Test sieves are woven wire or perforated metal pans that are used for sifting and filtration. Test sieves are accurately constructed by placing wire cloth between two suppressed die formed frames. Stainless steel or brass is generally used in the construction of both the frame and woven wire mesh that performs the straining. These devices are very accurate, and are widely used in all types of laboratory particle analysis.
Test sieves are available in a variety of standard diameters (3, 5, 6, 8, 10, 12, and 18 inches, and 200, 300, or 400 mm). Specialized or proprietary sizes, either larger or smaller, are also available, although far less common. Test sieves are also available in a variety of heights, either full height (typically full height is 2 5/8"), half height (typically 1 5/8”), or a variety of intermediate sizes between.
Test sieves are engineered to the rigorous standards of the International Organization for Standardization (ISO), Standard 3310-1, or to the U.S. Standard as per ASTM E-11. Additionally, precision electroformed sieves are standardized to ASTM E161, while perforated plate sieves are manufactured to ASTM E323, or the British Standard BS140-1, as well as ANSI 2000. All of these Standards detail a number of specifications to which any rated test sieve will adhere. These ratings include permissible opening sizes, opening dimensions, maximum number of allowable openings in each test sieve, and nominal wire diameter.
Test sieves are available in a number of specific configurations. These include certified, matched, calibrated, matched and calibrated, and midpoint. Certified are the most widely used test sieves and are manufactured to a National or International Specification. Each is supplied with a Certificate of Conformity and individually numbered to provide full traceability. Matched style is comprised of two or more test sieves each fitted with a sieving medium having similar aperture characteristics. Each is supplied with a Certificate of Conformity. Calibrated sieves are calibrated in accordance with the specification. Each sieve is supplied with a calibration test certificate giving the range of tolerances and measurements taken. Midpoint test sieves are fashioned from a more precise sieving medium where specification tolerances are reduced by 30% where attainable. Each sieve is supplied with a test certificate giving the range of tolerances and measurements taken.
Some test sieves are supplied with top covers and/or bottom pans. Top covers serve to contain the media dust or filtered matter within the sieve when under vibration and also keep the sieve clean when not in use. Bottom pans collect the sieve media or filtered matter for future use.