Several Main Filtration Properties Of Filter Media

Filtration efficiency, filtration resistance and dust capacity are three important parameters to evaluate the filtration performance of Air Filter Media. Filtration efficiency is the primary basis for the classification of Filter Fabric Non Woven products, which determines whether the air can meet the purification requirements; filtration resistance and dust capacity are important indicators to distinguish Filter Cloth product quality. The lower the filtration resistance, the smaller the intake load during air filtration and the lower the operating cost; if the dust holding capacity of the filter material is high, the service life of the filter is generally higher.

Filtration efficiency refers to the percentage of particles captured by a filter material under specified test conditions. By substituting the mass or quantity of particulate pollutants, the weight counting efficiency and counting efficiency of the filter material are obtained, respectively. For the same filtration process, the values of count efficiency and weight efficiency can sometimes vary greatly. When actually comparing filter efficiency values, we need to compare the efficiency to the same definition. At present, the counting efficiency is used in the theoretical research of fiber air filtration. However, in its application and testing, the filter material adopts the counting efficiency, the coarse filter material adopts the weight counting efficiency, and the medium efficiency filter material needs to comprehensively consider the weight efficiency and the weight efficiency.

The dust holding capacity refers to the total mass of particulate pollutants that can be captured by the filter material when the specified end pressure difference is reached in the test, and the unit is G. Generally speaking, the dust holding capacity affects the service life of the filter material. However, since the dust capacity is related to the particle size and distribution of the aerosol particles, the aerosols used in any experiment cannot fully represent the air conditions in the actual use environment of the filter material, so the experimental value of the dust capacity will be different from the actual value.

Filtration resistance refers to the pressure drop of aerosol passing through the surface of the inlet and outlet of the test filter material under specified conditions, and the unit is PA or mmh2o. The filtration resistance has a certain corresponding relationship with the permeability of the filter material. The smaller the air permeability, the greater the filtration resistance. Filtration resistance reflects the degree of energy loss caused by the filter material during filtration. For filter materials with the same filtration efficiency, the lower the filtration resistance, the smaller the load of the purification system, the lower the operating cost, and the longer the service life of the filter. For clean filter media, the filtration resistance depends only on the characteristics of the filter media and fluid. However, as the filtration process progresses, the structure and pores of the filter material will change, and the particles deposited inside or on the surface of the filter material will greatly affect the filtration resistance. Generally speaking, as the filtration process proceeds, the filtration resistance gradually increases until the end pressure difference is reached. And the filter material reaches its service life, thereby terminating the test or replacing the filter.

As a pair of contradictions, the competition between filtration efficiency and filtration resistance affects the quality factor of the filter material. The higher the filtration efficiency or the lower the filtration resistance, the greater the quality factor; the lower the efficiency or the greater the resistance, the smaller the quality factor. In terms of filtration efficiency and filtration resistance, the larger the quality factor, the better the filtration performance. Therefore, an improvement in filtration performance is also an improvement in the quality factor value.