HEPA FILTER: WHAT IT IS AND WHY YOU NEED IT
When it comes to cleaning, we cannot fail to mention vacuum cleaners, and therefore their filters. Different types are available to meet the most specific needs. This is why a very important element to evaluate before buying a vacuum cleaner. We have chosen to focus on the HEPA filter to understand what it is and why you might need it.
WHAT IS A HEPA FILTER?
HEPA stands for High Efficiency Particulate Air, which is a mechanical filtration system. This type of filter was developed by nuclear scientists to help remove radioactive particles. Subsequently, HEPA filters were used for many applications including for vacuum cleaners, both domestic and professional. They are chosen for their extraordinary filtration efficiency, which is why they are also called absolute filters. In fact, they have the ability to capture very small particles, down to 0.3 µm (micrometers). To understand better, here are some examples:
- Human hair: 50-70 µm
- Fine sand 90 µm
- PM 10: particulate made up of particles with dimensions less than 10 µm
- Red blood cells: 7 µm
- PM 2.5: fine particles with a diameter of less than 2.5 µm
- Bacteria: 0.2-5 µm
- Virus: 0.01-0.3 µm
HOW A HEPA FILTER IS MADE AND HOW IT WORKS
The HEPA filter is composed of microfiber filter sheets, thousands of glass fibers that intertwine with each other in multiple layers, separated by aluminum septa. These layers of filter sheets have the task of blocking the polluting particles present in the area to be treated.
The HEPA standard, born in America, requires filters to effectively retain a minimum percentage of 85% of particles up to the size of 0.3 microns, depending on the level classes. HEPA filters can block these particles in various ways, using an air flow, depending on their size:
Interception: Larger particles are physically blocked by the filter fibers
Impact: medium-sized particles only partially follow the flow of current and with the impact they are still trapped between the filter meshes.
Diffusion: the smallest particles bang against each other and behave more irregularly, but are slowed down by diffusion and knocked down by inertia.