Laminar Air Flow/ HEPA filter Alarming

[bocearnaigh]

A query re. Laminar air flow hoods/ Ceiling mounted HEPA banks.
I am considering alarming low air flow using Dwyer Photohelics which will pick up on DP across HEPA’s.
However, if there is minor damage to filter (imagine a pin hole) the DP (related to airflow) will possibly remain within limits but the filter will probably fail on next DOP test.
How do I best protect myself against low airflow & filter damage in a sterile manufacturing area in a pharma plant?
Thanks,
Brendan

 

[ChasBean1]

It wouldn't be done practically by monitoring DP or increasing periodicity of DOP testing. Proactive particle monitoring in the space would probably be the best way. See if you can research USP 797. They recommend particle monitoring at no more than 6 month intervals. If it's critical, I believe there are systems that can continuously monitor particulate the space and log data.

Try these guys for starters:

http://www.metone.com/particulate.htm

CB

 

[asaxplayer]

I think a pressure switch might be better, which can be connected to a LED on the surface of the unit to show that the filter needs to be replaced. (Instead of maintenance having to read the gage, figuring out whether the reading is critical, a RED LED would probably be easier to figure out:"something's wrong".)
As for filter damage, after DOP testing, carefully use a perf. plate or some sort of grill to cover the face. There shouldn't be any reason that the filter will be damaged after you have properly installed it into the ceiling. (and scheduled checks)

 

[quark]

Finding defects of a HEPA filter using a DP device is too ambitious, IMHO. I didn't see any fiter getting damaged, during the course of their usage, on its own. The dp gauge gives you (only)indication of the end of filter life beyond its maximum allowed pressure drop.

Just believe in periodical DOP and periodical (or continuous) particulate measurement. Retrospective data will save you from the regulators.

Good luck,