When searching to buy an air purifier, HVAC system, or vacuum cleaner, you may have come across the term HEPA Filter. Understanding what a HEPA filter is and how it works will provide a better understanding of what they are and insight into how they compare to other High-Quality Air filter products.

What Is A HEPA Filter?

HEPA is an abbreviation for high-efficiency particulate air, often known as air filtration. It implies that a filter must reach a certain efficiency in order to fulfill the HEPA standard. When referencing efficiency, it usually means a HEPA grade of H13 or H14.

H13-H14 HEPA filters are deemed medical-grade and are in the highest class of HEPA air filtration. This sort of air filter can potentially remove 99.97 percent of dust, pollen, mold, germs, and any other airborne particles larger than 0.3 microns. The diameter standard of 0.3 microns addresses the worst-case scenario; the particle size with the greatest penetration (MPPS). Particles that are bigger or smaller are trapped more effectively. Using the worst-case particle size yields the worst-case efficiency rating, such as 99.97 percent or higher for all particle sizes.

It is important to note that Europe’s H ratings should not be confused with MERV ratings in the United States. For example, in Europe, HEPA H13 and H14 are roughly equal to MERV 17 or 18 in the United States.

Where Do HEPA Filters Originate From?

Though the HEPA standard and certification process were not established until 1983, the development of HEPA filters goes back to World War II, when American scientists with the Manhattan Project developed the first HEPA filter to prevent the spread of airborne radioactive contaminants, which was later commercialized in the 1950s. After World War II, the Atomic Energy Commission (AEC ) chose the military’s HEPA filters for the removal of air particles in all nuclear facility air exhaust systems.

What Types of Particles Can a HEPA Filter Remove From the Air?

The HEPA standard captures very minute particles, including viruses and bacteria, undetectable to the naked eye yet detrimental to our health. In addition, because the web of fibers in a medical-grade HEPA filter is so thick, it can catch the tiniest particles at the maximum rate and is more effective at eliminating dangerous poisons from the environment.

For perspective, a human hair is approximately 80 to 100 microns in diameter, pollen is 100-300 microns, and a virus ranges in size from >0.1 to 0.5 microns. Viruses frequently cling to small dust particles; therefore, bigger particles in the air may also contain viruses. You capture them all with a 99.95 percent effective HEPA filter.

What are the Different Types of HEPA Filters?

HEPA filters exist in various shapes and sizes, with different grades, classes, or MERV system ratings. The Department of Energy is responsible for establishing the guidelines; however, the type of HEPA filter can vary for each manufacturer.

HEPA filters are classified into multiple categories based on the filters ability to filter out microscopic particulate matter (PM) ranging from 2.5 PM to 10 PM. The benchmark for determining this is based on the filter’s performance for the most challenging, or most penetrating particle size (MPPS). This categorization system is identified with letters and numbers and the filters are separated into eight different classes ranging from H10 to U17. The classes are determined on the effectiveness of the media at the MPPS and the magnitude of any flaws or leaks of each product. (Source: Science Direct)

A Minimum Efficiency Reporting Value (MERV) grade indicates a filter’s capacity to catch bigger particles with diameters ranging from 0.3 to 10 microns. The rating is based on a test technique devised by the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE). The greater the MERV rating, the more effective the filter is in trapping specific sorts of particles.

Filter Mechanisms

Most HEPA filters nowadays are comprised of an interwoven mesh of glass fibers. Particles are caught in four ways: Inertial Impaction, Diffusion, Interception, and Sieving.

Inertial Impaction: Large particles go in a straight path, collide, and become imprisoned when they encounter.
Diffusion: As smaller particles move, they collide with the fibers and are collected.
Interception: Mid-range particles follow the air flow stream as it goes through the spaces of the filter and are captured when they touch the fibers.
Sieving: Sieving occurs when a particle is too big to fit between the gaps in the fiber.

Where Are HEPA Filters Used?

HEPA filters have changed through time and are now used in various industries. Some of the products HEPA filters can be found in are mentioned below. Depending on the firm or manufacturer, the type of filter utilized varies.

Air Purification Systems
Face Mask Material
Vacuum Filtration
Airplanes
Cars
HVAC Filters

Is it possible to update an existing HVAC unit to HEPA?

It is possible to to update an existing HVAC unit to HEPA filtration, however, because of the increased pressure the filter element has, it may be challenging to install a HEPA filter in an existing HVAC system. It would be more beneficial to use a high quality filter that has the same benefits as a HEPA filter. Quality filters with a MERV rating of 11 to 16 can be used in an existing HVAC system, based on the manufacturers recommendation.

Thanks for Reading!

Just as a HEPA filter can capture particles such as smoke, dust, bacteria, viruses, pollen, and other contaminants, high-quality HVAC filters for home and commercial use can also capture these particulates. Choosing the right filter for your home or business is an important decision to make as it impacts the indoor air quality you breathe. At Filti, our filtration products can capture up to 95% of bad air particulates include bacteria, viruses, and VOCs. Filti filters are manufactured in the United States, using our nanofiber technology. It is our mission to provide the best air filters available to help ensure clean air. Check out our website for more information on Filti, our mission, and our products.