HEPA filters are used in many household and industrial devices. Vacuum cleaners, air cleaners, air conditioners, cleaning robots and air humidifiers are equipped with them. Their functionality is especially appreciated during the ongoing SARS-COV-2 coronavirus pandemic. Why? We'll explain everything in today's article. We will discuss what a HEPA filter is, what it removes, what it is made of and what its prices are.
WHAT IS A HEPA FILTER?
The HEPA filter (High Efficiency Particulate Air Filter) is a special type of filter that is highly effective in removing impurities. Its design makes it can retain particles even with a diameter of 0.3 μm. It consists of thin sheets made of polypropylene, which are shaped like a harmonica. This shape allows for free air flow, but at the same time it has a large surface, that effectively absorbs all impurities. HEPA filters are classified according to the EN 1822-1:2009 standard.
The principle of operation of this type of filter is very simple. Its fibres form a dense mesh with microscopic pores. They are small enough to keep almost all possible pollutants (including bacteria and viruses), but at the same time, they allow for the free flow of air. HEPA filtration is accomplished through 4 types of mechanisms: diffusion, inertia, sieving and interception. What do they mean?
Sieving – dust particles and microbes are trapped in the fibres of the filters while air can freely circulate around them.
Inertia – applies to larger and heavier particles that have a greater mass than air. Due to the force of inertia, they do not follow the same direction as air and fall directly onto the filter fibres.
Diffusion – this phenomenon helps to trap the smallest particles which moving in irregular directions, are captured by the filter fibres.
Interception – this can be called otherwise "sticking" of dirt to the fibres on the filter. Medium-sized particles, that follow the movement of air, are susceptible to interception.
HEPA FILTER DESIGN
HEPA filters are made of glass fibres. This type of material is effective at capturing particles ≥ 0.01 μm in diameter and can retain up to 99.995% of 0.3 μm particles. What do these numbers mean? Among other things, HEPA filters trap not only dust particles, but also cells of microorganisms, such as fungi, bacteria, viruses and protozoa.
However, it should be noted that the filter only stops, and does not combat contamination. Therefore, it is important to replace used filters on an ongoing basis or, in the case of washable models, to rinse them regularly with water. Additionally, filters of this type, used on an industrial scale, are equipped with aluminium sheets, which strengthen them and increase their efficiency. Many devices also use pre-filters (with a simple mesh structure) which are designed to catch the largest dust particles. Otherwise, they could very quickly clog and disrupt the operation of the HEPA final filter.
Sometimes, except for the main and pre-filter, special cartridges containing activated carbon are also used. Such a treatment system filters not only large and microscopic solid pollutants, but also volatile organic compounds (VOCs). Carbon filters also absorb unpleasant odours, such as, for example cigarette smoke.
HEPA FILTERS APPLICATION
HEPA filters are famous for their extreme efficiency in retaining microparticles. Depending on their class, they are able to catch up to 99.995% of dirt with a diameter of 0.3 μm. This makes that filters of this type can be used wherever the highest quality and cleanliness of air is important. They are used in air conditioning systems and cleaning devices in such establishments and places as:
- hospitals
- clinics
- treatment rooms
- pharmaceutical plants
- laboratories
- electronics production lines
- halls with food
- military shelters
- schools, colleges and nurseries
- hotels and conference rooms
- restaurants, clubs and discos
- supermarkets
Ease of access and relatively low cost of HEPA filters make that they are increasingly used in devices for individual use, such as, for example, household vacuum cleaners. This fact is appreciated by, for instance allergy sufferers, because the high efficiency of HEPA filters allows for quick elimination of dust and other allergens from the air and floors.
The subject of HEPA filters is particularly important in the era of the SARS-COV-2 coronavirus pandemic. Both vacuum cleaners and air conditioning systems equipped with these filters allow for effective air filtration and trap virus particles (including coronavirus, flu and measles virus). There are also protective masks with a HEPA filter on the market, which are used by medical teams. However, you should remember about what we mentioned earlier. Filters do not kill microorganisms, they only trap them.
What do HEPA filters remove (trap)?
