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Hepa Air Filters When? Where? How? And Why?



History

During the late 1940s the US Atomic Energy Commission and the US Army came up with a solution for treating those who had been exposed to radioactive warfare chemicals. And the answer came in the form of the first ever, fully developed HEPA air filter.

The new invention was initially labeled as just a ‘collective protector filters’, but it was quickly renamed to the current acronym standing for ‘High-Efficiency Particulate Air’. Surprisingly, the primary use of the device was as part of an atomic bomb in the ‘Manhattan Project’. It was soon declassified and allowed to be manufactured as commercial and residential equipment.

Functioning

All HEPA devices use a pre-filter medium that is composed entirely of nylon or foam. This pre-filter essentially traps larger particles in the air and allows the main HEPA filter to last longer and perform at its optimum capacity. The HEPA air filters use a unique configuration of fiberglass that makes their arrangement deterrent to all contaminants present in the flow of air such as allergens, dust particles, and mold. The most prominent principle used by the device is the process of using adhesive layering which is able to trap contaminants on contact and allow clean air to circulate freely.   

The methods common to all such devices to function properly include:

  1. Interception – where particles in the air are blocked by the fibrous material within a restricted radius.
  2. Impaction –larger particles become embed into one another with higher flow of air and decreasing the distance between fibers. This allows for better entrapment of airborne particles at an increased pace.
  3. Diffusion – making use of Brownian Motion, this enhanced mechanism causes particles as small as 0.1 micron (1 millionth of a meter or 10-6 meter) to be delayed within the filter and be caught using the two methods above.

It is important to note that for any HEPA filter to be recognized as a true HEPA filter, it must maintain a 99.97% efficiency at all times and should not allow more than three particles out of a total of 10,000 to penetrate the filtration medium. All filters that do not fulfill this criteria set by the DOE (United States’ Department of Energy) are disqualified.

Uses

There are a lot of uses for a hepa air filter. Some of the notable ones are mentioned below:

Air Purification

The most common and widely accepted usage of the device is to filter and purify air. Ever since their conception, and over the past 20 years of user experience they are now also being used to clean air in commercial, residential, institutional, and Industrial working environments.

Medical Usage

Whether it is in an operating theatre for a surgery, or filtering cabinets in hospitals and clinics for biological safety, the device is effective in keeping the air clean.

One major shortcoming of this technology is that it is unable to remove odors and gases from air. However, this can be overcome by coupling the HEPA filter with other devices.

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