DIN EN ISO 16890 determines filter performance according to fine dust fractions

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The standard DIN EN ISO 16890 "Air filters for general ventilation", which has been valid worldwide since July 2018, marks a new development stage in the standardized process for testing and classifying filter classes G, M and F. The new process provides significantly more reliable data on the actual filter performance and thus enables optimum filter selection specifically according to the requirements.

To date, the separation efficiency of filters has been determined in accordance with DIN EN 779. Accordingly, the efficiency of particle air filters was tested with a synthetic test dust (ASHRAE dust) having a uniform particle size of 0.4 μm. However, since fine dust is not homogeneous in size and shape, the test values of the "laboratory test" have only limited significance for everyday operation.

On the basis of the fine dust classes for evaluating outdoor air pollution – issued by the World Health Organization (WHO) and environmental authorities – the now valid DIN EN ISO 16890 allows a practical assessment of filter effectiveness.

For this purpose, the suitability of a filter for filtering or reducing different particle sizes from 0.3 µm to 10 µm is measured. Depending on its efficiency, the filter is assigned to filter classes PM10, PM2.5 and PM1.

The new test procedure leads to a more differentiated assessment of the actual efficiency of air filters. The ISO standard divides coarse and fine dust filters into four groups depending on their separation efficiency. The decisive factor here is whether a filter can separate more than 50 percent of the corresponding particle size range (see Table 1: Filter groups according to ISO 16890).

Determination of the separation efficiency according to ISO 16890

The electrostatic charge of synthetic filters generates an attraction effect that attracts particles and improves separation efficiency. The electric charge decreases steadily during operation and the effect declines accordingly.

Laboratory tests of a statically charged filter therefore say very little about its performance in everyday operation. The new test procedure according to DIN ISO 16890 takes this circumstance into account. The filter elements are therefore measured both in the charged and discharged state.

In the first test step, the profile of the pressure difference can be recorded as a function of the volumetric flow. The fractional separation efficiency is then measured for particles with a size of 0.3 µm - 10 µm. In order to test the air filters as realistically as possible, the filter is electrostatically discharged before the separation efficiency and the pressure difference are measured again.

The average filtration efficiency for the fine dust fractions PM1, PM2.5 and PM10 is derived from the results of the tests.

Local air quality decisive for system planning

The corresponding filter classes for air handling units (AHU) are determined taking into account the fresh air quality (ODA/AUL) as a function of the required supply air quality (SUP/ZUL). If the specifications for fresh air and supply air quality are combined with the respective air filter qualities to be used, the assignment shown in Table 2 results according to VDI 6022 sheet 1 "Hygiene requirements for ventilation and air-conditioning systems and units" (Table 2: Required filter quality depending on the existing fresh air quality and the desired supply air quality according to VDI 6022 sheet 1 (01/2018)).

Table 1: Filter groups according to ISO 16890

Filter class

Efficiency range

Examples for fine dust

ISO ePM1

ePM1, min  ≥ 50%

Ultrafine dust with a diameter of less than 1 µm:

Viruses, bacteria, nanoparticles, soot (from fossil fuels)

ISO ePM2,5

ePM2,5, min ≥ 50%

Fine dust with a diameter of less than 2.5 µm: bacteria, fungal and mould spores, pollen, toner dust

ISO ePM10

ePM10   ≥ 50%

Fine dust with a diameter of less than 10 µm: pollen, rock dust, dusts from field cultivation

ISO coarse

ePM10   < 50%

Visible coarse dust: sand, hairs and leaves, lint, airborne seedlings, etc.

Table 2: Required filter quality depending on the existing fresh air quality and the desired supply air quality according to VDI 6022 sheet 1 (01/2018)

 

SUP/ZUL 1

SUP/ZUL 2

SUP/ZUL 3

ODA/AUL 1

ePM10 50% +

ePM1 50 %

ePM1 50 %

ePM1 50 %

ODA/AUL 2

ePM2,5 65% +

ePM1 50 %

ePM10 50% +

ePM1 50 %

ePM10 50% +

ePM1 50 %

ODA/AUL 2

ePM1 50% +

ePM1 80 %

ePM2,5 65% +

ePM1 50 %

ePM10 50% +

ePM1 50 %

Info box

Which old filter classes correspond to the new filter classes?

Orientation aid of the Professional Association of Air Conditioning in Buildings (Fachverband Gebäude-Klima, FGK) and the European Ventilation Industry Association (EVIA):

Filter class according to EN 779

Filter class according to EN 16890

G2

ISO coarse ≥ 30%

G3

ISO coarse ≥ 45%

G 4

ISO coarse > 60%

M5

ePM10 ≥ 50%

M6

ePM2,5 ≥ 50%

F 7

ePM1 ≥ 50%

F 8

ePM1 ≥ 70%

F 9

ePM1 ≥ 80%


At least one ISO filter ePM1 ≥ 50% must be used in the last filter stage. 

Author
Tobias Brugger
 
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