Recommendation for applying particulate integrity tests
When devices are equipped with particulate filters, either alone (1P configuration) or installed upstream of
activated carbon filters (1P1C, 1P2C configurations), particulate integrity tests are possible, in accordance with the
protocol described in Annex B of ISO 14644-3:2019.
This standard allows for testing using an aerosol photometer or a Light Scattering Airborne Particle Counter (LSAPC).
The amount of test aerosol released into the enclosure must be adjusted to the enclosure’s volume and airflow rate.
Special care must be taken to ensure homogeneous aerosol distribution within the enclosure volume.
The probability of HEPA filter integrity failure upstream of carbon filters due to improper installation is extremely low.
This is due to the ‘air break’ mounting principle, whereby any leakage is directed from clean air to contaminated air,
thus preventing contamination of the work environment.
Only mechanical damage to the filter surface may result in a risk.
Note: The aerosol photometer method offers ease of use but ‘may require a higher upstream aerosol concentration compared to the LSAPC method’.
The latter, according to ISO 14644-3:2019, ‘requires a series of calculations to be implemented and may also require a dilution system’.
For devices equipped with particulate filters located downstream of activated carbon filters (1C1P and
2C1P configurations), test aerosol challenge is not required.
These configurations are recommended exclusively for cleanroom installations.
In such cases, the efficiency of the particulate filters can be verified by a simple particle count downstream of the HEPA filter.
