The core filtration efficiency of the ultra-low resistance medium and high efficiency filter unit corresponds to the medium and high efficiency grade of the air filter (usually referring to F7 to F9 grades in the industry, and some products can cover the H10 entry-level high efficiency grade). The specific efficiency values are classified according to international standards (such as EN 779, ASHRAE 52.2). The following are the clear indicators:
1. Core grades and Efficiency Range (in accordance with EN 779 standard)
F7 grade: For particles with a diameter of ≥1.0μm, the filtration efficiency is 80% to 90% (the gravimetric method efficiency is ≥65%).
F8 level: For particles with a diameter of ≥1.0μm, the filtration efficiency is 90% to 95% (the efficiency of the gravimetric method is ≥80%).
F9 grade: For particles with a diameter of ≥1.0μm, the filtration efficiency is 95% to 99% (the gravimetric method efficiency is ≥90%).
Some high-end ultra-low resistance products can reach H10 level (EN 1822 standard) : for particles with a diameter of ≥0.3μm, the filtration efficiency is ≥95% (sodium flame method), still maintaining low resistance characteristics (initial resistance ≤120Pa).
2. Test Standard Description
Efficiency tests typically employ manual dust weighing method (for evaluating coarse particle filtration capacity), atmospheric dust colorimetric method (for evaluating fine particle filtration capacity), or DOP/PAO oil mist method (for H10 and above grades, testing particle size of 0.3μm).
“Ultra-low resistance” is a characteristic relative to traditional medium and high-efficiency filters (the initial resistance of traditional F7 is about 150Pa, while ultra-low resistance products can be as low as 80 to 120Pa). The efficiency grade and resistance optimization do not conflict, and the core is achieved through the design of filter material structure (such as gradient density non-woven fabric, low-resistance coating technology).
3. Efficiency performance in practical applications
For PM2.5 in the air (particle size ≤2.5μm), the actual filtration efficiency of F8/F9 grade products can reach 85% to 95%.
For pollen and mold spores (particle size ≥5μm), the efficiency is close to 100%. For bacterial aerosols (particle size 0.5-5μm), the efficiency is ≥90% (F8 and above).