Standard EN 1822:2010

The most widely accepted international standard for filter classification of HEPA and ULPA filters is EN 1822, used by the European Standardization Institute.

Standardized testing shows minimum initial efficiencies for each filter class, computed "leak-free". A special DEHS test aerosol is used for the test. The particle number on the filter inlet side is measured by a high-level particle counter; a scanner scans the entire filter surface and the probes suck a defined amount of air through the filter, while scattered-light particle counters count the particles passing through. In this way, local penetration and local filtration can be shown. The standard indicates the permissible degree of penetration for each filter class, and the integral (overall) penetration value is calculated as the arithmetic mean of the local values.

The five parts of EN 1822:2010

• Part 1: Classification, performance testing, marking.
• Part 2: Aerosol production, measuring equipment, particle counting statistics.
• Part 3: Testing flat sheet filter media.
• Part 4: Determining leakage of filter elements (scan method).
• Part 5: Determining the efficiency of filter elements.

Classification of EPA, HEPA and ULPA filters

Filter class	Integral value efficiency (%)	Penetration (%)
E10	≥ 85	≤ 15
E11	≥ 95	≤ 5
E12	≥ 99.5	≤ 0.5
E13	≥ 99.95	≤ 0.05
E14	≥ 99.995	≤ 0.005
E15	≥ 99.9995	≤ 0.0005
E16	≥ 99.99995	≤ 0.00005
E17	≥ 99.999995	≤ 0.000005

> Technical review flag: the source table listed "E10" twice; the second row (≥ 95% / ≤ 5%) is presumed to be E11, as in the published standard. This correction is flagged for technical review rather than silently changed elsewhere. Decimal commas from the source were normalized to decimal points.