Particle size affects the physical and chemical properties of materials and can be very important. The particle size may help determine strength — a food’s taste food may depend on its coarseness — and chemicals and other products may be sold by the range of granule size.

What Is a Sieve?

Sieves are mesh strainers, often made from brass or stainless steel. They are typically round, with solid metal walls connected to a woven metal screen.

They are often used with sieve receivers that collect the material that falls through the sieve. To prevent loss and contamination of the material, it can be protected by a sieve cover. Sieve covers are also necessary for covering the top sieve when multiple sieves are stacked on a laboratory shaker.

What Is Sieving?

Sieving is a technique for separating a sample into particles of different sizes. Sieving can be used to separate stones from sand, and is used in the food industry to help eliminate contamination by foreign bodies.

Analysis by sieving may require a single sieve or a set of mesh sieves, arranged by decreasing size of the mesh openings. Air flow, liquid, vibration, or another mechanical method is used to move the sample particles through the screens.

Critical variables include sample size, agitation parameters, duration, and end point determination. Sample properties, like hygroscopic or electrostatic tendencies, can present analytical challenges, and some samples may need to be suspended in a liquid for accurate measurement.

Types of Sieves

Sieves are available in different materials and mesh sizes. ASTM E-11 establishes criteria and tolerances for the openings in the woven wire mesh for standard sieve sizes. Some sieves are also traceable to NIST or must meet ISO 3310-1.

Sieve frames and meshes may be stainless steel or brass. Common diameters are 3, 8, and 12 in. and 200 and 300mm; non-standard sieves may have other diameters, including 6, 10, and 18 in. Heights range from 1 to 9 in. and may be designated as full, intermediate, or half-height. 

Mesh sizes are indicated in metric units or by the U.S. numbering system.