Suggest about importance of pressure drop of HEPA filters of aseptic area in HVAC validation.
And procedure to find out same and criteria.
PD for each HEPA filter has a proportional relation versus air velocity,
PD is the resistance of HEPA filter to the air flow during air passing across the filter,
Each manufacturer tries to minimize PD to save electric cost,
The important factor in the process is the amount of air pass through the filter which determined by air velocity, "should be from 0.36 to 0.54 m\sec,
However, HEPA filter should be changed when, (it can’t achieve the amount of air, it duplicates it’s initial pressure, & no longer permits the air passing = clogged)
PD tested by manufacturer to prove its efficacy = 99.995% then list the tested PD on the name plate of filter (certified)
HEPA filter should be tested circularly by POD test to check any leakage,
This for HEPA filter of booth down flow unit
I think it will be same in some points in HAVAC
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