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Indoor Air Quality affects your bottom line in more
ways than one. Clients and customers feel better and
stay longer. Current, tougher legislation on indoor air quality has made it
more compelling than ever to clear the air of contaminants in every type of
business establishment. The purpose of this guide is to inform you of
available air cleaning technologies that meet today's clean indoor air
standards. With this information you can make an informed decision in
selecting the proper air cleaning system for your workplace.
Air cleaners use filters or electronic precipitators
to remove particulate contaminants from the air you breathe. Many air
cleaners also include a bed of sorption material to remove gaseous
contaminants, as well. Contaminants removed by commercial air cleaners may
include:
- Tobacco smoke
- Dust
- Airborne microbes
- Volatile organic compounds (VOC's)
- Pollen
Many manufacturers offer air cleaners as "stand alone"
units that include a fan for moving the air through the air cleaner. Other
units are designed for installation in the building's heating and cooling
system (HVAC system) and do not include fans.
-
Why
not just open a window instead of using an air cleaner?(Top)
- Unless you are fortunate enough to live
in an area where the outside air is always between 72ºF and 78ºF, you'll
waste the money spent heating or cooling the air in your home or
business.
- The air outside your home or business is
not always as clean as you'd like, especially in urban environments.
- Properly installed air cleaners generate
better airflow patterns for removing contaminants than just opening a
window.
1. Airflow
Volume(Top)
Obviously, the more air that is moved through an air
cleaner, the more air it will clean, if properly designed. Air cleaners are
usually rated in cubic feet per minute (CFM). This number tells you how much
air the machine will move.
How much airflow one needs is dependent on what's
going on in the room. As a general rule of thumb, in a smoky environment
(like a club, bar, breakroom, or lodge meeting hall) a 1,000 CFM machine
will be adequate for 1,000 square feet if the ceilings are 8' to 10' high.
The number of air cleaners required are determine by air changes per hour.
The following formula will help you determine how many air cleaners you need
for a given area.
a) How
to determine the number of air cleaners required:(Top)
Measure the size of the room in feet and use these
numbers in the following formula:
|
# of Air Cleaners =
|
L x W x H of room x Air
Changes per Hour |
| CFM of Air (see product literature)
x 60 min. |
|
|
|
L,W,H in feet |
b) Air changes
per hour (ACH):(Top)
|
|
ACH |
| light load |
(general offices, computer rooms,
conference rooms): |
4-5
|
| average load |
(bars, breakrooms, designated smoking
areas): |
6
|
| heavy load |
bingo halls, cigar bars, extra smoky
areas): |
8-10
|
2. Airflow
Pattern(Top)
The airflow pattern established by an air cleaner must
perform two tasks:
- Get the dirty air to the air cleaner
- Move the clean air throughout the room
Two basic designs are used to perform these tasks:
"Coanda" units move the air horizontally and
vertically similar to a reverse flow ceiling fan. They also take
advantage of the warm rising air and enhance this vertical movement by
pulling the air up with a fan. The airflow direction is changed as
the air passes through the machine and the clean air is blown out sideways
along the ceiling. This clean air strikes the walls (or the clean air from
other Coanda units in the room) and is circulated back down to the breathing
zone.
"Pass through" units take the air in one side and
exhaust the air out the other, horizontally. These units are often used in
pairs (or more) to establish a "race track" pattern of air movement around
the room at ceiling height. This airflow pattern takes advantage of the
normally rising warm air in commercial buildings to capture the dirty air.
Mixing of air by the race track pattern returns clean air to the breathing
area below. A "Pass through" air cleaner, operating by itself, will not
establish an effective air flow pattern. If only one air cleaner is going to
be installed in a room, the "Coanda" air cleaner would be the better choice.
3. Noise(Top)
All air cleaners make some noise as they move air
through the machine. The amount of noise is affected by design features such
as:
- Fan or blower speed (faster fans/blowers are
usually noisier)
- Fan blade or blower design
- Cabinet configuration (baffles and/or venturi
plates with bell-shaped orifices help damp out fan noise)
- Sound-adsorbent lining in the cabinet (Foam-like
materials are commonly used)
The noise levels generated by an air cleaner are rated
in decibels (dB). You can compare the dB ratings for machines that move
equivalent CFM to determine which is the quietest. In a well-designed unit,
the fan noise is no more noticeable than the noise of the HVAC system or an
office copier.
4.
Select an air cleaning technology that matches your needs.(Top)
Like any other machine, air cleaners are built
differently by different manufacturers. Understanding how manufacturers use
various technologies will help you decide which air cleaner best meets your
requirements. Technical features that will be important to your decision
include:
a.
Servicing the air cleaner(Top)
Any air cleaner must be serviced periodically if it is
to continue to provide satisfactory service. Servicing an air cleaner
involves one of three procedures:
- Replace the filter media (filter-type machines)
- Clean the collection cells (electronic machines)
- Replace the sorption beds (for machines so
equipped)
The collection cells, filters or adsorbent beds should
be easy to get to and remove.
