Air filter materials are used to filter suspended particles in the air. It plays an important role in daily production and life, and is the core component of the filtering device. It plays an important role in improving indoor air quality. Therefore, good filter materials can provide a healthy living and working environment for people.
There are many kinds of air filtration, which can be divided into particle air filtration materials, foam air filtration materials, microporous membrane air filtration materials and nonwoven fiber air filtration materials according to their appearance. Regardless of the type of filter material, the basic filtration performance evaluation indexes mainly include filtration efficiency, resistance pressure drop (piezoresistance), quality factor and dust capacity.
There are five main methods to test the filtration efficiency, including sodium flame method, oil mist method, colorimetric method, atmospheric dust gravimetric method and counting method. According to the filtration efficiency, the air filter fabric material can be further classified, so as to more intuitively define the efficiency and use occasions of the materials. The resistance pressure drop is the gas pressure difference between the upstream and downstream of the filter material. Because the continuous dust holding of the filter material will affect the gas flow during its use, the pressure resistance of the filter material should not only test its initial value, but also monitor its changes during its long-term use. In general, with the filtration process, the pressure resistance of the material will become larger and larger, and the energy consumption of the filter material in the service process will also increase. According to the national standard GBT 14295-2008, when the resistance value increases to twice the initial resistance value, the service of the filter material is deemed to have ended. Quality Factor (QF) is a performance index that comprehensively considers the filtration efficiency and resistance pressure drop. It is usually used as a balance index of filtration performance. Therefore, the higher the quality factor of materials, the better their filtration performance. The dust holding capacity refers to the total amount of particles contained by the filter material during service. The higher the dust holding capacity is, the longer the service life is.
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