What is a HEPA high efficiency filter? What are air purifier HEPA filter ratings?

What is a HEPA high efficiency filter? Air PurifierHEPA filterWhat are the grades like?

Whenever you go to buy a purifier, the salesman will recommend bringing aHEPA filterThe. You might think that the salesman is trying to get more commission by specifically recommending the expensive ones to consumers. In fact, the salesman is really not trying to trap you, HEPA filters are really better!

Whenever the high incidence of haze, air purification products have become the best-selling products in the north of the Yangtze River, people always feel that buying an air purifier placed in the home can make the indoor air become cleaner. Generally speaking, when we buy air purification products, we will focus on the filtering effect of its supporting filters. Because in our cognition, the higher the filtration effect of air purification products, the better. In fact, this is not unreasonable, because the filter as the heart of the new air system, the merits of the filter directly affects the purification ability of the new air machine.

What is a HEPA high efficiency filter

HEPA high-efficiency filter is interwoven by high-density fibers, which has a strong ability to capture particles, large adsorption capacity, high purification efficiency, and a very obvious effect of filtering particles. HEPA high efficiency standard filter, for 0.1 micron and 0.3 micron purification rate of 99.998%. if you use it to filter cigarettes, the filtration effect can almost reach 100%, because the particles in the cigarettes between 0.5 to 2 microns, can not pass through the HEPA high efficiency filters. HEPA filter grade

Due to the different filtration effects of different filters, the filter level in the new air conditioner also has a strict classification. At present, we commonly used European standards are generally divided into 17 levels from G1 to U17, of which the best U17 level of HEPA filter purification efficiency can even reach 99.999997%. If divided according to Chinese standards, generally divided into rough, medium - medium-high efficiency, sub-high efficiency - high efficiency and ultra-high efficiency of a total of four grades.

From the chart below, the European standard F7-F8 is known as the high efficiency filter; F9-H11 is known as the sub-efficient filter, H12-H14 is known as the high-efficiency filter, and U15-U17 is known as the ultra-high efficiency filter.

In addition to the common European standard and the Chinese standard, there is also an uncommon American standard MERV. the American standard is divided from C1 to UH20, with a total of 20 grades. Unlike the European standard, the purification effect of M13 in the American standard is roughly equivalent to F7 in the European standard, which belongs to the high and medium efficiency filter, while UH17 in the American standard is only roughly equivalent to H13 in the European standard, which is what we call the high efficiency filter. Therefore, in order to ensure that the air purification to get the best results, we in the choice of new air conditioner is best to choose the filter level in the H12 (or high-efficiency) above the filter, so as to fundamentally solve the problem of PM2.5.

Some people ask, since the high-efficiency HEPA filter can filter most of the tiny particles, then why many air purification products will have the existence of primary filters? In fact, this is to extend the service life of HEPA filters. The primary filter can filter out some large particles, so that the HEPA filter to focus on filtering the finer particles, reduce the burden of the HEPA filter. In addition, the price of primary filters is lower than that of HEPA filters, which also reduces the cost of replacing HEPA filters frequently. Therefore, in the new air conditioning system, primary, medium and high efficiency filters are generally not used alone, but two or three with the use. Fitted with more than two layers of filters, in order to achieve better air filtration effect.

HEPA filters include four filtration mechanisms. The first one is the blocking mechanism, which works on large particles.

The second mechanism for the effect of gravity, the volume of small dense particles, through the HEPA filter when the speed of movement will be reduced, the natural settlement to the HEPA, this process is somewhat similar to the sediment in the water downstream of the river settlement process.

The third mechanism is the influence of airflow. Because the HEPA filter weaving is not uniform, constituting a lot of air vortex, ultra-small particles are affected by this cyclone adsorption in the HEPA filter to complete the filtration intention.

The fourth filtration mechanism for ultra-fine particles in the Brownian motion effect of impact to the HEPA filter fibers by van der Waals force, was filtered.