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How Does a HEPA Filter Work?

Table of Contents

In today’s world, air pollution and worsening air quality keeps air filtration top of mind.

Types of HEPA Filters

HEPA, which stands for High-Efficiency Particulate Air, is a designation used for filters that meet a specific standard in removing particles from the air. True HEPA filters trap and remove air particles that are small in diameter, and that can unknowingly damage the indoor air quality. There are several HEPA types, each designed for specific applications:

  • Portable HEPA air filters: These small, standalone units are designed for individual rooms or small spaces. They are often used in bedrooms, offices, or other areas where people spend significant time.
  • Whole-house HEPA air filters:These filters are integrated into a home’s HVAC system, providing HEPA filtration to the entire house. They are ideal for those with allergies or respiratory issues who need clean air throughout their living space. 
  • Industrial HEPA air filters: These heavy-duty filters are used in commercial office buildings, retail spaces, and industrial settings such as medical facilities, laboratories, and manufacturing centers. They are designed to handle large volumes of air pollution and filter the smallest particles.

How HEPA Filters Purify Air

These filters are highly effective indoor air quality solutions thanks to their unique design and filtration mechanisms. A dense mat of randomly arranged fibers is at the core of a HEPA filter, and these fibers trap particles as they pass through the air. The filtration process involves three main mechanisms: inertial impaction, interception, and diffusion. Let’s explore the mechanics of how these filters actually work:

  • Inertial impaction: Large air particles collide with the filter fibers and become trapped.
  • Interception: Mid-sized particles come close enough to the fibers to adhere to them as they pass by.
  • Diffusion: Small particles move erratically, increasing their chances of contacting and sticking to the fibers.
  • Depth filtration: As particles accumulate on the fibers, they create a denser web that continues capturing nanoparticles and enhancing the filter’s effectiveness over time.
  • Airflow resistance: The fiber network in the filter creates significant airflow resistance, giving particles time to be captured by the air purifier.
  • Multi-stage filtration: Depending on the HEPA type, many HEPA filtration systems incorporate pre-filters to capture larger particles before they reach the filter, extending its lifespan and optimizing its performance.
  • Electrostatic charge: Some HEPA filters are electrostatically charged, which improves their ability to attract air particles, particularly capturing nanoparticles.

Levels of Filtration: MERV vs. HEPA Standards

While HEPA is the gold standard for air purifiers, not all filters meet this criteria. The MERV (Minimum Efficiency Reporting Value) scale grades filters based on their ability to capture particles between 0.3 and 10 microns. MERV ratings range from 1 to 16, with higher numbers indicating better filtration. HEPA filtration equates to MERV 17-20.

Keeping Top Performance

True HEPA filters have impressive efficiency, capturing nanoparticles as small as 0.3 microns in size. However, these filters are actually most effective at trapping particles that are either larger or smaller than 0.3 microns. Larger particles are more easily trapped through inertial impaction and interception, while smaller particles are more likely to be caught through diffusion.

Uses and Applications of HEPA Filters

HEPA systems are widely used due to their versatility and effectiveness in trapping airborne particles and producing clean air. From homes to commercial office buildings and medical facilities, HEPA air purifiers are crucial to mitigate disease transmission and improve indoor air quality. Let’s explore some of the most common uses and applications of HEPA filters.

  • HEPA Filters in Homes:
    • Many home appliances, such as vacuum cleaners, air purifiers, and hair dryers, use HEPA filters to trap dust, allergens, and other particles.
    • This can be particularly beneficial for those with allergies, asthma, or other respiratory sensitivities who use these products daily.
  • Commercial Office Buildings, Retail Spaces, and Industrial Use:
    • In commercial and industrial environments, HEPA systems protect workers by providing a clean working environment.
    • They are commonly implemented in manufacturing facilities, retail spaces, clean rooms, and laboratories to control airborne particles.
  • Use of HEPA Filters in Medical Facilities:
    • In healthcare settings, HEPA filters control infection and mitigate disease transmission.
    • They are used in isolation rooms, operating theaters, and pharmaceutical processing areas to capture airborne microorganisms that could be potentially harmful.

