AC Coarse Test Dust (ACCTD) / AC Fine Test Dust (ACFTD)

AC Coarse Test Dust (ACCTD) and AC Fine Test Dust (ACFTD) are standardized test dusts developed to evaluate the performance and durability of filters and filter media under controlled conditions. They are based on the categories described in ISO 12103-1 and were originally formulated by manufacturers in Arizona to simulate the range of fine and coarse dust particles found in real-world industrial and automotive environments.

AC Fine Test Dust consists of finely ground quartz and mineral particles with a controlled particle size distribution, typically ranging from submicron particles up to about 80 µm, with a median diameter of approximately 20 µm. AC Coarse Test Dust contains a higher proportion of larger particles, up to around 200 µm, with a median of about 80 µm. Both dusts are carefully blended and sieved to ensure consistent properties from batch to batch, allowing for comparable results across different laboratories.

In filtration tests, the dust is introduced as an aerosol into an air or liquid stream and passed through the filter under evaluation. Parameters such as pressure drop, dust holding capacity, and filtration efficiency are used to assess how quickly a filter clogs, how effectively it retains particles, and how much contaminant it can hold before cleaning or replacement is required. While the exact composition is proprietary, performance characteristics and particle size distributions are documented in ISO and SAE standards.

At GKD, ACCTD and ACFTD are used to investigate the dust holding capacity and efficiency of metal and polymer process belts. Their defined composition enables the simulation of real operating conditions—from heavy industrial dust to fine atmospheric particles—and ensures reproducibility in the development of new filter media and spiral weaves.

The test dusts are derived from natural road sediments through crushing, grinding, sieving, and thermal treatment to remove organic contaminants. They are then washed and classified into defined fractions. Some applications mix the dust with oil or water to simulate aerosols or emulsions. During testing, standards define the flow rate, dust concentration, and duration. The filter’s behavior under these reproducible conditions provides data for selecting wire diameters, weave types, and material combinations. As such, ACCTD and ACFTD are indispensable tools for product development, certification, and quality control in the filtration industry.