HEPA filters - precision technology for clean air and the highest standards
1. Why clean air counts: The importance of HEPA filters
Clean air is a decisive factor, whether in research or in the production of sensitive components, where the highest standards of purity are essential. In these areas, even tiny contaminants in the air can affect the quality of products or the accuracy of experiments. In particular, clean rooms that are protected by HEPA filter technology offer the necessary air quality to carry out sensitive processes without the risk of contamination by dust or other particles. The research and development of new technologies in photonics or microelectronics requires precise control of environmental conditions. In these sensitive areas, HEPA filters are essential to remove particles that could interfere with the production of semiconductors or optical components.【1】【3】This not only protects people's health, but also the quality of high-tech products and research results.
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2. The science behind HEPA filters
HEPA filters rely on four primary mechanisms to purify air:
- Inertial deposition: Larger particles are directly suspended from the fibers of the filter due to the inertia of the air flow.
- Direct interception: Particles that are large enough are captured through direct contact with the filter fibers.
- Brownian diffusion: Very small particles move randomly and collide with the fibers so often that they are finally captured.
- Electrostatic forces: Tiny, charged particles are trapped by the gravitational pull of the filter fibers.【2】
The 0.3 µm particles represent the biggest challenge — this size is considered the “most difficult to filter” (MPPS). This is because these particles are too large to completely diffuse through the filter, but also small enough not to immediately stick to the fibers. This is the reason why HEPA filters, which can effectively filter this particle size in particular, are considered particularly efficient.
3. Overview of HEPA and ULPA classes
HEPA and ULPA filters are divided into different classes, which describe their filtration performance. HEPA filters range from H10 to H14, while ULPA (Ultra Low Penetration Air) filters include even more stringent classes 15 and 16. These filters are crucial for achieving the highest cleanliness standards in clean rooms. An overview of filter classes and their performance:
- H10: filtration rate of 85%
fact: H10 filters are often used in simple air purifiers and are suitable for applications with moderate air purity requirements. - H11: filtration rate of 95%
fact: H11 filters remove a lot of pollen, dust and coarse particles and are used in building and vehicle ventilation. - H12: filtration rate of 99.5%
fact: This filter class offers good protection against particulate matter and allergens, making it ideal for more demanding air purification tasks. - H13 : filtration rate of 99.95%
fact: H13 filters are often used in ISO Class 7 clean rooms and guarantee a significant reduction of particles in the air. - H14 (e.g. used in Nordair systems): filtration rate of 99.995%
fact: H14 filters can remove up to 99.995% of all particles ≥0.3 µm and are used in ISO Class 5 and higher clean rooms, which is critical for microelectronics and photonics. - ULPA 15: Filtration rate of 99.9995%
fact: This filter class is used in ISO Class 4 clean rooms, where even the lowest particle concentration could cause damage, such as in semiconductor manufacturing. - ULPA 16: Filtration rate of 99.99995%
fact: ULPA-16 filters are the most powerful filters and are used in clean rooms where particle contamination must be absolutely minimized, such as in research institutions with highly sensitive processes.
4. What HEPA filters do — and what they don't
HEPA filters are extremely efficient at removing particles from the air, but they have their limits. They cannot filter volatile organic compounds (VOCs) or gases such as ozone because these molecules are too small to be captured by the filter's fibers. This is particularly important in environments such as operating rooms or pharmaceutical laboratories, where in addition to particle removal, the elimination of germs and gases also plays a role.【4】【3】【5】
5. Nordair Systems: Why we rely on HEPA-H14
At Nordair Systems, we primarily use HEPA H14 filters, as they offer a filtration rate of 99.995% and therefore meet the highest purity requirements. Higher filtration rates, such as those of the ULPA 15 filters, offer even higher purity, but also mean higher power consumption due to pressure loss. At Nordair Systems, we see HEPA 14 filters as the perfect combination of effectiveness and energy efficiency for our customers.
The flexibility and benefits of HEPA H14 filters are complex: they not only offer extremely high filtration performance, but also high reliability and durability, making them ideal for continuous use in the most demanding environments. Thanks to their high efficiency and compliance with international standards such as ISO 14644-1 and EN 1822, our customers can be sure that their cleanrooms meet the highest standards.
Source references:
- ISO 14644-1: Cleanrooms and associated controlled environments — Part 1: Classification of air cleanliness by particle concentration.
- ISO 14644-4: Cleanrooms and associated controlled environments — Part 4: Design, construction, and start-up.
- Perry, J., Agui, J., & Vijayakumar, R. (2016). Removal of submicron and nanoparticle contaminants by HEPA-rated media filters and packed beds of granular materials. Journal of Aerosol Science.
- Dubey, S., Rohra, H., & Taneja, A. (2021). Evaluation of the effectiveness of air purifiers (HEPA) in controlling particle pollution indoors. Heliyon, 7(9), e02079.
- Sanalife (2022). True HEPA vs. HEPA filters: What's the difference?
