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How Air Filters Work? A Complete Guide to MERV Rating & HEPA Filters

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An air filter is a standard element in any HVAC system. However, MERV and HEPA filters are two of the most popular filters on the market. All air filters are designed to trap airborne particles and ensure clean indoor air. Dust particles, mold spores, bacteria, and particulate matter can contribute to poor indoor air quality and lead to poor health for those breathing the air. MERV and HEPA filters seek to eliminate these dangerous particles but knowing the difference between the two can be confusing. While HEPA filters have a MERV rating, not all MERV rated filters are HEPA filters. We are going into depth on the differences between the two and how they filter out harmful particles so you can make the best decision for your facility. 

MERV Rating

Filters that are MERV rated refer to the minimum efficiency reporting value (MERV) rating used to categorize air filters. This rating system can be a helpful tool in deciding which air filter is best for your facility. Based on a filter’s ability to capture particles, they are assigned a MERV rating from 2 to 20. The higher the rating, the better it captures tiny airborne particles. MERV rated filters can be used in various settings but are often found in commercial and industrial buildings. This budget-friendly option can help provide healthier indoor air quality. 

How MERV Rated Filters Work

All MERV rated filters work to prevent contaminants from leaving the filter and entering back into the indoor air. Its methods will differ based on the MERV rating. One thing to note is that a higher rating does not necessarily mean it is the best option for your facility. Highly rated filters have small pores, making it more difficult for air to pass through. Some HVAC systems are not prepared for any resistance and can harm the overall system. 

What Is Filtered Out at Each Level

MERV 13 through 16 are designed to remove particles larger than 0.30 micrometers. While numerous kinds of particles are included in this size, pollen, dust mites, mold spores, tobacco smoke, and auto fumes are some of the most notable. Meanwhile, MERV 17 through 20 can filter out particles that are less than 0.30 micrometers in size. This includes radon, combustion smoke, virus carriers, coal dust, sea salt, and microscopic allergens. While these lists are not comprehensive, it can give you a good idea of what types of particles each MERV rating can filter out. 

HEPA Filters

If you only want to target small particles, a high-efficiency particulate air (HEPA) filter would better suit your needs than a MERV rated filter. These pleated mechanical air filters are the most effective filter on the market, making it an ideal choice for hospitals and other medical facilities. Its unmatched ability to filter germs and viruses makes it a popular choice for operating rooms. By the tightly interweaving glass and synthetic fibers, medical-grade HEPA filters ensure that only the tiniest of particles escape through the filter. 

How HEPA Filters Work

HEPA filters' unique design might not be compatible with your current HVAC system. A standalone HEPA air filtration system is often needed for it to operate properly. Once you have the necessary devices, a HEPA filter traps the tiny particles through one, or a combination, of these methods. 

When particles crash into the surface of the filter and are captured, this is known as impaction. Particles that are larger than 1 micron, and are bigger than the mesh openings of the filter’s screen, are targeted in this method. When particles pass through the screen without being captured, interception is the next attempt at attacking the particles. As they continue to pass through the filter, the particles will collide with fibers and are removed from the air. This is known as an interception. 

The final attempt to eliminate harmful particles is diffusion. The tiniest particles are targeted in this step. Gas molecules will collide with the particles, causing erratic movement within the filter. As this happens, the particles will crash into the fibers and stick, preventing them from re-entering the air within the facility.  

What Is Filtered Out at Each Level

All HEPA filters target particles smaller than 0.30 microns at a 99.97% efficiency. A HEPA filter is considered to have a MERV rating of 17 or higher, depending on the individual filter. HEPA filters also have their grading system, with H13 and H14 medical-grade HEPA. Dangerous particles like pollen, dust, mold, and bacteria can all be successfully removed with a HEPA filter. 

How These Filters Are Beneficial for Your Facility

Upgrading your air filters is crucial to ensure the people in your facility remain safe and healthy. Air filtration systems that utilize MERV or HEPA filters can help with infection control and dust contamination. Taking proactive steps to ensure quality indoor air can greatly reduce health risks and increase productivity. Steps not taken to regulate indoor air quality can result in coughing, sneezing, asthma attacks, respiratory diseases, heart attacks, and even cancer. You can just set your mind at ease and limit the time you spend worrying about the health of those within your facility by using air filters to eliminate harmful particles and dust. 

Why Choose HEPACART®

HEPACART provides air filtration solutions to help keep your staff and visitors safe from harmful airborne particles. Our products are tested and HEPA-certified to ensure you only receive the best air filtration devices. We want to help you save time and money by ensuring all of our products have an extended life so your facility remains protected. Are you interested in purchasing a HEPACART product for your facility? Download our transparent pricing guide today!

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