High efficiency HEPA filters, how do they work?

The HEPA filter was developed during Wolrd War II and has since evolved for other applications such as the Manhattan Project, a nuclear research and development program in the United-States.

A HEPA filter is a high efficiency aboslute air filter that filters 99.997% of particules mesuring 0.3 micron or less. These particules float in the air by hanging on to fine droppelettes measuring around 5 microns. The mix of droppelettes and particules are then trapped in the filter. It is composed of a layer of fiber spaced out at a maximum of 0.3 mciron that acts like a membrane at the passage of particules. As shown on the image, particules hit the fibers of the fabric when they are pushed by the air flow, breaking their inertia, causing them to get caugh. The lifespan of a HEPA filter may vary depending on its usage, a pressure indicator or another device can be used to indicate when the filter needs to be changed.

These filters were designed to be used in places demanding the highest degree of filtration and where the risk of contamination by airborn particules is very high. Hospitals favor filtration systems with HEPA filters, especially for operating rooms. They can also serve for the food industry, the pharmaceutical industry, the nuclear industry and many more.

Our pathogen aspirator, the MAXIMED, is a filtration unit equipped with a HEPA filer of 24‘’ X 24’’ X 11.5’’. The particules are pulled by the arm, to optimize a source capture, and sent off to the filter which is the heart of our unit. The microscopique particules are filtered and trapped at its surface. The filter prevents transmission of viruses, like the coronavirus, to patients or to hospital workers.