Buying and Maintaining a HEPA Filter

Investing in a HEPA filter is important for maintaining clean and healthy air in your home or workspace. To choose the right filter and keep it functioning optimally, consider these key factors and follow proper maintenance guidelines.

  • Size: Confirm the filter is appropriate for the space and the ventilation system. 
  • CADR rating: The Clean Air Delivery Rate indicates how quickly the filter can clean air in a given room size.
  • Noise level: Some filters can be loud, so consider the noise level if the filter will be used in a bedroom or quiet space.
  • Cleaning: HEPA filters should be cleaned regularly according to the manufacturer’s instructions to maintain optimal performance. Vacuuming the exterior of the filter to remove accumulated dust.
  • Replacement: Most filters should be replaced every 12-18 months. Some may need to be replaced more frequently if used in an environment with heavy air pollution. A drop in airflow or an increase in operating noise can indicate that a filter needs to be replaced.

Additional Real-World Considerations

While these filters are effective indoor air quality solutions, it is important not to look over potential side effects and the environmental impact of their use. This section explores the health benefits of HEPA systems, addresses common concerns about their safety, and stresses the importance of proper disposal and recycling.

  • Health benefits: The use of a HEPA air purifier can have significant health benefits, especially for those with sensitivity to poor air quality. By trapping airborne irritants and allergens, filters can alleviate systems and improve indoor living and working conditions.
  • Side Effects: While some have raised concerns about potential side effects of HEPA air filtration, such as the generation of ozone, studies show that properly designed and maintained filters do not produce harmful ozone levels.
  • Recycling and Sustainability: When a HEPA filter reaches the end of its lifespan, dispose of it properly. Many HEPA filters can be recycled, and some manufacturers offer take-back programs. Check with your local recycling facility or the filter manufacturer for guidance.

HEPA filters are a powerful tool in pursuing clean, healthy air. By understanding how they work, their various applications, and proper maintenance, anyone can harness the power of HEPA filtration to create safer, more comfortable environments in homes, workplaces, and beyond.

The Logan Difference

At Logan A/C & Heat, we’re more than just your average HVAC company. As a family-owned and operated business, we go above and beyond to guarantee that every interaction with our team is positive and that every installation is completed to the highest standards.

Our commitment to quality starts with our rigorous training program. Every installer on our team undergoes extensive training to ensure they have the skills and knowledge to complete installations effectively. We also confirm our installers have all the necessary parts and equipment before heading out to a job site, minimizing customer delays and frustration.

Our job isn’t finished until our customers are completely satisfied. That’s why we take the time to do a walkthrough with each customer after the installation is complete to show them how to set up their new system and answer any questions they may have.

When you choose Logan A/C & Heat, you’re not just choosing an HVAC company – you’re choosing a partner who is dedicated to your comfort, satisfaction, and peace of mind. That’s the Logan Difference.

Frequently Asked Questions

Can HEPA filters capture viruses?

Yes, HEPA filters can capture airborne virus particles. True HEPA filters are certified to capture particles down to 0.3 microns in size, including many virus particles. While HEPA filters can help reduce the risk of viral transmission, they are not a substitute for other preventive measures and require maintenance to continue working properly.

How often should I replace my HEPA filter?

Always refer to the manufacturer’s recommendations for specific guidance on filter replacement. When you notice a decrease in airflow or an increase it noise, it may be time to replace your filter. A good rule of thumb is every 12-18 months, but this number can be influenced by the size of the space, level of pollution, and frequency of use.

Are HEPA filters safe?

Yes, HEPA filters are considered safe. They do not use harmful chemicals or produce high levels of ozone, a common concern with some ventilation systems. Choose a reputable brand and follow the manufacturer’s instructions for use and maintenance. If you have specific health concerns, consult with your healthcare provider before using a new air filtration product.

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