A Look at True HEPA Filters
HEPA, which is an abbreviation for high efficiency particulate air, is a filtration technology designed during the Manhattan Project to prevent radiation from escaping the labs. Nearly seven decades later, it is still the most sophisticated form of air filtration available. That coupled with its low cost and accessibility makes it the filter medium of choice for hospitals, datacenters, military installations and even residences throughout the world.
Due to this popularity, HEPA has become a buzzword, and various marketing uses of that word complicate the issue: a HEPA filter, a medical-grade HEPA filter, a HEPA-rated filter, a HEPA-type filter and so forth. Despite all of this confusion, there is an extremely specific definition of what a true HEPA filter is. The various uses of the word HEPA are typically manufacturers of lesser filters using clever wordplay to bolster the attractiveness of their product to consumers.
In order to be true HEPA and carry the label ‘HEPA filter,’ the U.S. Department of Energy (DOE) publishes guidelines. The guidelines are extensive, but we’ll cover the most important points.
A true HEPA filter must be able to trap 99.97-percent of all airborne particulate matter that is at least 0.3 microns in diameter. To put this in perspective, consider that the diameter of a human hair is approximately 70 microns. There are also specific rules for fiber arrangement. A manufacturer must arrange the fibers in a true HEPA filter precisely so that it properly performs three specific tasks: interception, impaction and diffusion.
- Interception: This is where particles following a line of flow in the air stream come within one radius of a fiber in the filter and adhere to it. This the first line of defense, and it causes most particles to adhere to the filter fibers.
- Impaction: This is where larger particles are unable to avoid fibers by following the curving contours of the air stream and are forced to embed in one of them directly. This effect increases with diminishing fiber separation and higher air flow velocity.
- Diffusion: This is where particles that are too small for either interception or impaction are trapped by forcing them to collide with the surrounding gas molecules.This impedes and delays their path through the filter. This behavior is similar to Brownian motion and raises the probability that a particle will be stopped by either of the two mechanisms above. This mechanism becomes dominant at lower air flow velocities.
Today, HEPA filters are widespread. One of the most popular uses is in vacuum cleaners. Since vacuums kick up quite a bit of dust and other particulates, these filters are quite helpful to those with asthma and severe allergies.
Many people also use portable true HEPA air purifiers in their home. The benefit of a portable unit is that you can move it to wherever the activity is or where you’re sleeping, and in that way, you experience the benefits immediately.
In the introduction, we mentioned hospitals. Hospitals are some of the most notable consumers of true HEPA air purifiers. In fact, hospitals in Hong Kong used premium-grade air purifiers from IQAir to combat the deadly SARS epidemic. Most hospitals throughout the world use HEPA to eliminate airborne allergens, pollutants, and disease-causing microorganisms (like bacteria and viruses).
In most residences, a HEPA air purifier is enough to promote health and to ensure clean air. A HEPA air purifier can help provide significant relief to asthma and allergy sufferers because it removes toxic dust, dust mites, mold spores, pollen and so forth from the air. An air purifier that features a true HEPA air purifier can prove beneficial to those people with particularly severe cases of allergies and asthma by removing airborne allergens. A true hepa air purifier will improve the indoor air quality of your home. Stop breathing that poisonous air and start ensuring a better tomorrow for you and your family.
Clean Air Plus is a veteran and family owned small business. We represent the leading manufacturers in HEPA filtration including Austin Air Standard Units, Austin Air Junior Units, IQAir, Amaircare, Oransi and Airpura. Shop online or call one of our friendly experts at 888.247.1147. We'll be happy to help you choose from our large selection of quality air purifiers.
- Administration Staff