that has been inspected and measured in roll or sheet
quantities prior to being cut and mounted in the individual
sieve frames. Opening sizes are not measured in individual
sieves. Each Compliance sieve is supplied with a certificate of
manufacturing compliance, but no statistical documentation
is given. Compliance sieves are designed for applications
where a basic, reliable degree of accuracy and repeatability
are sufficient.
Inspection Test Sieves have a specified number of
openings measured in each sieve after the cloth is mounted in
the frame. There is a 99% confidence level that the standard
deviation of these openings is within the maximum allowed
by ASTM. Inspection Sieves are a good choice in applications
where accuracy and repeatability are critical. Each Inspection
Sieve consists of a Compliance Sieve with added Inspection
Sieve Verification service.
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