ISO 14644 Part 3 guidelines


Upstream concentration is difficult sonetine when high volume flow if air there in HVAC system during filter integrity.
Is there any revision in guidelines . Earlier it was 10-100microgram/M3.
Why so big range is there . Is any chance error in case s person goes for 10 microgram or 100 micrograms.

So queries:

Is any guidelines are there .
Why so high range is given in guidelines

Dies it affect the accuracy of testing with variation in concentration
Is cold PAO is ok or Hot PAO
How to ensure leakfree arrangement in Plenum HEPA
Is it important to check prestage of HEPA ,in case second stage Terminal HEPA is there .

Kindly share and update