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ELECTRO-FILTER™
Test Results.
Effect of the Electro-Filter Air Filter on Airborne Particles in a
Re-circulating Air Duct
Prepared July 14, 2003 by:
Kerby F Fannin, M.P.H., Ph.D., CES
Certified Environmental Specialist
Electro-Filter Air Cleaner Ltd. Report No. 8126-03-1
Life’s Resources, Inc.
1” ELECTRONIC PANEL FILTER
Electro-Filter Air Cleaner Report No. 8126-03-1
July 14, 2003
Life’s Resources, Inc.
1.0 Introduction
1.1 Purpose
The purpose of these tests was to determine the effect of the Electro-Filter Electronic Air Filter on airborne
particles contained within a re-circulating air duct.
1.2 Background
Air is an important vehicle for transmitting particles of respiratory significance from sources to humans. Such
particles may contain irritating materials, hazardous chemicals, or infectious and allergenic microorganisms.
Reducing the levels of airborne particles in occupied spaces can lower exposure of susceptible persons to such
airborne contaminants. Levels of airborne particles can be reduced by either eliminating air-contaminating
sources or reduce the densities of the particles in the air.
The use of air filters that capture particles of
respiratory significance can be an important method of removing particles that are introduced into the air from
existing sources. Numerous devices have been developed and marketed for the purpose of removing particles from the air in
indoor environments. These units operate on principles that include electrically neutral and electrically
charged media filtration, electronic precipitation onto collecting plates, electrostatic precipitation, ozone
generation, particle ionization, and others.
Existing
air cleaning devices operate with varying levels of
effectiveness. Standard methods have been developed for evaluating conventional air cleaning devices,
included electrically neutral filters.1 2 The standard methods for evaluating air-cleaning devices typically
employ evaluation under once-through conditions. Consequently, these methods are especially useful for
evaluating mechanical air filtration devices using a single pass-through of air containing contaminating
particles.
Some air cleaning devices, such as those using electronically charged fibrous media, impart polar ionic
charges to particles that pass through the charged media. This particle polarization, under certain conditions,
enhances particle agglomeration and subsequent mechanical removal during multiple passes through the
device. Consequently, the effectiveness of the devices that operate by agglomeration increases as particles are
re-circulated in the air stream. Therefore, standard tests that are based on one-pass rather than on multiple-pass
performance are likely to significantly underestimate the effectiveness of such devices under real-world
conditions. Under most real-world conditions, air is re-circulated through central heating, air conditioning, and
ventilation systems.
1 ASHRAE
Standard 52.1-1992, Gravimetric and Dust-spot Methods for Testing
Air-cleaning Devices Used in General
Ventilation for Removing Particulate Matter (ANSI Approved) American Society
of Heating, Refrigerating
and Air-Conditioning Engineers, Inc., Atlanta.
2
Standard 52.2-1999 -- Method of Testing General Ventilation
Air-Cleaning Devices for Removal Efficiency
by Particle Size (ANSI approved), American
Society of Heating, Refrigerating and Air-Conditioning Engineers,
Inc., Atlanta.
1.3 Specific Objectives
The specific objective of the tests described herein was to determine the effect of the Electro-Filter
Electronic Air Filter on the densities of contaminating particles introduced into a
re-circulating air stream compared to the control condition, without the test filter in place.
2.0 Test Equipment and Methods
2.1 Test Air Filter
The test filter was an electronic air filter manufactured by Electro-Filter, St-Sauveur-Des-Monts, Quebec,
Canada. The unit had dimensions of approximately 12 in. x 24 in. x 3/4 in. and operated by applying a
high voltage charge to a disposable fibrous electronic filter media. The unit was operated using a 24-volt AC
transformer and with a high voltage probe that was in contact with a center screen. The frame attached to
outside screens was in contact with an electrically grounded surface during operation.
2.2 Test Duct
The test duct consisted of an electrically grounded steel ventilation duct of 1 x 2 ft attached via duct
transitional adapters to an approximately 21 ft x 10 in diameter galvanized steel
re-circulation duct. Air was circulated through the test duct using two backward curved impellers. Air was
re-circulated through the test portion of the air duct at an average face velocity of approximately 270 fpm. Ambient relative humidity of 70
percent and temperature of 77° F were determined using a wet and dry bulb
psychrometer.
