View A Video on Air Filters- A Quick Introduction
Air filters are devices used to minimize or remove unwanted particulates from the air flow within a ventilation system or space to improve air quality and to extend the working life of machinery, engines and appliances. Filters are typically composed of a fibrous material which is constructed in a screen through which air is moved. Air filter manufacturers design air cleaner filters for different needs and filtration standards. The particles to be removed from the air can range from dust to pollen to mold spores to animal dander and other unwanted molecules carried by air. Types of filters include inline filters, membrane filters, air compressor filters, HVAC filters and more which are simply constructed devices incorporated into a wide variety of everyday applications. Specialty filters such as carbon air filters or exhaust filters can be used to remove other contaminants such as gases and odors from air streams. In medical applications, filters can be used to remove bacterial and viral microbes and infections which are transported through air molecules. HEPA air filters and ULPA filters provide the highest level of filtration, while other filters such as foam filters or vacuum filters provide lower levels of air purification but are perfectly adequate filters for many applications. Electrostatic filters provide an almost permanent filtration screen solution and do not require a power source in order to be most effective. Most types of filters can be custom fabricated to an extent in order to meet specific requirements.
When determining the most suitable type of filter to use for any given application, there are a number of factors to consider. Filtration efficiency is determined by the size of the material fibers and their length, as well as the density with which filter fibers are placed within the filtration unit. Dense filters will capture more particles and therefore provide a higher level of air purification, however will require more power in order to push the air through the filter. Therefore air velocity is another factor to be considered. Air filter manufacturers use various materials to make the variety of air filter types available. Fabrics, for example, are used in many types of filters such as membrane filters or paper can be used as a disposable filter option. Metals such as stainless steel are also constructed into filter screen for heavier duty filtration requirements. Alternatively other filters, such as carbon air filters utilize chemical reactions within the filter itself to attract and remove harmful elements from the air. Plastics are used in electrostatic filters to create the natural static charge from friction which attracts dust particles. There are specific air cleaner filters available for different needs, for not all filters are designed to remove the same particles.
HVAC filters are largely used in home or commercial heating ventilation and air conditioning systems (HVAC). The more researchers learn about harmful particles and substances that exist in the air, the more air filters play an important part in society's long-term health. Particularly beneficial is the use of air filters in domestic environments in which there are pets or excessive mold, mildew and dust that bring on allergic symptoms. Air filters help clean the air and remove these allergy-causing particulates, thus allowing home-owners and their families to breathe easier. The incorporation of filters into a circulation system is especially important for those prone to asthma or persons with breathing difficulties. A HEPA (High Efficiency Particulate Air) filter is an example of a specific style of filter used in HVAC systems which is able to remove the highest amount of unwanted particulates from an air stream. A HEPA air filter is mainly used to remove miniscule particulates such as allergens and other common irritants from the air and therefore is commonly used in critical applications such as hospital operating rooms and pharmaceutical facilities. ULPA filters are also highly efficient and very common. HEPA and ULPA filters are commonly used to eliminate harmful allergens. Strict air quality guidelines in many government and industrial circles make the use and continued innovation of air filters essential.
In addition to these uses, the automobile industry uses air filters extensively in vehicles to help promote engine hygiene. Exhaust filters and inline filter are common engine components. Some domestic and industrial appliances house their own internal air filters to increase air quality. Clean air within individual machines ensures longer life to the units. Examples of these types of air filters are found in vacuum cleaners and humidifiers. Air filter manufacturers create their products to protect machines like cars and air conditioners from damage and premature breakdown. Air compressor filters, for example, are vital to the longevity of direct air machines such as nail guns. For the most part, air filters that deal with large particles and high velocities have large filter fibers, and likewise, air filters that deal with small particles and low velocities have small filter fibers. To ensure that an air filter will work properly in its intended application, make sure that the design, density of media and fibers and possible adhesive are taken into account before purchase. Air filters are generally able to function very well, as long as they handle the right kind of particulate for their design. If well maintained and regularly cleaned, many filters will outlast their intended replacement date and will provide years of reliable performance and cleaner air.
