AIR FILTERATION USING HEPA FILTERS
- 1. By: Shaikh Maaz Zubair Sayyed Mohammad Faiz MHSSCOE
- 2. According to WHO delhi is one of the most polluted cities in the world, with people on risk of respiratory disease. Often the air quality inside a building is worse than the air quality outside Harmful compounds can be found in carpets, building materials, paints and furniture – especially when they are new Air pollution can cause serious health problems, especially for people who are very young, very old, or who have heart or lung problems.
- 3. Sick-Building Syndrome Sick-building syndrome is a set of symptoms, such as headache, fatigue, eye irritation, and dizziness, that may affect workers in modern, airtight office buildings. Sick-building syndrome is believed to be caused by indoor air pollutants. Sick-building syndrome is most common in hot places where buildings are tightly sealed to keep out the heat.
- 4. What is a HEPA FILTER? HEPA is an acronym for “High Efficiency Particulate Air” This type of air filter can remove at least 99.97% of dust, pollen, mold, bacteria and any airborne particles with a size of 0.3 micrometres (μm) • Human Hair: 50150 microns • Household dust and lint: 0.01100 micron • Pollen: 10110 microns • Mold: 150 microns • Pet dander: 0.110 microns • Tobacco Smoke: 0.011 micron • Viruses and Bacteria: 0.00110 microns
- 5. Construction: HEPA filter is constructed of borosilicate microfibres in the form of pleated sheet Sheet is pleated to increase the overall filtration surface area. The pleats are separated by serrated aluminum baffles or stitched fabric ribbons, which direct airflow through the filter This combination of pleated sheets and baffles acts as filtration medium.
- 6. HEPA FILTER
- 7. Filtration mechanisms: 1. Inertial Impaction : larger particles are filtered due to the impaction mechanism. Larger particles have higher mass and are harder to turn than smaller particles due to inertia. Because of this inertial effect, the particles continue to travel in a somewhat straight line even though the airstream is turning to move past the fiber. Once the particle comes in contact with the fiber, it becomes attached and is “filtered” from the airstream
- 8. Filtration mechanisms: 2. Diffusion: it is the most difficult air filtration mechanism to imagine or explain. Very small particles come in contact with fibers due to diffusive effects. The particles collide with air molecules and are “pushed around.” This effect is called Brownian motion. Because of Brownian motion, small particles don’t precisely follow the airstream, but instead “vibrate” or move erratically.
- 9. Filtration mechanisms: 3.Interception : In order to be intercepted, a particle must come within a distance from a fiber of one radius of itself. Thus, the particle makes contact with the fiber and becomes attached. The interception mechanism can be contrasted with the impaction mechanism in that a particle which is intercepted is smaller and its inertia is not strong enough to cause the particle to continue in a straight line.
- 10. Overall Design There’s also the powerful combination of an activated carbon pre-filter. That’s double the precaution and filtration. Nothing gets through, dust, gases, or smells. Activated carbon filters or anti bacterial filters are rarely used alone to clean the air, but as a helper they work wonders!
- 11. Function of Pre-filters Having pre-filters inbuilt into purifiers is a hefty advantage over cleaners that don’t. This is the first step in the filtration process where the pre-filters job is to capture large particles the main filter usually can’t, or particles that get stuck to it. It prevents debris getting into the main filter, and this is why pre-filters come in handy as an additional strength in filter technology.
- 12. Anti Bacterial Filters Anti bcterial filter are special in a few ways. similar kind is activated carbon filter. Activated carbon is also called activated charcoal which goes through a process with oxygen to open up the pores between atoms. The main function of activated charcoal is to adsorb the odors or colored substances from liquids or gases.
- 13. PROPOSAL FOR PROJECT (B) The model consist of a powerful fan placed in a timber or plastic frame and installing pre-filter, HEPA filter and carbon filter in front of the fan the edges of the unit will be tape with duct tape to ensure that air will properly flow through the filters and the fan. Proposed Design.
- 14. Testing of the model will be done on respiratory dust sampler machine in the environment lab of the college. The output of HEPA filter can be connected on the outside plate of sampler along with the filter paper to test out the concentration of particulate matter removed by HEPA filter in the room. A typical dust sampler at environment lab of MHSSCOE