Endecotts ASTM Compliant Sieves
Several standards organizations have established procedures for certifying woven wire mesh (also know as woven wire cloth) test sieves.
The diameter and construction of the frame are one element of the specification. These measurements are fixed and easily understood. However, several factors, including the weaving process, affect the precision of the openings over the surface of a section of woven wire mesh. Consequently, standards institutions such as ASTM and ISO give particular emphasis to establishing acceptable limits of opening size in mesh used for test sieves.
Available in the following options:
For examples of these detailed specifications and techniques, we refer to the technical requirements delineated in the ASTM E11-09 Standard Specification for Woven Wire Test Sieve Cloth (wire mesh). In this document, the nominal opening sizes and allowable variations are enumerated. In addition, three levels of appraisal and statistical confidence are defined for each nominal size. These levels or categories are defined as:
The number of openings that are measured and acceptable tolerances are specified for each category.
An extra charge for inspection and calibration category certification is normal. The charge usually ranges between $100 and $200.
Other standards organizations such as ISO and BSA use similar schemes.
As the mesh sizes get smaller, the proportion of openings measured becomes less. For example, the number of openings measured in a sieve with 1 millimeter openings equals approximately 0.06% of the total. Approximately 0.04% of the openings in a 300 micron sieve are measured. To get the confidence levels of each ASTM category, statistical formulas are applied to the actual measurements.
In addition, the specification prescribes the largest maximum individual opening in a test sieve. On a 1 millimeter sieve, this is 1.14 millimeters, or 12% larger than the nominal size. The relationship of largest maximum individual opening to nominal size on a 300 micron sieve is 18% larger, and 28% larger on a 75 micron sieve.
These certifications are frequently used as part of quality control management systems such as ISO 9000. However, there is a growing attitude that sieve calibration provides a more realistic standard than certification because the process measures the performance of a test sieve during a sieve test.
We understand that there is a need for continuity in quality management systems. Consequently, CSC continues to supply the Endecotts range of Calibrated Sieves. The frame and mesh sieves available can be found in the Endecotts Calibrated Department of our Online Store. Click on the button below to get to that part of the CSC store.