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What factors affect the filtration efficiency of air filters?
What factors affect the filtration efficiency of air filters?The filtration efficiency of air filters not only directly affects the living environment, but also has a certain impact on the production environment and work efficiency. Therefore, the filtration efficiency of air filters is the key data to pay attention to when purchasing air filters. Since filtration efficiency is so important, what are the factors that affect the filtration efficiency of air filters?1. Filter bag material: The selection and application of filter bag materials and the core technology of bag dust collection equipment play a decisive role in the performance of high-efficiency air filter dust collectors. Due to the environment of each dust collection point, the nature, temperature, and technical requirements of dust processing are different. Different filter materials must be selected according to different conditions and corresponding technical protection measures must be taken. The requirements for filter bag materials include the following technical properties: filter bag materials are suitable for different temperatures, have good peelability, are easy to clean, have good air permeability, low resistance, high filtration efficiency, high density, can withstand high-intensity cleaning, and have a service life Long and affordable. 2. Influence of filtration wind speed: As the wind speed increases, the resistance increases, and as the wind speed decreases, the resistance decreases. For large particles that mainly move by inertia, the wind speed increases, the inertia of the particles increases, and the possibility of wiping obstacles increases, so the filtration efficiency increases. However, as the inertia increases, the rebound force of the obstacle against the particles also increases. If the van der Waals force cannot overcome the rebound force, the particles will run away. Therefore, sometimes when the wind speed is increased, the filtration efficiency of the filter for large particles will decrease. For small particles that mainly move by diffusion, the filtration efficiency depends on the residence time of the particles in the filter medium. If the residence time is shortened (the wind speed is increased), the probability of the particles hitting obstacles is reduced, and the filtration efficiency is lower. If the material is electrostatically charged, the filtration efficiency depends on the residence time of the e-air flow in the material. The lower the filtration wind speed, the higher the filtration efficiency, which is true for both large and small particles. Electrostatically charged materials are very sensitive to filter wind speed. For example, when measured at a wind speed of 1 cm/s, the transmittance of 0.3 μm dust is 0.01% (filtration efficiency 99.99%). When the filtration wind speed is increased to 5.3 cm/s, the measured transmittance is 1.5% (filtration efficiency). Only 98.5%), a difference of two orders of magnitude. 3. Effect of humidity: Generally, changing humidity does not affect air filter efficiency and resistance. However, when the air humidity is very high, condensation may form on the filter medium, and there will be a layer of water film on the contact surface between the particles and the obstacle. The larger the contact surface between the two, the greater the bonding force, and the larger particles will no longer bounce back so easily, so for Large particle filtration efficiency may be improved. In reality, if it is so humid that the filter carries water, the performance of the filter may undergo various unpredictable changes. For example, for filter paper made of plant fibers, if the water resistance of the paper is not good, water will soften the paper and compress the fibers, and the resistance of the filter will increase rapidly until the filter is blocked. For another example, if a high-efficiency filter carries water, the dust will be transported to the leeward side of the material by the water. After drying, the filter becomes a dust generator. |
