Home / A Comprehensive Guide to HEPA Filters
HEPA filters, those unassuming but crucial components in air filtration systems, play a pivotal role in maintaining healthy indoor air quality.
What Are HEPA Filters?
HEPA filters stand for High Efficiency Particulate Air Filters.
These filters are designed to capture and remove particles from the air, which trap the tiniest and most harmful contaminants.
In the United States, for instance, HEPA filters must remove at least 99.97% of particles as small as 0.3 microns in diameter. These stringent criteria ensure that HEPA filters truly deliver on their announced high efficiency.
Do HEPA Filters Remove Odors?
Even though HEPA filters are highly effective at capturing particles and microorganisms, they are not designed to remove odors on their own. HEPA filters primarily focus on the mechanical filtration of airborne particles based on their size.
Odors, on the other hand, are typically composed of volatile organic compounds (VOCs) and gases. Filters that can effectively remove odors typically contain activated carbon or charcoal as the key filtration media.
Activated carbon filters are highly effective at adsorbing and trapping volatile organic compounds (VOCs), gases, and odorous molecules.
How Do HEPA Filters Work?
HEPA filter lies a complex web of fibers. As air flows through this dense maze, particles—whether large like pollen or minuscule like bacteria—are trapped. The efficiency of a HEPA filter is attributed to three primary mechanisms: interception, impaction, and diffusion.
Interception
Interception occurs when particles traveling with the airstream come within one particle’s radius of a fiber in the filter. These particles are then intercepted or captured by the fiber.
As air flows through the filter, larger particles are more likely to be drawn toward the fibers due to the airstream’s flow lines. Once these particles come in close proximity to a fiber, they adhere to it, effectively getting removed from the airstream.
Impaction
Impaction is the process by which larger particles, unable to follow the curving contours of the air stream around the filter fibers, embed directly into the fibers.
As the air velocity increases, so does the likelihood of impaction. In HEPA filters, the dense maze of fibers ensures that the air path is tortuous. Larger particles, due to their inertia, cannot adjust to the sudden changes in airflow direction and end up colliding with the fibers.
Diffusion
Diffusion is the mechanism responsible for capturing the smallest particles, typically those below 0.1 microns in diameter.
Small particles move erratically due to Brownian motion—a phenomenon where particles in a fluid (in this case, air) move in a random fashion because of collisions with molecules. This erratic movement increases the chances of these particles coming into contact with filter fibers. Once they do, they adhere to the fibers and are removed from the airstream.
Where HEPA Filters Are Used?
Healthcare Facilities:
HEPA filters are a vital component in the HVAC system of cleanrooms and operating rooms in hospitals. They help maintain sterile environments by trapping bacteria, viruses, and other airborne contaminants, thus preventing the spread of infections.
Pharmaceutical Industry:
In pharmaceutical manufacturing, HEPA filters are used in production areas to maintain the purity of medicines and prevent contamination of sensitive drugs and the production process.
Biotechnology:
Laboratories working with delicate biological samples require HEPA filtration to safeguard experiments from contamination.
Automotive:
HEPA filters in the vehicle industry enhance manufacturing air quality on the site, trapping pollutants and harmful particles.
Residential and Commercial HVAC Systems:
HEPA filters are integrated into HVAC systems to remove allergens, dust, and particulate matter, providing cleaner indoor air for homes, offices, and other public spaces.
Food Processing:
In food processing facilities, HEPA filters are employed to maintain hygiene, prevent contamination, and ensure product safety.
How Long Do HEPA Filters Last?
The lifespan of a HEPA filter varies based on several factors, including the specific type of filter, the environment in which it’s used, and the volume of contaminants it’s exposed to.
The efficiency of the pre-filter or the filter before the HEPA filter stage is also among the important factors that influence HEPA filter service life.
The higher the efficiency of prefilters or the early stage filters, meaning fewer contaminants will reach the HEPA filter, the longer lifespan the HEPA filter will have.
Residential Applications
In a typical home setting, a standard HEPA filter can last anywhere from 12 to 18 months. This duration can be shorter if the home environment has higher levels of dust, pet dander, or other airborne particles.
Commercial or Industrial Use
In commercial or industrial settings where the air might be more polluted or where the filter is used more frequently, HEPA filters may need replacement every 6 to 12 months.
Can HEPA Filters Be Washed?
Photo by: Shafer Services
When it comes to changing HEPA filters, a question always comes up: can you clean HEPA filters?
HEPA filters are made with delicate and intricate arrangements of fibers, which can be damaged during cleaning. They are not designed to be washed or cleaned in the traditional sense.
Attempting to wash a HEPA filter can damage the integrity of the structure, leading to loss of function and reduced filtration efficiency.
Replacing the HEPA filters when they become clogged or reach the end of their service life is more cost-effective than cleaning them.
Conclusion
HEPA filters boast unparalleled filtration efficiency, capturing minuscule particles as tiny as 0.3 microns at a remarkable 99.97% rate.
This comprehensive filtration prowess extends to allergens, dust, pet dander, bacteria, and even viruses, ensuring that your indoor environment remains virtually free from harmful contaminants.
CleanLink offers a wide range types of HEPA air filters for your needs. For those customers who need special filter designs or solutions, we have custom services available. Feel free to talk to our filter experts for a custom solution.
