Types of HEPA Filters: Selection and Applications

High-efficiency particulate air (HEPA) filtration plays a key role anywhere air quality and contamination control are among your top priorities. Choosing the right HEPA filter types directly impacts performance in high-stakes settings such as cleanrooms, laboratories, and pharmaceutical applications. 

Not all types of HEPA filters are built for the same job. There are many different options, which can make it challenging to identify the right solution for your intended application. Common options include:

• Standard HEPA filters

• Fan-powered HEPA filter units (FFUs)

• Low-profile HEPA filters

• Terminal diffuser HEPA models

• ULPA filters 

This guide explores types of HEPA filters, as well as common applications, such as in cleanroom HVAC systems. You’ll learn how to select the appropriate filtration option for your use case to promote energy efficiency and air quality control. 

What Is a HEPA Filter?

If you work in clean air environments, you already know the basics, but a quick refresher helps set the stage before diving into specific filtration limits. HEPA filters have the ability to remove at least 99.97% of particles at 0.3 microns. They capture airborne contaminants like dust, pollen, mold spores, and bacteria. 

Compared to conventional HVAC filters, HEPA filtration offers:

• Much higher particle removal efficiency

• Consistent performance in a controlled environment

• Compliance with cleanroom and industry standards 

HEPA filters are superior to conventional filtration options. However, it’s vital to choose the right HEPA filter types to effectively protect your workspace from airborne contaminants. 

Main Types of HEPA Filters

All HEPA filters meet the 99.97% filtration rate when dealing with particles at 0.3 microns. However, they are available in different formats to support your airflow, space, and application needs. Several types are used most often.

Standard HEPA Filters

Standard HEPA filters are defined by their 99.97% efficiency at 0.3 microns. They are typically installed within housings or air handlers to provide reliable particulate control. Common applications include:

• Cleanrooms

• Laboratories

• Medical and pharm spaces

• Industrial process areas

These filters are often selected when space allows for traditional housings and when airflow is supplied by a centralized system. 

Fan Powered HEPA Filter Units

FFUs integrate a HEPA filter with an onboard fan. FFU filter accessories are a valuable addition when you need self-contained airflow and scalable modular installation. The units can be mounted in ceilings and are widely used in modular cleanroom designs. 

FFUs are especially useful if your facility requires flexibility. For example, you would likely use FFUs in a modular cleanroom. 

Low-Profile HEPA Filters

Low-profile HEPA filters are designed for installations where you have limited vertical clearance. They provide the same filtration efficiency as standard HEPA filters but in a thinner form. Investing in low-profile options is more cost-effective than making structural modifications to accommodate a regularly sized filter. 

Terminal Diffuser HEPA Modules

These systems combine air distribution and final filtration in a single ceiling-mounted unit. They are installed at the point of air delivery to provide clean, controlled airflow into the space. 

Common environments include ISO-classified cleanrooms, healthcare facilities, and semiconductor manufacturing. Terminal modules help maintain consistent airflow patterns while simplifying system design and maintenance. 

Enhanced EEF HEPA Filtration Systems

Enhanced energy-efficient filtration systems reduce drops in pressure while maintaining high filtration performance. Benefits include:

• Reduced fan energy demand

• Lower operational costs

• Improved system longevity

While EEF setups are more costly up front, you can enjoy long-term savings. 

ULPA Filters 

Ultra-low penetration air (ULPA) filters exceed HEPA standards. Typically, they remove 99.9995% of particles at 0.12 microns. While they are not required for most applications, you may need ULPA filters when extreme particulate control is necessary. Common examples include:

• Semiconductor manufacturing

• Advanced research environments

• Specialized pharmaceutical processes

Due to the cost of ULPA filters, they are only used when absolutely necessary. 

HEPA Filter Classifications & Ratings

To be considered a HEPA filter, the filtration device must capture at least 99.97% of particulates at 0.3 microns. However, there are several classes of HEPA filters, which range from H10 to H14. The higher the number, the more efficient the filter.

HEPA filter classes are outlined in ISO 29463, which replaced the previous EN 1822 European standard. H10 to H12 filters are sometimes called “True HEPA” because they meet the minimum standard for particulate capture. 

H13 and H14 filters are sometimes referred to as “medical grade.” H13 filters capture 99.95% of particles down to 0.3 microns, and H14 filters capture 99.995% of particles down to 0.3 microns. 

Selection Considerations & Common Mistakes

When selecting from different HEPA filter types, consider the following:

• What your application is (i.e., cleanrooms, process sensitivity)

• Whether you want to mitigate pressure drops

• Compatibility with your existing systems

• Filter replacement and service intervals

You should also avoid these common mistakes:

• Focusing on efficiency rating while neglecting the energy impact of your selection

• Ignoring pressure drop during system design

• Improper installation that compromises filter seals

• Delaying routine maintenance, which could negatively impact your workspace 

Make sure your team is trained on HEPA filter maintenance and installation. Create a filter replacement schedule in accordance with industry standards and the manufacturer’s recommendations. 

You should also periodically check the air quality in your workspace to verify that the filters are capturing particulates and preventing contamination. 

Choosing the Right HEPA Filter Types 

The high-efficiency particulate air filters you install in your workspace will either set you up for success or open the door for costly contamination. Each filter configuration serves a specific purpose within your controlled environment. 

Selecting the right HEPA filter type will support long-term performance, energy efficiency, and compliance with cleanroom standards.

If you need assistance selecting HEPA filters or are preparing for a new cleanroom system design, CleanAir Solutions is here to help. Our experts will gather information about your intended use cases and provide filter selection guidance.

Contact CleanAir Solutions for expert assistance from one of our dedicated team members.