Pre-Filters and Particulate Filters
In Europe, Standard EN 779 is exclusively used to classify coarse and fine dust filters (= particulate matter filters). In the United States this is referred to as the American ASHRAE 52.2 standard. EPA, HEPA and ULPA filters, particularly fine-pored particulate matter filters, are rated in accordance with standard EN 1822. Depending on the standard, either the initial separation efficiency or the fractional separation efficiency is used as the performance criterion for standard contamination.
The following table shows the usual standards and the classifications used in Europe (standard EN 779) to specify the correct filter to match the particulate size.