Hepa Filter

HEPA Filter or High-Efficiency Particulate Air Filter is a special kind of air filter. These filters are used to keep a check on the amount of bacteria to keep the environment bacterial free and sterile. 
As per the standards set by the US government, an air filter must be able to remove 99.97% of all the particles greater than 0.3 micrometer from the air in order to qualify as HEPA. In other words, this filter should be so efficient that it allows only 3 particles to pass through for every 10,000 particles that enter the filter within its filtering range. 
In order to ensure quality of performance, these devices must be properly designed, regularly tested, certified, and re-certified by qualified personnel.A typical HEPA filter consists of a randomly arranged fiber mat. The fibers are usually made up of of fiberglass with diameters ranging between 0.5 and 2.0 micrometers.The key parameters that affect the functioning of a HEPA filter are the fiber density, diameter, filter thickness, and face velocity. 
Like membrane filters, particles that are as wide as the largest opening or distance between fibers cannot pass in between them at all. But HEPA filters are designed to prevent much smaller pollutants from passing through as particles mainly stick to the fiber through the applications of mechanisms like diffusion, interception, and impaction. Thus the common assumption that this filter acts like a sieve where all the particles smaller than the largest opening can pass through is incorrect. 
These filters can prevent of the spread of airborne bacterial and viral organisms and are widely used in hospitals, pharmaceutical industries, semi conductor industries, surgical disposable industries etc. These filters have several applications in the field of biomedicine. Some special type of HEPA filtration systems used for biomedical purposes also come equipped ultra-violet light units to destroy the bacteria and viruses trapped by the filter. IT works as a barrier for the 
Airflow and doesn't allow the particles bigger than 0.3 microns to passon. HEPA filter is always used after one or two prefilters to enhance the performance and the life of the filter.

In today's world, this filter finds wide application in making clean rooms of class 100, class 1000, class 10000 and class 100,000 The different classes of clean roms are made for different application and these filters are used in the same in different configuration to achieve the desired air cleanliness level.