Checking HEPA filters?
MCSpear at msn.com
Sun Nov 3 04:35:00 EST 1996
Have you tried "scanning" the filter face with an open petri dish?
This won't reveal small problems but will give you a general idea.
Another crude method is to buy, borrow, rent or make a hot wire
anemometer (less than $250) and scan the filter face. Look for spots
where the air is moving faster than the surrounding. These could be
holes or split seams. Also see if there is sufficent air velocity.
If you can't get 70-80 fpm the filter may already be plugged.
Concerning holes and splits. In many cases these are repairable with calk.
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