ISO 16890 for air filters: facts for professionals
Whoever is professionally involved with air filtration must be familiar with the new ISO 16890. Now reading standards is not one of most people’s favourite pastimes. So we have summarized all essential aspects of the new filter check and classification for you. One very detailed and detailed and one short summary for all who only want to know the essential:
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The new DIN EN ISO 16890
The air filter
Air filters for ventilation applications are manufactured from a wide variety of filter materials. These materials, which are used in different ways, achieve their separation efficiency in comparison to the substances and particle sizes to be filtered through very different functional principles.
Air filters do not function exclusively as a mesh that retains all particles with a larger diameter due to its mesh size. Fine dusts with smaller diameters are separated from the flowing air in the filter material by various physical and chemical processes. In addition to mass inertia, electrostatic charges and other adhesive forces play an important role here, especially in synthetic filter materials.
Since the mix between these separation forms is different for each filter material, the performance of filters varies greatly due to environmental influences and other factors.
In general, the filter effect increases with the operating time and the loading condition, as the “meshes” are increasingly reduced by the absorbed particles.
As of July a new standard for air filters applies: DIN ISO 16890
At the turn of 2016/2017, a new filter standard, DIN EN ISO 16890, was introduced unnoticed by many. It finally replaces EN 779 at the end of an 18-month transition period on 01.07.2018. With far-reaching consequences.
From July 2018, filters may no longer be traded and installed with the previously known classification G1 to F9. From this point on, only filters that have been tested in accordance with DIN EN ISO 16890, divided into corresponding groups and sufficiently marked are to be used.
Air pollution by fine dust is increasing worldwide. Due to the proven negative impact on human health, this problem is increasingly moving into the public focus. According to the latest findings, high levels of particulate matter are the cause of many respiratory and cardiovascular diseases. Especially in particle sizes smaller than 10µm, the mixtures of solid and liquid components, known as fine dust, are not only respirable, but sometimes even enter the human bloodstream via the lungs.
The health risks of excessive exposure of breathing air to fine dust are consequently classified as considerable by many countries. In order to take cross-border measures against this development, uniform standards and measurement procedures have been established in recent years, which enable an accurate assessment of fine dust pollution.
Fine dusts are now divided into different particle size fractions. More and more organisations and authorities worldwide determine and publish fine dust values in the PM10, PM 2.5 and PM1 fraction groups, thus making it possible to compare your measurement or limit values. The PM 10 group comprises all fine dusts with particle sizes up to 10µm, PM 2.5 to 2.5µm and PM1 to 1µm.
DIE DIN EN ISO 16890
DIN EN ISO 16890 takes up this approach and no longer distinguishes filters from a single particle size of 0.4 µm according to their separation behaviour, but divides filters into 4 new groups.
– ISO Coarse filter for dust from 10µm
– ISO ePM10 0.3µm to 10µm
– ISO ePM2.5 0.3µm to 2.5µm
– ISO ePM1 0.3µm to 1µm
Measurement and evaluation methods according to ISO
The measurement and evaluation procedure for the filter groups ISO ePM10 to 1 is considerably more complicated than according to EN 779 due to the new approach.
The test for classification into ISO groups can no longer be evaluated gravimetrically, i.e. by simply weighing a filter before and after exposure to test dust, since ISO requires a statement to be made about the actual separation behaviour of a filter with respect to each particle size.
It is therefore necessary to measure the actual number of separated particles per particle size and to compare it with the particle quantities added during the experiment.
In order to test the separation behaviour of the filters even under unfavourable operating conditions, ISO 16890, like EN 779, specifies test cycles with untreated and electrostatically discharged filters in order to evaluate the test filter even in the most unfavourable operating conditions.
The aim of the measurement is to determine the initial fractional separation curve, i.e. the depiction of the separation efficiency in relation to the particle size for the unloaded and unconditioned filter, and the minimum fractional separation efficiency curve of the electrostatically discharged filter.
The curve of the average fractional separation efficiency is then determined from both curves. During the measurement, values such as the initial pressure difference, the nominal volume flow and the dust holding capacity are also checked.
Each test is carried out according to a fixed procedure and defined test method.
Filters that are not grouped into one of the three ISO ePM groups are a special case, as they do not meet the minimum requirements of the ePM10 group. These filters are usually comparable to the old classes G1 to G4 and, in analogy to the old test procedure according to EN 779, are subjected directly to a synthetic dust mixture until the final pressure difference is reached. The filtration efficiency and dust holding capacity for these filters are then determined gravimetrically.
Rating all filters
In order to achieve the most realistic assessment of the filters possible, ISO 16890 does not directly convert the fractional efficiencies determined in the measurement process into the fine dust efficiencies ePMx required for the filter grouping, but takes into consideration the average distribution of the particle size in the ambient air.
