What is a HEPA Air Filter?

A HEPA (High-Efficiency Particulate Air) filter is a type of air filter that is designed to trap a large amount of very small particulate contaminants. These filters are highly effective at capturing particles of various sizes, making them a key component in many air purification systems

1.
Efficiency

HEPA filters must meet specific standards of efficiency. For instance, a true HEPA filter must capture at least 99.97% of particles that are 0.3 microns in diameter.
The size of 0.3 microns is known as the most penetrating particle size (MPPS), meaning that particles of this size are the most difficult to capture. The filter's ability to capture these particles ensures it is effective for both smaller and larger particles.


2.
Construction

HEPA filters are typically made from a mat of randomly arranged fibers, usually composed of fiberglass.
The fibers are arranged in a way that creates a dense network, which captures particles through several mechanisms: interception, impaction, and diffusion.





3.
Mechanisms of Action

  • Interception: Particles following a streamline in the air flow come within one radius of a fiber and adhere to it.
  • Impaction: Larger particles cannot avoid fibers by following the streamline and are forced to embed in one of them directly.
  • Diffusion: Very small particles move erratically (Brownian motion) and are more likely to collide with fibers.

4.
Health Improvements

  • Allergy Relief: HEPA filters can trap common allergens, providing relief for allergy sufferers.
  • Asthma Control: Removing airborne triggers helps manage asthma symptoms.
  • Reduced Illness: Filtering out bacteria and viruses can decrease the likelihood of respiratory infections.

5.
HEPA Filter Efficiency Ratings

H10-H12:

  • Efficiency: Captures 85% to 99.5% of particles 0.1 microns and larger.
  • Usage: Generally used in residential air purifiers and HVAC systems.

H13-H14:

  • Efficiency: H13 filters capture 99.95% and H14 filters capture 99.995% of particles 0.1 microns and larger.
  • Usage: Used in medical facilities, cleanrooms, and high-efficiency air purifiers.

>U15-U17 (ULPA Filters):
  • Efficiency: Captures 99.9995% to 99.9999% of particles 0.12 microns and larger.
  • Usage: Used in environments requiring the highest levels of air purity, such as pharmaceutical manufacturing and semiconductor fabrication.

6.
Conclusion

HEPA filters and HEPA air cleaners are vital tools for improving indoor air quality. By effectively capturing a wide range of airborne particles, they help create healthier living and working environments, reducing exposure to allergens, pollutants, and pathogens. Whether for residential or commercial use, these devices play a crucial role in maintaining clean air standards.