What is EN779 ?

General
The procedures described in this standard have been developed from those given in EN 779:2002. The basic
design of test rig given in EN 779:2002 is retained. A challenge aerosol of DEHS (or equivalent) is dispersed evenly
across the duct upstream of the filter being tested. Representative upstream and downstream air samples are
analysed by an optical particle counter (OPC) to provide filter particle size efficiency data.
Classification
The EN 779:2002 classification system (comprising groups F and G filters) has been changed to three groups (F-,
M- and G-filters).  

Filters found to have an average efficiency value of less then 40 % of 0,4 µm particles will be allocated to group G
and the efficiency reported as “< 40 %”. The classification of G filters (G1 - G4) is based on their average
arrestance with the loading dust.  

Filters found to have an average efficiency value from 40 % to less than 80 % of 0,4 µm particles will be allocated
to group M (M5, M6) and the classification is based on their average efficiency (0,4 µm). The filter classes F5 and
F6 have changed to M5 and M6, but with same requirements, as in the old classification system.

Filters found to have an average efficiency of 80 % or more of 0,4 µm particles will be allocated to group F (F7-F9)
and the classification is based on their average efficiency (0,4 µm) as in the old system and the minimum efficiency
during the test.