- bacteria
- viruses
- fungi and mould
- protozoa
- dust and pollen of plants
- dust mites
- fine hair
- particulate matter, i.e. smog components, e.g. PM2.5, PM10, PM1
DIVISION AND CLASSES OF HEPA FILTERS
There are 8 basic classes of HEPA filters, which differ from each other in the filtration efficiency of particles with a diameter of 0.3 μm. These classes are based on the guidelines of the N1822-1: 2009 standard.
EPA E10 – this is the lowest class that has a filtering efficiency of 85%. Devices equipped with a filter of this class are used in, including vacuum cleaners, air conditioners or industrial facilities.
EPA E11 – in this case the effectiveness is 95%. The use of filters of this class is similar to the above.
EPA E12 – this class is characterized by filtering of 99.5%. This means that EPA E12 filters are used in places such as hospitals and laboratories.
HEPA H13 – for this class, the efficiency in air purification is 99.95%, so quite a lot. The use of H13 class filters will be similar to the E12 class.
HEPA H14 – filtering at the level of 99.995%, which includes equipment of this class, is appreciated, for example, in specialized medical facilities.
ULPA U15 / ULPA U16 / ULPA U17 – these are the 3 highest classes of HEPA filters. ULPA stands for Ultra Low Penetration Air. These classes are distinguished by the highest level of filtering at the level of: 99.9995%, 99.999995% and 99.999995% respectively. Where can these types of filters be applied? Certainly, in places with very restrictive air quality requirements. It will include nuclear, pharmaceutical and food industries.
HOW OFTEN CHANGE THE HEPA FILTER?
Manufacturers suggest different dates of periodic replacement of this type of filters. It all depends on the intended use and operating conditions of the device. This period may vary from several months to even 10 years. At this point, it is worth adding that some devices are equipped with a special operating hours meter and automatically inform about the need to replace the filter with a new one. The washable filters, which you can clean yourself using warm water, can be facilitation. It is important, however, to not to brush the filter surface additionally and not to insert it into the device while it is still wet (the filter must be dry completely).
There may also be a question whether it is worth using top-class ULPA filters in home appliances? Of course, it doesn't make sense as the differences in filtering efficiency for HEPA and ULPA grades are so slight that they have no significance in a residential setting. On the other hand, such restrictive standards are needed in specific industries, e.g. in nanocomponent factories or nuclear power plants. In such cases, even the difference between 99.9995% and 99.999995% makes a big difference.
HOW TO WASH THE HEPA FILTER?
We already know that, depending on the type of filter, it can be either thrown away and replaced with a new one, or simply pulled out and washed. So, let's check how exactly to do it. First of all, it is certain that any filter – including the one discussed in this article – clogs in the course of time. It all depends on the conditions in which it is used. In household vacuum cleaners, both washable and disposable filters are available, which should be regularly replaced with new ones. Therefore, before buying a device, it is worth checking what type of filter is used in it.
How to clean HEPA filters? First of all, as it was mentioned before, don’t use any brushes. They can disturb the structure of the filter (even if we don’t notice it), which will worsen its future performance. Due to the low prices of this type of filters, it is the best idea to replace it with a new one immediately (we recommend equipping yourself with a set of spare filters at the time of buying the device).
Washable filters are a slightly different "fairy tale", which are definitely a better choice. Regular maintenance allows you to keep their efficiency at the highest level. How to wash the HEPA filter? First of all, after removing it, check if it really needs cleaning. Just compare both sides of the filter for visible contamination. Then, you can gently clean the filter surface with a cloth and rinse it under
running water (be careful not to accidentally damage it). You will achieve higher washing efficiency when you place the filter under higher water pressure (but do everything with moderation!). Finally, let the filter dry completely and naturally. Before putting it back into the device, make sure it is completely dry!
Can I use detergent to wash the filter? If the dirt on its surface is stubborn and does not want to come off under running water, you can decide to use a small amount of soap or washing-up liquid.
VACUUM CLEANERS WITH HEPA FILTERS – WHY IS IT WORTH HAVING THEM?
Vacuum cleaners are one of the most popular cleaning devices in households. They are cheap, functional, and on the market you can find basic models at prices not exceeding a few hundred zlotys, as well as premium class ones – including dry and wet vacuum cleaners and washing vacuum cleaners. The appearance of antibacterial filters in household vacuum cleaners was the novelty, which turned out to be a highly it can be said that those with innovative filters don’t have any disadvantages. In addition, the prices of vacuum cleaners with HEPA filters aren’t much higher.
