HEPA filters explained

The first HEPA (High Efficiency Particulate Air) filters were developed in the 1940’s during the development of the atomic bomb by the U.S. Atomic Energy Commission.

The purpose of the HEPA filters was to be able to remove virtually all radioactive particles as small as 0.3 micron. In this they succeeded admirably as HEPA filters are supposed to filter up to 99.97% of particle greater than 0.3 micron. But remember that this under ideal laboratory circumstances.

With a HEPA filter you can expect to remove among others: some bacteria, fungi, micro organisms, pollen. A HEPA filter will not remove: viruses, smoke, fumes, and odors.

Commercial HEPA filters are, among others, found in hospital isolation rooms, operating theaters, as well as in industrial clean rooms.

The filter is generally made of synthetic fibrous materials with a denseness similar to blotter paper.

The way a HEPA filter works is not by trapping a particle in between the fibers – like catching a fish in a net. Rather what happens, is that the air flow will slip around the fibers, but the particles can not change direction so quickly, and will hit the fibres and keep sticking to it.
Due to the just described mechanism, in theory these filters can catch particles as small as viruses, but in practice this is not the case.

HEPA filters come in various sizes, they can be anywhere between 2’ and 12” thick. Because of the high density of the filter, a lot of energy has to be expended to force the air through the filter. This tends to make HEPA air cleaners rather noisy and costly in operation.

A HEPA filter lasts between 2 and 5 years.

For more information on related products, please choose from the following:

HEPA Air Cleaners |Electrical / Ionic Air Purifiers | Ozone Air Purifiers | Whole House Purifiers | Replacement Filters