The European standard EN 779:2012 entitled “Particulate air filters for general ventilation” constitutes the relevant legislation for test and classification of filters used in general ventilation and way of test for measurement of performance of filter. This European standard refers to the filters for air purification which starting efficiency is lesser than 98% evaluate on polluting particles of 0.4 µm (micron).

The methodology described in the standard is based on a laboratory test procedure, with the aim of achieving reproducible and comparable results.

Filters are tested with a test volume flow between 0.24 m3/s (850 m³/h) and 1,5 m³/s (5400m³/h): since a filter’s operational behaviour depends on the volume flow in operation, the filter classes and all other test results from the test performed in accordance with EN 779:2012 always relate only to the test volume flow specified in each case. The principal results of the test are:

  • Gravimetric arrestance efficiency;
  • Efficiency on 0.4 µm particles;
  • Pressure drops;
  • Dust holding capacity.

The most significant change connected to this European standard – that was adopted in Italy in June of 2012 – is about the introduction of minimum efficiency for Fine filters (F7, F8 and F9) and the renaming of Fine filter classes F5 and F6 as “Medium”, that is M5 and M6.

The introduction of these minimum efficiencies represents a milestone in the filter industry as it raises the quality standards, improving the care of human health.

The European standard EN 1822:2012 is the reference standard on air filters with high and very high efficiency filters and with ultra-low penetration (EPA, HEPA and ULPA): this norm establishes a procedure for the determination of efficiency of filters using a method for the quantitative estimate of pollutant particles remaining after treatment with liquid aerosol. In this way it’s possible to obtain the classification of filters in a normalized way, facilitating the European commercial exchanges.

The methodology described in the standard EN 1822 permits to:

  • Asses the efficiency of filters, counting particles hold by the filter and size for which the efficiency of the filter is minimal. This size is known as Most Penetrating Particle Size (MPPS);
  • Check for the leaks of filter, local and total.

Compared to the previous standard published in 1998, efficiency classes H10, H11 and H12 have been renamed as E10, E11 and E12.

Following the enactment of this norm absolute filters are classified as follows:

  • EPA 10 – EPA 12 : Efficiency Particulate Air Filters
  • HEPA 13 – HEPA 14 : High Efficiency Particulate Air Filters
  • ULPA 15 – ULPA 17 : Ultra Low Penetration Air Filters

The technical national standard UNI 11254:2007 titled “Active electrostatic air filters for general ventilation – Definition on filtration efficiency” refers to the air filters intended for general ventilation, functioning through one or more electrostatic fields actively applied by means of a generator.

The content of this norm concerns:

  • Classification of filter following the evaluation of average efficiency on particles of 0,4 µm in diameter;
  • Complete description of test circuit, test method and procedures for qualification.