What do we gain by buying a modern vacuum cleaner with a high-performance filter? First of all, an unprecedented level of hygiene in the apartment. It will be possible to filter even micro pollutants - including viruses and bacteria. Vacuum cleaners of this type will be the perfect solution for allergy sufferers! They will effectively get rid of even the smallest dust particles - including mite droppings, which are a popular allergen.
CORONAVIRUS SARS-COV-2 AND HEPA FILTERS H14
It's hard, when discussing the effectiveness of HEPA filters, not to mention the spreading SARS-COV-2 coronavirus pandemic. Most public institutions, healthcare facilities, enterprises as well as individual users around the world began to pay more attention to maintaining personal hygiene and air purity in the surrounding space.
More than once, on the Internet you can come across the question: Does the HEPA filter kill the coronavirus? It can be said yes and no. First of all, the virus itself is not a living organism from a biological point of view, so it must be talked about neutralizing the virus, not killing it. So, can HEPA filters trap coronavirus particles?
Yes, but only highly effective ones, i.e. at least H14. The SARS-COV-2 virus has a diameter of 0.12 to 0.16 μm. So, it can be seen that it is definitely close to the permeability of the HEPA filters, which is ≥ 0.01 μm. So, if we are looking for a home vacuum cleaner or purifier that will effectively filter the air from virus particles, let's look for equipment with filters with at least HEPA H14 class.
ANTI-VIRUS MASKS WITH HEPA FILTERS
High-performance filters are used not only in washing and cleaning devices, but also in personal protective equipment. This is a very important factor in the fight against the ongoing SARS-COV-2 coronavirus pandemic. As already known, high-class filters are able to effectively stop microorganism particles, such as bacteria or viruses. This makes masks equipped with HEPA filters a basic equipment for medical teams and hospital staff.
HEPA FILTERS IN INDUSTRY
We mentioned that due to the affordable price and high availability, various types of equipment equipped with HEPA filters are becoming more and more popular among households. Still, this
technology is most commonly present in many industries. For example, industrial vacuum cleaners – including professional vacuum cleaners and special industrial vacuum cleaners – are equipped with these filters. Machines of this type are adapted to the suction of not only heavier and larger pollutants, but also the abrasive and hazardous materials generated during the processing of building materials.
WHAT IS THE CADR FACTOR?
CADR, i.e. Clean Air Delivery Rate stands for the amount of clean air that a device equipped with a filter can deliver. This ratio can easily tell you what the actual performance of your equipment is in a particular area. The CADR value will be slightly different from the maximum air flow. It is blocked to some extent by the filter. CADR is the most common in the technical data of air conditioners and air purifiers. With its help, equipment manufacturers determine the equipment performance. Most often, the CADR value is assigned separately for solid and gaseous pollutants (the latter are removed more slowly).
HEPA FILTERS PRICES
After reading the article, the final question may arise: how much do HEPA filters cost? Is it quite an expensive investment? Someone may say that this is an investment in your own health and the health of your loved ones, and therefore you cannot save on what is most important to us. But let's leave this dry dispute aside and look at the facts. Why? Because HEPA filters for domestic use aren’t expensive! Similarly to cleaning devices equipped with this type of filter. Example? It will be, for example, the line of Nilfisk household vacuum cleaners. Reliable, efficient and effective home vacuum cleaner Nilfisk One WB10P05A costs just over PLN 500 and is equipped with an EPA 10 class filter in standard equipment. However, more efficient filters up to HEPA 13 class can be used.
To sum up, HEPA filters are a relatively inexpensive and effective method of cleaning the air from micro pollutants. The simple design of HEPA filters also contributes to their trouble-free operation. All these aspects are especially important now, when the coronavirus pandemic is growing and more and more effective methods of air filtration are being sought. As you can read from the article, the highest-class HEPA filters are able to trap small particles such as viruses and bacteria. The most important, however, is that all this technology is also available in household cleaning and filtering devices. Thanks to this, we can take care of micro-pollutant-free air in our apartments at a low cost.
PRODUCTS WITH EFFICIENT FILTERS IN ISPRZET
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