The Basic Element of Sieve Testing
A sieve is a device used to separate solids based on size. Sieves have been in use since ancient times- the first recorded usage was in Egypt, over 5,000 years ago.
Sieves are used for a variety of applications, including Sieves are widely used to evaluate the uniformity of granular material, as well as measure particle size in powder form. Sieves are used in research and development, environmental monitoring, and quality control. Specific applications include sieving soil samples in the construction industry, separating particles in chemical and pharmaceutical processes and measuring the particle size distribution in food production.
Our range of sieves are in the category of laboratory and quality control test sieves.
Sieves are constructed of a frame, mesh material, and clamping device. The frames can be made of brass, Stainless Steel or acrylic. Standard frames are round and come in diameters of 3 inch, 8 inch, 12 inch diameters (also available in metric equivalents). Options of full height and 1/2 height and are available as deep water wash sieves.
The mesh material can consist of woven wire mesh, perforated plate or electroformed material.
The sieving process involves passing a material through a mesh or other device with an opening size of less than the material’s particle size. The particles will either pass through to the other side, be caught in the mesh, or be deflected according to the shape of the opening.
The process can be done manually, but is usually affected by a mechanized sieve shaker. See our range of sieve shakers here.
Our selection includes frame diameters from 100mm / 4 inches to 450mm / 18 inches in stainless steel and brass frames.
Sieve mesh material options include stainless steel wire mesh in aperture sizes from 125 millimeters (5 inches) to 20 microns, electroformed openings as small as 2 microns, and perforated plate of various shaped holes.
ASTM and ISO have set standards for mesh designations, inspection criteria and acceptable tolerances.These are defined for ASTM in a the table USA Standard Sieve Specification.
.You may notice that the acceptable variation in mesh hole size becomes a larger portion to the nominal size as the holes become smaller. Because of these wide variations the certification of as sieve should be viewed as only an insurance policy - assurance that a sieve's mesh is within a required specification. It is not a valuable predictor of a sieve's performance.
The acceptable variations in the apertures of wire mesh sieves is stated in the basic ASTM Document. Three level of validation have been established.
Sieve Calibration using calibrated spheres relate to a sieves performance.
The development of microspheres with tolerances as tight as +/- 0.5 microns in diameter has made possible a new way of thinking about sieve certification and calibration.
Rather than simply an assurance that a sieve conforms to the construction and tolerance parameters set by stands organization such as ASTM and ISO, calibration using micro spheres provides a measure of operational performance.
To calibrate a sieve,the complete contents of a single dose bottle of microspheres of a specified size is poured onto the sieve surface and shaken for about 1 minute. As standards are spherical they have a very high sieving rate that is independent of the shaking method. Therefore manual shaking, mechanical or electromechanical action, Airjet and sonic sieving all give the same results.
The percentage of the microspheres passing is then used to determine the aperture size from the calibration graph on the Certificate of Analysis. Because the size distributions are so narrow. Variations as 5% in the percentage passing. For example with a 63 micron sieve, the mean aperture difference is about 1 micron, making the technique highly accurate.
Watch this Video - How to run a Sieve calibration.
The introduction of narrow particle size distribution standards has at last brought sieve calibration directly into the laboratories using the sieves and answers the demand for routine inspection by regulatory bodies. This novel approach to sieve calibration fulfils all of the requirements of the quality control laboratory by delivering simplicity, speed, accuracy and above all, NIST traceability to the International unit of length.