| Because you'll be living with your replacement
filters for the next year or so, you'll want to make sure the ones you pick are right for
your job. Here are some things you should look for: ASHRAE
efficiency: Your assurance that a precise industry-wide testing standard is
used to determine the dust-removing capability of the filter. If a manufacturer
certifies the ASHRAE efficiency of a filter (or better still, if he will offer the
certified test data of a qualified independent test laboratory), you should have
confidence that the filters will perform as stated.
Confirmation of claimed initial resistance: You'll want to make sure
the initial resistance of the filters will be as stated in the manufacturer's
literature. Again, the manufacturer might be able to offer certified test data of a
qualified independent test laboratory, or if you wish, you can arrange for initial
resistance tests by someone you select.
Filter life "guarantees": Carefully consider all of
the conditions which accompany any "blanket guarantee" of filter life.
Usually they are accompanied by a stipulation that operating conditions must not change (a
condition you may not always be able to control), or other limiting measures.
Confirmation of amount of media: Ask the manufacturer for a
sample of the filter you are considering, and measure its media area. Remember,
though, that two filters having the same amount of media will only have the same life if
they also have the same initial resistance. Filters with a higher initial
resistance to air flow start with a handicap they can never overcome.
Keep in mind, too, you're not necessarily "boxed in" with the filters you've
been using. Most filter frames will accept cartridges of other manufacturers, if you
decide a change is worthwhile. You'll want to use the filters that do the best job
for you. They probably won't be the least expensive filters you can buy. But
they could save you money over the long haul. |
