HEPA is an acronym which stands for High Efficiency Particulate Air. HEPA filters provide a very high level of filtration efficiency for the smallest as well as the largest particulate contaminants. Generally speaking, particles retention is achieved by multiple mechanisms of HEPA filter working together including sieving, interception, inertial impaction and diffusion. Now let's learn the HEPA working principle.
Maybe you don't know that a HEPA filter must capture a minimum of 99.97% of contaminants at 0.3 microns in size. The 0.3 micron benchmark is used in efficiency ratings, because it approximates the most difficult particle size for a filter to capture. HEPA filters are even more efficient in removing particles that are smaller than 0.3 microns and larger than 0.3 microns. The fact that a HEPA filter's removal efficiency increases as particle size decreases below 0.3 microns is counter intuitive. However, this is a proven and accepted fact in the filtration sciences.
Now let's get to know the HEPA Box working principle. It can be divided into three stages. In the first stage, inertia works on large, heavy particles suspended in the flow stream. These particles are heavier than the fluid surrounding them. As the fluid changes direction to enter the fiber space, the particle continues in a straight line and collides with the media fibers where it is trapped and held. In the progress of diffusion, diffusion works on the smallest particles. Small particles are not held in place by the viscous fluid and diffuse within the flow stream. As the particles traverse the flow stream, they collide with the fiber and are collected. After diffusion, direct interception works on particles in the mid-range size that are not quite large enough to have inertia and not small enough to diffuse within the flow stream. These mid-sized particles follow the flow stream as it bends through the fiber spaces. Particles are intercepted or captured when they touch a fiber. Finally, Sieving, the most common mechanism in filtration, occurs when the particle is too large to fit between the fiber spaces. A HEPA filter would follow the same filtration principles but would have total filtration efficiency greater than 99.97%. In other words, the worst that a HEPA filter would perform would be to capture 99.97% of particles.
Since most contaminants fall into that category, just imagine how much of an impact these Washable Panel Filters have on the quality of air you breathe. Stuff like dust, allergens, pollen, dust mites, pet dander, mildew and mildew spores are eliminated with the use of a HEPA filter, especially useful for people who suffer with asthma or hay fever.
As stated above, you must have understood the HEPA working principle. We hope this information is useful for you. If you are in need of HEPA filter, you can visit www.hefilter.com to get more information.
