The EN 779 standard is based on the earlier Eurovent 4/5 and ASHRAE 52.76 standards, in which in situopacimetric dust spot efficiency and gravimetric retention are determined by well-proven methods.The CEN clasification is based on the old Eurovent specification,which divided filters into nine different classes.EU-1 to EU-9,on the basis of their average opacimetric and gravimetric efficiency.The EN 779 standard refers to filters by means of letters and numbers: | G-1,G-2,G-3 and G4 for coarse dust filters,F-5,F-6,F7,F8 and F9 for fine dust filters. |
Classification table according to the EN 779 standard filters | Filter Classification | Gravimetric Efficiency Am(%) | Dust Spot Efficiency Em(%) | | G-1 | Am<65 |
| | G-2 | 65<=Am<80 |
| | G-3 | 80<=Am<90 |
| | G-4 | 90<=Am |
| | F-5 |
| 40<=Em<60 | | F-6 |
| 60<=Em<80 | | F-7 |
| 80<=Em<90 | | F-8 |
| 90<=Em<95 | | F-9 |
| 95<=Em |
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