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Types of Air Filters
- Air cleaner filters remove
a range contaminants from the air.
- Air compressor filters, or compressed air filters, are essential elements to air compression systems that removing water, oil, dust, vapors and other contaminants from a compressed air supply.
are air filters that can handle rapid movement of air through a confined
space. Automobile intake filters are often made of fibrous materials
that allow the air to flow as freely as possible, yet capture essential
are filters that are treated with an antimicrobial agent, which prevents
growth on the filter media.
- Carbon filters
use carbon, a natural, non-metallic material that is very effective
for removing gases and odors. Also called "active" or "activated
carbon filters," these filters are particularly suitable for
removing chemicals from the air, because carbon can absorb up to
60% of its own weight in gas.
have various components with different temperature limits and are used
in applications that need a temperature resistant material.
are used in conjunction with a compressed air system. These systems
are often utilized in workshops and warehouses in which high pressure
air is used as a cleaning and dust removal tool.
work by charging the dust particles in the air, which attracts them
to the metal plates in the filter.
- Exhaust filters remove impurities from air that is drawn through a ventilator, thus cleaning it so it may be returned to normal circulation.
are made up of tiny interlocking cells that trap and distribute dirt
particles throughout the entire volume of the foam. Foam filters are
often used in automobile intake systems.
are used to filter the air from hazardous gasses.
attract grease laden air away from heat sources, such as commercial
ovens. Grease filters are often made of stainless steel.
- were originally designed to prevent
discharge of radioactive particles from nuclear reactor facility exhausts.
These filters are now widely used in industrial settings because of
their high efficiency of capturing a wide range of air contaminants.
- HVAC filters
- Inline filter
- Membrane filters are thin microporous films employed to trap or retain particulate impurities from an air source that is drawn through them.
are used in spray booths to remove waste paint and dust particles from
are filters that are folded to allow for more surface area to be exposed
within a smaller area of a filter frame.
- ULPA filters are ultra-low particulate air filters meaning that they can remove extremely small particles from the air in order to purify it.
- Vacuum filters maintain air quality and mechanical functionality by removing impurities from the air that is circulated through a given machine and then expelled.
Air Filter Terms
The retention of gas, liquid or solid on a surface due to positive interaction/attraction
between the surface and the molecules of the adsorbed material.
- A term that refers
to any particles or substances floating in the air.
- A current of air.
- A normal substance
that causes an acute defensive reaction in a person's immune system.
- An air filter's
ability to remove synthetic dust from the air during a test.
- A backward surge
of pressure from downstream to upstream of an air filter. Backpressure
can be the result of closing a valve or air entrapped in a liquid system.
professional designation available through training and testing by the
Association of Energy Engineers (AEE).
of chemicals used as refrigerants, being tightly regulated and phased
out of production due to stratospheric ozone depletion potential. Examples:
R-11, R-12, R-113, R-114, R-115.
- The prevention
of an agent from being transmitted from one point to another.
- An unwanted
intrusion, such as harmful airborne particles.
- The removal
of unwanted airborne particles to neutralize the air.
- The permeable
material that removes particles from a substance being filtered.
passing through an air filter without being removed from the air stream.
- The product that
- A term
that refers to the amount of pollutants in the air within a confined space.
- A filament, grid or
porous body in an ion engine or other device that strips an electron from
the outer shell of a neutral atom to form a positively charged ion.
- A continuous matrix
with pores of defined size.
in an area that is responsible for the inflow of air.
- A molecule containing
three atoms of oxygen. Ozone is harmful to both humans and plants at ground
level, but is crucial in blocking ultraviolet radiation in the stratosphere.
- A very small solid
suspended in air or water that can vary in size, shape, density and electrical
in an area that is responsible for the outflow of air.
- In the case
of air filters, a measure of the resistance of air to flow through a filter.
- The direction that
is in opposition to the airflow.