ISO 16890 is the international classification system for particulate air filters used in general ventilation. It is commonly applied to panel, bag, pocket, V-bank and other filters installed in HVAC and air-handling systems.
The standard reports filters as ISO ePM1, ISO ePM2.5, ISO ePM10 or ISO Coarse. These groups provide a common basis for comparing laboratory performance across a range of particle sizes.
The laboratory first measures fractional efficiency at defined particle-size intervals. The resulting efficiency curve is combined with standardized reference particle-size distributions to calculate the ePM values. The classification considers both initial performance and the minimum fractional test efficiency determined after the specified conditioning procedure.
An ISO ePM2.5 65 percent result is therefore a standardized calculated classification. It does not mean that the filter will remove exactly 65 percent of every real outdoor PM2.5 aerosol in every building. Field performance also depends on local particle distribution, airflow, loading, installation sealing and maintenance.
| Function | Purpose | Important boundary |
| Fractional efficiency and resistance | Measures upstream and downstream particle concentrations and airflow resistance. | The result is an efficiency curve, not one value at 0.3 micrometres. |
| IPA-vapour conditioning | Determines minimum fractional test efficiency after reducing removable electrostatic effects. | It is not a simulation of a fixed period of field ageing. |
| ePM classification | Uses the initial and conditioned data with the standard reference distributions. | The value is a laboratory classification, not a direct field-removal guarantee. |
| Dust loading | Measures gravimetric efficiency and resistance against captured test-dust mass. | ISO 16890-3 data are reported separately and do not determine the ePM class. |
A complete ISO 16890 laboratory may require an airflow test duct, aerosol generators, particle measurement instruments, pressure and flow measurement, an IPA conditioning cabinet, dust-feeding and weighing equipment and software for test control and calculations. These functions may be provided by separate modules rather than one physical machine.
SCPUR configures ISO 16890 test systems according to filter size, airflow range, pressure drop, required test parts, daily throughput and reporting needs.
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