2.3 Smoke Introduction
Cigarette smoke (Pall Mall, Brown & Williamson Tobacco Corporation, Louisville, KY) was introduced into
the test duct by placing the one end of a cigarette in a specially designed holder located on an outside wall of
the duct approximately 2 ft upstream from the test filter location. After air
re-circulation was started, the cigarette was lit and “smoked” into the air stream for five minutes. The cigarette smoke remaining outside the
test chamber was collected and ducted to a high efficiency HEPA air cleaner. After five minutes of cigarette
smoke introduction into the test chamber, the cigarette was removed and extinguished and the hole was
sealed.
2.4 Air Sampling
Airborne particles were monitored for micron and submicron particles using a Met-One Model 227B-EL laser
particle counter (Met- One, Grants Pass, OR). Particles in two different size ranges, 0.3 µm and 1 µm, were
simultaneously monitored. Particle measurements were made at an air sampling rate of 0.1 cfm and recorded
at 1-min intervals, allowing for a 5-sec response time. Samples were taken approximately 2-in downstream
from the test filter.
3.0 Results
The density of 0.3 µm airborne particles with the test air filter in place was compared with that without the air
filter in place. The initial comparison was made during the first 5 min of operation during smoke introduction
into the chamber. During this initial 5-min period, the test experiment shows the particle densities with the
filter in place but without electronic activation. The control experiment shows the same conditions, except
without the filter in place.
Tip:
When reading the charts, the maroon color is with the Electro-Filter not plugged
in, which is still more efficient than standard furnace filters. The blue
colored bars are with the electro filer running.
While the particle densities are slightly lower with the
deactivated filter in place,
the differences are negligible. After 5 min of operation, the particle density with the
deactivated filter in place
was only about 2.1 percent lower than without the filter in place. Within 5 min after the electronic activation
of the test filter and cessation of smoke introduction, the particle density decreased by approximately 97.8
percent compared to the control.
The density of 1 µm airborne particles with the test air filter in place was compared with that without the air
filter in place. The initial comparison was made during the first 5 min of operation during smoke introduction
into the chamber. During this initial 5-min period, the test experiment shows the particle densities with the
filter in place but without electronic activation. The control experiment shows the same conditions, except
without the filter in place.
The differences in the initial air densities were much greater for the 1 µm than for the 0.3 µm particles. After
5 min of operation, the particle density with the unactivated filter in place was about 25.3 percent lower than
without the filter in place. This suggests greater physical removal of the larger sized particles by filtration
through the filter media. Within 4 min after the electronic activation of the test filter, the particle density
decreased by approximately 99.7 percent compared to the control.
4.0 Conclusions
Tests performed on the Electro-Filter electronic air filter in an air duct under
re-circulating conditions
demonstrated effective removal of small airborne particles when compared to a
non-filter control. Activating
the electronic air filter significantly increased the reduction of 0.3 and 1 µm particles generated from tobacco
smoke when compared to the control. After a 5-min period of introducing smoke into the test duct, operation
of the electronic filter for 5-min showed a 0.3 µm particle reduction by 97.8 percent compared to the control.
After a 5-min period of introducing smoke into the test duct, operation of the electronic filter for 4-min
showed a 1 µm particle reduction by 99.7 percent compared to the control.
Here are the key highlights of the test.
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The air cleaner without electronic activation removes some particles.
-
However, when the air cleaner is electronically activated, there is a significant reduction of particles,
99.7% reduction, after 4 minutes of air flow through the chambers.
-
The difference between an air cleaner non activated and electronically activated is extraordinary.
-
Extrapolating from the lab test chambers, we can conclude that any environment can effectively be
cleaned of polluting particles of micron and sub-micron sizes using our multi-pass electronic air
cleaner.
-
In a home of 2,000 SF with a 9’ ceiling (18,000 cubic feet), a furnace or air conditioner working on
1200 cfm (cubic feet per minute), (18,000/1200cfm). There are four complete passes or air changes in
an hour. We can conclude that the air has been cleaned similar to the test chamber results. Continuous
air flow assures the continuous removal of polluting particles.
-
The same principle of air cleaning applies to all environments.
-
Offices, businesses, buildings, plants can all be air cleaned with proper air handling and using
Electro-Filter electronic air cleaners.
-
The labs of Lifes Resources have proven the superior performance of electronic cleaners. It is a
known fact that particles smaller than 1 micron are much more numerous and more harmful to our
health than larger particles. The tests, run by the labs of Lifes resources, prove that our electronic air
cleaner cleans the air to over 97% of 0.3 micron.
ECONOMICAL
- Electro-Filter air cleaners cost just pennies per month to operate.
Further, by keeping your ducts and heating and cooling equipment cleaner, your
entire system will run more efficiently. Take
advantage of our introductory offer, for a limited time, order and get 4
FREE furnace filter pads. That's a 1 year supply of furnace filters for FREE!
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