≥5 micron macroparticles measurement in Laminar Airflow (LAF) bench (ISO Class 5)

#1
Hi,
We’ve used to measure 0.5 and 5.0 micron of particles in Laminar Airflow (LAF) bench (ISO Class 5). After revision of ISO 14644-1 standard (ISO 14644-1:2015), we started to measure 0.5 and 1.0 micron particles, because ≥5 micron particles were defined as macroparticles in case of ISO 5 class. But there are many companies that require measuring of 5.0 micron particles due to the GMP guidelines. This makes routine tests more difficult due to the increased sampling time (20 minutes instead of 1 minute).

As I know, there are two options in this case:
(A) Measuring of 5.0 micron particles for 20 minutes
(B) Sequential sampling per Annex D for decreasing the sample time. I have a problem with sequential sampling. I’m not sure I can use this method for measuring 5.0 micron particles in case of ISO 5 class, because there is no b mark on this place in Table 1 (ISO 14644-1:2015), which refers to sequential sampling method.

Could you share your experiencies about this? How could you handle this problem?

Thanks for all your answers!
 

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