The term HEPA filter (from the English High Efficiency Particulate Air filter) indicates a particular high efficiency filtration system present in the most diverse sectors thanks to their many possibilities of use and applications.
HEPA filters are part of the category of so-called “absolute filters”, in particular they have a filtration efficiency between 85% and 99.995% and are classified according to their filtration efficiency in accordance with the UNI EN 1822 standards. They are in fact grouped into 5 classes with increasing performance characteristics.
The European standard for the classification of filters EN 1822-1:2009 refers to the classes:
- E10-E12 (EPA) high efficiency class also called “semi-absolute filters”;
- H13–H14 (HEPA) very high efficiency class also called “absolute filters”;
- U15–U17 (ULPA) very low penetration class.
The rating of the filter presents an index of least efficiency or maximum penetration, for a specific particle size. The certification of the class is based on the tests required by the EN 1822 standard and are indicated in the following tables:
| Class | Efficiency | Penetration |
|---|---|---|
| E10 | > 85% | ≤ 15 |
| E11 | > 95% | ≤ 5 |
| E12 | > 99,5% | ≤ 0,5 |
| H13 | > 99,95% | ≤ 0,05 |
| H14 | > 99,995% | ≤ 0,005 |
