German
French
Italian
Portuguese
Japanese
Korrean
Russian
What are the main factors influencing the effectiveness of HEPA filtration?
What are the main factors influencing the effectiveness of HEPA filtration?Many people have the misconception that the larger the size of the particles, the greater the removal capacity of the HEPA filterHEPA relies on van der Waals forces between fine particles and solids and is therefore effective for 0.5 microns and 0.1 microns. The filtration efficiency of the fine particles is very good. Because particles at 0.1 microns perform Brownian motion, the smaller the particle, the stronger the Brownian motion, and the more impacts it receives, the more effective the adsorption. Particles larger than 0.5 microns have inertia. The greater the mass in motion, the greater the inertia and therefore the more effective the filtration. In contrast, particles with a diameter of 0.1 - 0.3 microns are difficult to remove 1. Sieving effect When the gap size between the media components (fibers, mesh, corrugated metal, etc.) is smaller than the particle size, the filter is designed to capture these particles. This principle has been widely used in most filter designs and is entirely dependent on particle size, media spacing, and media density. 2. Inertia effect Using the principle of rapid change in air direction and inertia, large quantities (particles) are separated from the air stream. The particles tend to maintain this velocity at a certain speed and remain moving in the same direction. If the process particle concentration is high, this principle is usually used. Furthermore, in many cases, this principle is used in the pre-filter mode as well as in the more effective final filter. 3. Interception effect To achieve interception, the particles must enter the radius of the fibers. Therefore, the particles come into contact with the fibers and adhere to them. Compared to the embedding principle, the interception principle differs in that the intercepted particles are smaller and do not have sufficient inertia to keep them moving in a straight line. It, therefore, flows with the air until it comes into contact with the fibers. 4. Diffusion effect Dust smaller than 1 μm does not move with the air stream but undergoes a "Brownian motion" due to the influence of air molecules. If it touches the filter fibers, it will be captured. Therefore, the smaller the particle, the stronger the Brownian motion and the more effective the filtration. Therefore, HEPA filters are not like sieves. When particles are smaller than 1 μm, the smaller the particles, the easier they are to remove. Conversely, particles that are too large or too small, especially those of 0.3 μm, are the most difficult to remove. |
