Choosing between HEPA and ULPA filters affects airflow, energy use, and contamination control. A higher efficiency grade is not automatically the better option: ULPA may add unnecessary resistance where HEPA performance is sufficient, while an underspecified filter can put particle-sensitive processes at risk.
This guide compares MPPS efficiency, pressure drop, applications, and specification requirements under EN 1822 and ISO 29463. Buyers evaluating available HEPA and ULPA filter options can use these criteria to match filter performance with their system capacity and operating requirements.
What Is the Difference Between HEPA and ULPA Filters?
Filtration Efficiency and Particle Size
HEPA and ULPA filters differ primarily in their permitted particle penetration. Under the common U.S. definition, a HEPA filter captures at least 99.97% of 0.3 µm particles. Under EN 1822, filters are classified by efficiency at their measured Most Penetrating Particle Size (MPPS): H13 and H14 are HEPA grades, while U15 through U17 are ULPA grades. ULPA filters allow substantially fewer particles to penetrate, but their higher efficiency can also increase airflow resistance.
Airflow Resistance and Energy Use
Replacing a HEPA filter with a ULPA filter in the same system may reduce airflow if the fan cannot overcome the additional resistance. The actual effect depends on filter dimensions, media area, construction, and rated airflow.