Also, it is important to be candid about whether you'd
rather replace filters or clean collection cells. Consider the following:
- Filters are generally replaced less often than
cells are cleaned. However, filter replacement is an ongoing cost
- Collector cells make "Bug Zapper" noises if not
cleaned
- Filters clog up and stop the airflow if not
replaced. Also, filters can recirculate odors if not changed regularly.
Remember, properly designed and installed air cleaners
provide years of satisfactory service if properly serviced.
b. Energy
efficiency(Top)
Generally, electronic air cleaners are more energy
efficient than filter-type (media) air cleaners because they can use a lower
powered fan. That's because the electronic air cleaners offer
less resistance to airflow than the media air cleaners. Look at the amperage
ratings for the air cleaners you are comparing. If the CFM ratings are the
same, the air cleaner with the lowest amperage rating is the most energy
efficient.
c. Electronic air cleaner features(Top)
Electronic air cleaners work by passing the air
through an electrical field that puts an electrical charge on the particles
in the air. The air (along with the electrically- charged particles) then
passes through a "collector" that is made of aluminum plates. These aluminum
plates are also electrically charged. However, the charge on the collector
plates is opposite to the charge on the particles. Remember how "opposites
attract"? The electrically-charged particles are attracted to the collector
plates and stick on the plates until the plates are cleaned.
Voltage
doubler circuit(Top) - The
electrical field part of the air cleaner (the "ionizer section") requires
much higher voltage to be efficient than the collector section. The higher
the volts per inch, the greater the efficiency of the air cleaner until the
maximum voltage gradient of 20,000 volts per inch is reached. The level
cannot be exceeded or arcing (snapping) will occur. In order to reach the
highest efficiency possible while maintaining a compact collector section
with a large collection area for easy and less frequent cell cleaning, a
voltage doubler system (sometimes referred to as dual voltage) is employed.
The high voltage is used for strong ionization, while the collection section
voltage is dropped (roughly in half) in order to space collection plates
closely together for more collection area (longer service life) without
arcing thus achieving long service intervals, small package size, and high
efficiency. Air cleaners with this voltage doubler feature will generally
cost more; however the additional cost will be outweighed by less cleaning,
a more compact unit, and greater efficiencies in most cases.
Electronic cell construction(Top)
- The aluminum cell plates should be uniformly spaced and permanently held
in place by some durable means. Ceramic high-voltage insulators hold up
infinitely longer than plastic insulators. Cell plate area should be large
enough for a reasonably long service life, yet compact enough for easy
maintenance handling.
d. Media type air cleaner features(Top)
Media air cleaners work pretty much like the bag in
your vacuum cleaner or air filter for your car; the air passes through and
the dirt stays in the filter. Technical features that affect the performance
of media air cleaners are listed below.
Media area(Top)
- The media area for 1,000 CFM-range
commercial air cleaners ranges from 28 sq. ft. to 130 sq. ft. Generally, the
greater the media area, the greater the collection capacity. More media area
means less airflow restriction, thus less noise and energy consumption.
Perhaps most importantly, more media means the filters will last longer
before becoming plugged with contaminants.
Media efficiency(Top)
- Most 1,000 CFM-range commercial air cleaners are designed primarily for
tobacco smoke removal applications. Tobacco smoke requires a media with very
small pores in order to be captured because the particle size is so small.
Therefore, an 85% or 95% filter is normally used. The percentage is based on
the ASHRAE dust spot test. For extra hazardous or sensitive applications, a
HEPA (high-efficiency particulate arresting) filter is used. The D.O.P. test
is used to rate HEPA filters which are 99.97% efficient by definition.
5. Safety(Top)
It is very important that the air cleaner be designed
and manufactured to the highest safety standards. Underwriters Laboratories
Inc., founded in 1894, is a non-profit organization, established to
maintain, and operate laboratories for the examination and testing of
equipment to determine their relation to hazards to life and property.
Underwriters Laboratories publishes safety standards specifically for air
cleaning equipment.
Many state and local codes across the country require
a formal recognition, from an approved laboratory such as Underwriters
Laboratories (UL) or Inchcape Testing Services (ETL), that the air cleaner
is safe to operate.
Before you buy, be certain that the air cleaner is
recognized by UL or ETL.
6. Warranty(Top)
An air cleaner should be a long term investment,
designed to offer many years of service. Read the warranty. Most reputable
manufacturers offer a one to three year parts warranty. If a manufacturer
offers a warranty that is too good to be true, such as a lifetime warranty,
read it carefully. Find out how long they have been in business. Many times
these lifetime warranties require you to buy replacement filters at the
manufacturers recommended intervals to maintain the lifetime warranty. Read
carefully.
Summary(Top)
There is no doubt that an investment in clean air is a
wise and desirable step for your business. Employees will be happier
and more productive, customers will be more comfortable and stay longer. The
problem of the second hand smoke issue will be diminished as will the risk
of legal liability and medical compensation claims.
There are many choices to be made regarding the system
that will best fit your business. This guide is intended to provide general
information about air cleaning options for your business. If you would like
to further discuss your specific air quality issues with a trained
professional, please contact us
or use our information request forms found throughout our website by
clicking the "information request" button on the upper left of most product
pages. We stand ready to assist you in achieving your goal of clean
indoor air.
Thank you. |
