Learn about the benefits, the structure, the standards, and the maintenance of HEPA filters, a type of filter that can remove very small particles from the air.

While HEPA filters are certified to capture 99.97% of all particles down to 0.3 microns, their efficiency is far greater than that! As the filter becomes clogged with debris, the filtration capacity will increase, however, it will also begin to restrict airflow. Also, the electrostatic effect of the filter material will collect materials far smaller. In fact, NIOSH studies have shown that the hardest particles to collect were those around 0.3 microns, with efficiency increasing with both larger and smaller particles. Keep in mind that these efficiencies can only be seen if the housing of the filter is effectively sealed against the supporting surface.

What is HEPA filtration and how does it work?

If you work in environmental services, you may have heard of HEPA filtration, but do you know what it is and how it works? HEPA stands for high-efficiency particulate air, and it is a type of filter that can capture very small particles from the air. HEPA filters are used in many applications, such as hospitals, clean rooms, laboratories, and air purifiers, to reduce the risk of airborne contamination and infection. In this article, you will learn about the benefits, the structure, the standards, and the maintenance of HEPA filters.

1 Benefits of HEPA filtration

HEPA filters can remove up to 99.97% of particles that are 0.3 microns or larger from the air. This means that they can trap dust, pollen, mold, bacteria, viruses, and other allergens and pathogens that can cause health problems. HEPA filters can improve the indoor air quality and the hygiene of the environment, especially in settings where people are vulnerable to infections or have respiratory issues. HEPA filters can also protect the equipment and the products from being damaged or contaminated by airborne particles.

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Muhammad Ejaz

Macroeconomics, Bank Supervision
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HEPA is a type of air filter that traps particles such as dust, pollen, pet dander, and other airborne pollutants. HEPA filters are composed of a mat of randomly arranged fibers, typically fiberglass. These fibers are designed to capture particles as air flows through the filter. HEPA filters work through a combination of three mechanisms: Interception: Particles in the air stream come into contact with the fibers and adhere to them as the air flows through the filter. Impaction: Larger particles cannot follow the air stream's curving path and collide with the fibers, becoming trapped. Diffusion: Very small particles are bombarded by air molecules, causing them to deviate from the airflow and collide with the filter fibers.

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2 Structure of HEPA filters

HEPA filters are made of a dense mat of randomly arranged fibers, usually made of glass or synthetic materials. The fibers have a diameter of 0.5 to 2 microns, and the spaces between them are smaller than the particles they capture. The particles are trapped by three mechanisms: interception, impaction, and diffusion. Interception occurs when the particles touch the fibers and stick to them. Impaction occurs when the particles are too large to follow the air stream and collide with the fibers. Diffusion occurs when the particles are very small and move randomly due to collisions with air molecules, increasing their chances of hitting the fibers.

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3 Standards of HEPA filters

HEPA filters are classified according to their efficiency and their resistance to airflow. The efficiency is measured by the percentage of particles that are captured by the filter at a certain size. The resistance is measured by the pressure drop across the filter at a certain airflow rate. The higher the efficiency and the resistance, the more effective and the more expensive the filter. There are different standards for HEPA filters in different regions and industries, such as the European EN 1822, the American ASME AG-1, and the ISO 29463. These standards specify the minimum requirements for the performance and the testing of HEPA filters.

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4 Maintenance of HEPA filters

HEPA filters require regular maintenance to ensure their optimal function and lifespan. The maintenance includes inspecting, cleaning, replacing, and disposing of the filters. Inspecting the filters involves checking for any damage, leaks, or clogs that can affect the airflow and the efficiency. Cleaning the filters involves removing any dust or debris that accumulates on the surface or in the gaps of the fibers. Replacing the filters involves installing new filters when the old ones are worn out or contaminated beyond repair. Disposing of the filters involves sealing and labeling them properly and following the safety and environmental regulations for hazardous waste.

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5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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Jack G.

Vice President Environment Health Safety at ALC Environmental
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While HEPA filters are certified to capture 99.97% of all particles down to 0.3 microns, their efficiency is far greater than that! As the filter becomes clogged with debris, the filtration capacity will increase, however, it will also begin to restrict airflow. Also, the electrostatic effect of the filter material will collect materials far smaller. In fact, NIOSH studies have shown that the hardest particles to collect were those around 0.3 microns, with efficiency increasing with both larger and smaller particles. Keep in mind that these efficiencies can only be seen if the housing of the filter is effectively sealed against the supporting surface.

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Jesús López Redondo

Responsable Técnico Legionella en Rentokil Initial 🦠 | Responsable Centro de Excelencia de Legionella 💧| National Legionella Quality Assurance 💯
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In the article I miss the reference to indoor air quality (IAQ) analysis. This study is necessary to assess the condition of HEPA filters, as well as other types of factors that influence indoor air quality in buildings. Air quality is important in the buildings where we work, we spend many hours a year in buildings and poor air quality can affect workers' tiredness, headaches, stress, respiratory problems, allergies...

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What is HEPA filtration and how does it work?

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4

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1 Benefits of HEPA filtration

2 Structure of HEPA filters

3 Standards of HEPA filters

4 Maintenance of HEPA filters

5 Here’s what else to consider

Environmental Services

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What is HEPA filtration and how does it work?

1

2

3

4

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1 Benefits of HEPA filtration

2 Structure of HEPA filters

3 Standards of HEPA filters

4 Maintenance of HEPA filters

5 Here’s what else to consider

Environmental Services

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