This part of ISO 12103 specifies the particle size distribution of five inorganic test dusts used for the evaluation of filters. These dust are used in conjunction with various test procedures designed to evaluate, in general, fuel and lubricating oil filters for internal combustion engines by gravimetric methods. The dusts may also be used for a number of other applications, such as for abrasion tests, where distinct, known particle size distributions of hard, abrasive material are required.