Air Filtration

For years, the main reason for the use of air filters has been keeping ventilation components clean and preventing contamination of indoor surfaces. Although these are still important today, as our knowledge of indoor air pollutants increases, it has been understood that the main reason for their use is to protect human health. Selection and maintenance of air filters should be done with this in mind.

The air filtration system is the first method of defense against airborne contaminants. Sufficiently efficient, correctly selected air filters provide the desired air cleanliness for human health and protect the building and mechanical equipment.

All particles carried in the air have an effect on human health and comfort. However, considering indoor air quality, particles of 2.5 µm and smaller should be given much more importance. Air filters should be selected based on this criterion: the higher the efficiency of the air filter for particles 2.5 µm and smaller, the better the quality of the air supplied to the environment.

Filtration and energy

With cleaner air, the energy expenditure required for heating and cooling is significantly reduced. Dust accumulating on dirty coils causes heat transfer not to work at design value and to show low efficiency. An annual loss of 5% in ventilation energy is a larger expenditure than the cost of a high-efficiency filter. High-efficiency filtration also keeps the ducts clean; otherwise, the ducts require frequent cleaning, which means new costs.

A highly efficient filtration system should be understood as preventive maintenance and savings that can pay for itself in a very short time, for health and high production capacity of employees, and for building management and operation.

What is a HEPA filter?

The HEPA filter with the lowest particle capture efficiency is defined as the H10 class, while a HEPA filter with the highest possible particle capture efficiency is in the H14 class. HEPA filters are the most effective solution to remove harmful airborne pathogens from the air we breathe, and H14 class HEPA filters come to the fore when the highest possible precaution level is required, because their fibers can capture very small particles such as coronaviruses and many similar nano-sized particles.

The minimum efficiency of HEPA filters is 99.95% for H13 class and 99.995% for H14 class at the most penetrating particle size (MPPS) according to the EN 1822 standard. When 100,000 particles with MPPS value pass through an H14 class filter, the maximum number of particles that can pass is 5.

HEPA filters and COVID-19

Particles of 1 µm and smaller pose a higher risk to human health. Coronavirus is in the size range of 0.08 to 0.16 microns; the minimum particle size that HEPA filters can hold is between 0.20 and 0.9 µm. Considering that a human hair has an average thickness of 110 µm, the importance of HEPA filters can be understood.

Do HEPA filters keep the virus? Yes: HEPA filters keep viruses to the extent of their efficiency value. HEPA filters are used in hygienic applications such as hospitals, pharmaceutical factories, and food and beverage production facilities. In hospitals, they are located especially in operating rooms, intensive care rooms, isolation rooms, and biosafety cabinets.

> Two inline diagrams from the source page remain under asset review and are not yet included.