 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.
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 passthrough
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 4performance
are likely to significantly underestimate the effectiveness of such devices
under real-world conditions. Under most real-world conditions, air is recirculated
through central heating, air conditioning, and ventilation systems.
1.3 Specific Objectives
The specific objective of the tests described herein was to determine the effect
of the Electro Breeze Electronic Air Filter on the densities of contaminating
particles introduced into a recirculating 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 Breeze,
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 recirculation duct. Air was circulated
through the test duct using two backward curved impellers. Air was recirculated
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 recirculation 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 Particles per 0.1 CF
filter in place but without electronic activation.
The control experiment shows the same conditions, except
without the filter in place. While the particle densities
are slightly lower with the unactivated filter in place,
the differences are negligible. After 5 min of operation,
the particle density with the unactivated filter in place
was only about 2.1 percent lower than without the filter
in place. Within 5 min after the electronic activation
6 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 Breeze electronic air filter in an air duct
under recirculating conditions demonstrated effective removal of small airborne
particles when compared to a nonfilter 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.
Lifes Resources Inc. Lab Test Results For
Electro Breeze Air Cleaner. Here are the key highlights
of the test.
- 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 Breeze 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% f 0.3 micron.
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.
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