HEPA and ULPA filters are air filters designed to trap a large majority of very small contaminant particles from a current of air. On average, it is recommended that these types of filters be replaced every 3 to 6 months, depending on the use and type of filter. Ultra-low particulate air (ULPA) filters are 99.999% efficient at removing submicron particles 0.12 microns in diameter or greater, while HEPA filters are 99.97% efficient at removing particles 0.3 microns in diameter or greater. Most current HEPA filters, especially those used in portable air purifiers, also have a pre-filter to capture larger debris and an activated carbon filter to eliminate odors. Based on these data, the life expectancy of a HEPA or ULPA filter in an enclosure with self-adjusting motor technology would likely be well over 10 years.
When performing an accurate filter leak test, the aerosol concentration should be uniform across the upstream face of the filter or filters being tested. Air filtration experts have found that the additional thickness of ULPA filters reduces airflow by 20-50%.When leak testing is performed at the joints between the filter frame and the housing, the probe is inserted into that area and then the area is scanned to determine local collection efficiencies of S. It is recommended to repeat the test at regular time intervals to verify the continuous efficiency of the filter. During the test, the filter is subjected to an aerosol probe, which means that it is challenged by the introduction of particles into the air and the output is measured. The ULPA filter's higher efficiency rating is due to the higher density of the filter media, which allows up to 50% lower airflow than HEPA filters and requires more power to move air.
Determining the best filter for your application requires careful analysis of your needs and the containment standards of your installation, including the minimum number of air changes required per hour. On average, it is recommended that HEPA and ULPA filters be replaced every 3 to 6 months depending on their use and type. With self-adjusting motor technology, their life expectancy can be well over 10 years. When performing a filter leak test, aerosol concentration should be uniform across its upstream face. ULPA filters reduce airflow by 20-50% compared to HEPA filters due to their higher density media. It is important to repeat tests at regular intervals to verify their continuous efficiency.
The best filter for any application depends on careful analysis of needs and containment standards, including minimum number of air changes per hour. With proper maintenance and care, HEPA and ULPA filters can last for many years.