Home' Facility Perspectives : Vol 9 No 3 Contents SPONSORED ARTICLE
26 FACILITY PERSPECTIVES | VOLUME 9 NUMBER 3
Selecting the right filter for your facility's needs
Air filters are a critical component in maintaining the air
quality and energy efficiency of your site. This guide will
help you to select the right filter for your facility's needs.
Filter size and ratings
Nominal filter dimensions can vary by manufacturer, so when
dealing with replacement filters, it is essential to know the actual
filter dimensions and the quantity required before you reorder.
Accepted filter performance rating systems are EN779:2012
(G1 to F9) and ASHRAE 52.2 (MERV 1 to 16). Based on the
successful removal of airborne particles by size, these ratings
provide a relative measure of filter effectiveness, whereby
lower-rated filters remove larger-sized particles, and higher-
rated filters remove smaller-sized particles.
Higher-rated filters will remove more airborne particles;
however, this is almost always at the cost of energy and more
frequent filter changes. Similarly, lower-rated filters will impact
air quality, duct cleanliness, heat exchanger performance
and, in some cases, safety.
Inspection of your current filters will reveal their rating, and
you should replace these filters with a comparable rated filter.
With large installations, it is worth checking the original filter
specifications to confirm that the right filters are still installed.
While nominal dust-holding capacities obtained from controlled
laboratory testing are useful when comparing similar filters
within a manufacturer's range, comparisons between different
filters or manufacturers can be misleading due to differences in
test conditions, dust ranges and other factors.
Similarly, real-world dust, temperature, humidity and other
contaminations are difficult to directly relate to this laboratory
test data. As such, you should seek advice from suppliers with
reputable technical knowledge and experience. Ultimately, with
replacement filters, actual historic data will be your best guide.
Finally, all filters have a finite capacity and benefit from
a 'staged' sequence -- for instance, pre-filters, followed
by higher-efficiency final filters. Filter sequencing allows
inexpensive filters to be sacrificed, in order to maximise the
life of the more valuable final filter.
Static pressure is the recognised measurement to
assure appropriate filter change-out times. For example, if the
static pressure across a G4 filter was measured above
175 pascals, it is demanding to be changed. While this filter
is still providing good air quality, the excess energy used in
airflow would cost more than the filter is worth to change.
In general, it's better to change filters early, rather than late.
Internal air filtration is an increasingly critical component
of the energy-efficient facility. Accurate tracking of static
pressure via a building management system (BMS) will be a
significant component in any energy assessment.
With older buildings, an overall review of the filter
types, fan settings and system construction will reveal
valuable opportunities for energy savings that would be
comparable to LED lighting conversions.
Buying decisions should start with obtaining the right filter,
and conducting service changes at the appropriate time.
Supplier considerations should include stock availability,
breadth of range, credible support, warranty and overall cost.
Similarly, local and knowledgeable support is an important
factor when changes or upgrades are being considered.
The humble filter is often a forgotten part of the facility -- but the
people and equipment that it protects are critically important.
Is it time to change your filters?
Written by Dr Allan Heckenberg (PhD), BDM for Airepure
Filter ratings recommended for typical air contaminants and applications
Particle size / typical
Rating to EN
MERV Rating to
Typical filter type
>10.0 μm / pollen, dust mites,
Window A/C units, residential
Disposable panels, bulk media
5.0--10.0 μm / cement dust,
spray-paint, outside air dust
Industrial workplace, small commercial
buildings, outside air intakes
Disposable panels, bulk media
pads, pleated panels
3.0--5.0 μm / some bacteria,
Large commercial buildings, public
arenas, smaller shopping plazas
Pleated panels, deep bed bags
1.0--3.0 μm / legionella, sea salt
nuclei, auto emissions, lead
Shopping centres, data centres,
Pleated panels, multi-pocket
bags, mini pleat filters
0.3--1.0 μm / some bacteria,
asbestos dust, tobacco smoke F8-F9
Hospital environments, museums, clean
Multi-pocket bags, rigid
cartridge, box-type filters
© Airepure Australia Pty Ltd 2015
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