- for the purpose of Test Method D4749, the sieve designating the lower limit or bottomsize shall be that sieve of the series given in the Standard Series of Sieves section with the largest openings through which passes a total of less than 15 % of the sample. This defined bottomsize is not to be confused with the size of the smallest particles in the lot.DISCUSSION — (Warning — In the case of a commercial, doublescreened product, for example, 37.5 by 9.5 mm (11⁄2 by3⁄8 in.), this designation may not be valid. In such commercial or contractual situations, the amount of allowable material smaller than the bottomsize (for example, 9.5 mm) must be specified by the contract under which the coal is bought and solid.) D4749
ASTM D121-09a Standard Terminology of Coal and Coke. 2014.