Archive: October 29, 2021

The filtration efficiency of an air filter is simply the ratio of the amount of dust captured to the original air dust content. The meaning of efficiency seems simple, but its value will be very different from the test method. When the dust concentration in the filtered gas is expressed by the weight concentration, the efficiency is the weight efficiency; when the count concentration is expressed, the efficiency is the efficiency efficiency; when other physical quantities are used as relative expressions, it is the colorimetric efficiency or Turbidity efficiency, etc.

Historically, one group engaged in HVAC and clean room purification, and another group engaged in car filters. Those engaged in dust collectors and those engaged in liquid filtration used their own methods and said their respective efficiencies. When air filter factories are mixed with the sale of automobile filters, or when dust collectors develop air filters, they will inevitably be confused by what they call filtration efficiency. In this chaotic situation, if you must know the specific efficiency value, please don’t forget to specify the specific test method and the method of calculating the efficiency. Below, please see my painstaking dry goods summary. I hope you can have a better understanding of filtration efficiency. Whether it is purchasing air filtration equipment, purification products, or choosing air purifiers in industrial clean rooms, you have your own opinions and choices. . Will not be fooled by Internet promotion and business advertisements following the trend.

The most commonly used method of expression is the counting efficiency expressed by the concentration of dust particles in the airflow at the inlet and outlet of the filter.

    1. Under the rated air volume, according to the national standard GB/T14295-93 “Air Filter” and GB13554-92 “High Efficiency Air Filter”, the efficiency ranges of different filters are as follows:

    Primary effect filter, for particles ≥5 microns, filtration efficiency 80＞E≥20, initial resistance ≤50Pa

    Medium-efficiency filter, for ≥1 micron particles, filtration efficiency 70＞E≥20, initial resistance ≤80Pa

    High and medium efficiency filter, for ≥1 micron particles, filtration efficiency 99＞E≥70, initial resistance ≤100Pa

    Sub-high efficiency filter, for ≥0.5 micron particles, filtration efficiency E≥95, initial resistance ≤120Pa

    High efficiency filter, for ≥0.5 micron particles, filtration efficiency E≥99.99, initial resistance ≤220Pa

    Ultra-high efficiency filter, for ≥0.1 micron particles, filtration efficiency E≥99.999, initial resistance ≤280Pa

    2. Since many companies now choose imported filters, and their methods of expressing efficiency are different from those in China, for ease of comparison, the conversion relationship between them is listed as follows:

    According to European standards, coarse-efficiency filters are divided into four levels (G1~~G4):

    G1 efficiency to particle size ≥5.0μm, filtration efficiency E≥20% (corresponding to American standard C1)

    G2 efficiency to particle size ≥5.0μm, filtration efficiency 50＞E≥20% (corresponding to American standards C2~C4)

    G3 efficiency to particle size ≥5.0μm, filtration efficiency 70＞E≥50% (corresponding to American standard L5)

    G4 efficiency to particle size ≥5.0μm, filtration efficiency 90＞E≥70% (corresponding to American standard L6)

    The medium-efficiency filter is divided into two levels (F5~~F6):

    F5 efficiency to particle size ≥1.0μm, filtration efficiency 50＞E≥30% (corresponding to American standards M9, M10)

    F6 efficiency to particle size ≥1.0μm, filtration efficiency 80＞E≥50% (corresponding to American standards M11, M12)

    High and medium efficiency filters are divided into three levels (F7~~F9):

    F7 efficiency to particle size ≥1.0μm, filtration efficiency 99＞E≥70% (corresponding to American standard H13)

    F8 efficiency to particle size ≥0.5μm, filtration efficiency 90＞E≥75% (corresponding to American standard H14)

    F9 efficiency to particle size ≥0.5μm, filtration efficiency 99＞E≥90% (corresponding to American standard H15)

    The sub-high efficiency filter is divided into two levels (H10, H11):

    H10 efficiency to particle size ≥0.5μm, filtration efficiency 99＞E≥95% (corresponding to American standard H15)

    H11 efficiency to particle size ≥0.5μm, SEO, filtration efficiency 99.9＞E≥99% (corresponding to American standard H16)

    The high efficiency filter is divided into two levels (H12, H13):

    H12 efficiency to particle size ≥0.5μm, filtration efficiency E≥99.9 % (corresponding to American standard H16)

    H13 efficiency to particle size ≥0.5μm, filtration efficiency E≥99.99% (corresponding to American standard H17)