Two standardized distribution curves were developed for this purpose, from which average particle counts in % in the individual particle sizes can be derived for an urban and a rural environment.
Using the mathematical functions of these distribution curves, the measurement results of the fraction distribution curves are weighted differently. If, for example, a filter has poor separation behaviour with respect to a particle size y and this particle size only occurs in small percentages according to the distribution curve in the urban or rural ambient air under consideration, the corresponding average fractional separation efficiency of the particle size is only included in the final result with a correspondingly small proportion, i.e. the fine dust separation efficiency ePMx.
The calculations of the average fine dust collection efficiencies ePM10 to ePM1 and minimum fine dust collection efficiencies ePM 2.5 min and ePM 1 min are carried out according to predefined formulas from the previously calculated average and minimum fractional separation efficiencies and the standardised particle size distribution. For ePM1 and ePM2.5, urban particle distribution for ePM10 is the rural one.
The Group Assignment
The filters are assigned to the correct ISO group by comparing the calculated ePM10 or ePM 2.5 min and ePM1 min values with the threshold values of the standard. A filter qualifies for a group if the calculated ePM or ePMmin value is greater than or equal to the 50% threshold value. Each filter is only assigned to the highest group for which it meets the requirement criteria.
– A filter achieves an ePM10 value of 80%, an ePM2.5 min value of 75% and an ePM1 min value of 55%.
This filter meets all minimum requirements and is therefore classified in the ISO ePM1 group.
– A second filter achieves an ePM10 value of 60%, an ePM2.5 min value of 48% and an ePM1 min value of 25%.
This filter only meets the requirements of the ePM10 group and is therefore grouped there.
If a filter does not reach the 50% threshold with its ePM10 value, this filter must be grouped in the ISO COARSE group.
The classification values of the filters are formed from the calculated average fine dust collection efficiencies ePM by rounding this value off to the next multiple of 5%.
Example: A filter has a calculated value of ePM2.5 78%, the classification in this case is 75%.
All filters for ventilation systems affected by ISO 16890 must be marked ISO-compliant and clearly visible after the end of the transition period.
The label consists of the ISO grouping and the classification of the filter.
– ISO COARSE 90% This filter does not reach any of the ePM groupings and has a gravimetric separation efficiency compared to synthetic test dust L2 (ISO 15957) of 90%.
– ISO ePM2.5 65% This filter achieves a minimum efficiency of 50% compared to dusts with particle sizes of 0.3µm to 2.5µm and has an average efficiency of 65% for this particle size range.
– ISO ePM1 80% This filter achieves a minimum efficiency of 50% compared to dusts with particle sizes of 0.3µm to 1µm and has an average efficiency of 80% for this particle size range.
In general, filters may only be marked with a grouping and the corresponding classification. However, the achieved mean separation values for the other ISO classes can be additionally stated in technical documents and all accompanying documents.
The advantages of ISO 16890
The advantages of the new ISO classification are obvious. By specifying the average separation rates in a recognised gradation, it is possible for the first time to calculate and prove the achieved air quality of an air conditioning system for the planned site in advance.
The fine dust load values for outside air available nationwide can be calculated quite simply with the separation capacity of the filter or the filter stage. This directly results in the expected particle load for the planned ventilation system.
Disadvantages of ISO 16890
The old classes of EN 779 are not compatible with the new groupings and classifications of ISO 16890, since different measurement and assessment procedures are given for the certification of filters.
The conversion of a filter used so far to a new product can therefore not be listed universally in translation tables. Standard filters from Felderer have been converted by us and partly converted to new filter media, so that the following comparison table between EN 779 and ISO 16890 can be provided for these filters.
|<Old EN 779||<<ISO 16890|
|G4||<ISO COARSE 90%|
|M5||<ISO ePM10 70%|
|M6||<ISO ePM2.5 55%|
|F7||<ISO ePM2.5 65%|
|F8||<ISO ePM1 75%|
|F9||<ISO ePM1 80%|
This table allows a simple conversion of previously related HTH filters between EN 779 and ISO 16890 If other standards or guidelines, such as the current version of VDI 6022 and other future standards, are relevant for the use of an ISO filter in your plant, the conversion cannot be based solely on this table.
The change of the filter evaluation by ISO 16890 results in a high need to change other standards, regulations and guidelines which still refer to the old EN 779-2012 and the classification system laid down therein. Until these standards are revised, difficulties in interpreting individual regulations cannot be ruled out.
The new version of VDI 6022 (2018) is the first guideline to take up the new classifications and stipulate minimum collection efficiencies. This new version results in a considerable need for refurbishment of existing plants, as a conversion of these plants to ISO-certified filters is specified for the scope of the directive.