What are the common problems of using HEPA filters in home air sterilizers?What is the working principle of HEPA filters?

Home Air SterilizerHEPA filterWhat are some common problems with use?HEPA filterHow does it work?

The ecological environment has become one of the focuses of common and close attention of all people, in which the attention of air pollution problems such as air pollution, air purification, exhaust pollution and other air pollution problems is also gradually rising. In this regard, there are also more and more families using air sterilizers to solve the problem of indoor air pollution, including outdoor air dust, car exhaust, second-hand smoke, odors and so on. At present, most families use air sterilizer used by the filter is HEPA filter, HEPA filter pore size is very fine, when the air disinfection cleaner in operation, the air can pass through the coarse filter diameter smaller pollutants will be adsorbed, these particulate pollutants not only contain airborne dust, smoke, but also mixed with a variety of microorganisms in the environment.

At present, the air disinfector (or purifier) has realized disinfection and purification as a whole, compared with the traditional air purifier single purification role, air disinfection and purification machine can solve more environmental problems. With the use of air sterilizers over time, HEPA filter adsorption of particulate pollutants, the number of microorganisms will be more and more, and the nitrogen contained in the dust plus the adsorption of "water vapor" for many microorganisms to provide and a better environment, which may contribute to the reproduction of a large number of microorganisms, resulting in the secondary pollution of indoor air. At the same time, the air sterilizer itself equipped with photocatalysts, ultraviolet lamps, plasma generators and other sterilization equipment, can effectively solve this problem.

In the atmospheric environment, especially in more populated public places, the number of fungi, bacteria, viruses and mycoplasmas in the suspended particulate matter in the atmosphere is up to hundreds of species, including pathogens that can cause respiratory diseases such as influenza, mumps, asthma, such as Staphylococcus aureus, mumps virus, and so on. Although most microorganisms are invisible to the naked eye, you need to know about them to better protect yourself and your family.

Studies have shown that the number and types of microorganisms gathered in the ventilation system of air conditioners are more numerous and contaminated, so more attention needs to be paid to disinfection when using air conditioners. If the use of air conditioning at the same time, with air sanitizer, for indoor temperature control, indoor disinfection double effect is beneficial to indoor air cleaning. In addition, in the process of air disinfector use, need to pay attention to is regular, timely replacement of HEPA filters, research has found that the number of mold and other microorganisms on the home air purifier filter with the use of time into a positive correlation with the negative correlation with the cleaning and maintenance. Therefore, I would like to remind friends who are using or will be using air sterilizers, remember to clean and replace HEPA filters in a timely manner.

So what is a HEPA filter?

Speaking of HEPA filters, HEPA has basically become the standard configuration of air purifiers, from a few hundred dollars to tens of thousands of dollars of purifiers HEPA filters carry a very large number of filtration roles.

High-Efficiency Particulate Air, or High-Efficiency Particulate Air Filter, or HEPA for short, is made of very fine fibers interwoven with a strong ability to capture particles, small pore size, large adsorption capacity, and high purification efficiency. According to the single filter net rate calculation, the standard HEPA filter can filter the air from small to 0.3 micron (hair diameter of 1/200) particles, filter net rate of at least 99.97%, is the haze, as well as bacteria, viruses, fungal spores and other pollutants of the most effective filtration medium, the best filtration performance can be 99.999995%, that is, every 20 million particles, can only have 1 particle, but not 1 particle. In other words, for every 20 million particles, only 1 particle can penetrate the HEPA filter membrane. At present, it is internationally recognized as a high-efficiency filtration material.

What material is the HEPA filter made of?

Currently on the market HEPA material is mainly divided into PP (polypropylene) high-efficiency filter paper, PET filter paper, PP and PET composite high-efficiency filter paper and glass fiber high-efficiency filter paper. Among them, PP (polypropylene) is paper, therefore, generally can not be washed!

1、PP high efficiency filter paper

It is a new type of filtration material made of polypropylene by special hot melt method, the product is acid and alkali resistant, corrosion resistant, high melting point, stable performance, non-toxic, odorless, uniform distribution, low resistance, high efficiency, high strength, environmental protection, etc. The filtration effect of PP fiber can be achieved at the highest level of H14.

2、PET filter paper

It is made of polyester resin and other materials meltblown, high hardness, good stiffness, corrosion resistance, high temperature resistance, stable performance, but PET single filtration is relatively low, generally can only do H10-H11 level (90% ~ 99.5%), commonly used in sweepers, vacuum cleaners and other filtration precision requirements of the household electrical appliances or large-scale cleaning machine above.

3、Glass fiber high efficiency filter paper

Glass fiber high-efficiency filter paper, a very high gold content filter paper, has previously been used in the nuclear industry. Compared with plastic fibers, glass fibers are characterized by high temperature resistance, high dust holding capacity, good stability, durability and long life. Its most important advantage, however, lies in the fact that it guarantees a sufficiently high filtration efficiency in a single pass. Until today, the highest efficiency of the U15 ~ U17 filter, basically still mainly glass fiber. But the improvement of the filtration effect also brought about by the increase in wind resistance, normally more than 200Pa, can only rely on the increase in fan power to alleviate the lack of air volume.

How HEPA filters work:

1. Sieve effect

When the size of the gap between media compositions (fibers, sieves, corrugated metal, etc.) is smaller than the particle diameter, the filter is designed to capture these particles. This principle is widely used in most filter designs and is entirely dependent on particle diameter size, media spacing and media density.

2. Inertia effect

The rapid change in air direction and the principle of inertia are utilized to separate large quantities (particles) from the air stream. Microparticles at a certain velocity tend to maintain that velocity and continue in the same direction. This principle is generally applied if the process particle concentration is high. And, in many cases, both the pre-filter mode and the more efficient final filter use this principle.

3. Interception effect

In order to achieve interception, a particle must enter from within a distance of a fiber radius. The particle thus comes into contact with the fiber and adheres to it. The difference between the interception principle and the embedding principle is that the intercepted particles are small and their inertia is not sufficient for the particles to continue in a straight line. They therefore flow with the air until they come into contact with the fibers.

Dust smaller than 1μm does not move with the airflow, but does "Brownian motion" due to the impact of air molecules. If it hits on the filter fiber, it will be captured. Therefore, the smaller the particle, the more intense the Brownian motion, the better the filtration effect.

Particles are filtered by van der Waals forces, also known as electrostatic adsorption. The filtration of particles below 0.3 microns, such as viral bodies, relies mainly on this effect.