Household air purifier, the circle inside teaches you how to choose!
An air purifier is a household and similar electrical appliance that has a separate air filtration system and has certain removal capabilities for particulate matter, gaseous pollutants, microorganisms, and the like in the air.
From the definition, we can see that purifying indoor air pollutants is the main function of air purifiers. These pollutants specifically refer to:
Particulate pollutants mainly include dust and pollen in the air.
Solid or liquid particulate matter suspended in the air (whether long-term or short-term) is called particulate contamination due to damage to biological and human health. There are many types of particulate matter, generally referring to dust particles, dust, mist, smoke, chemical fumes and soot between 0.1-75 μm. The hazard is characterized by the fact that the particle dust having a particle size of 1 μm or less is slowed down and the surface is large and far.
As we usually say, PM2.5 is a kind of particulate matter that can enter the lungs. Its diameter is less than 1/20 of the thickness of human hair. However, it has large particle area and strong activity, and it is easy to attach toxic and harmful substances (for example, heavy metals, microorganisms, etc., and have a long residence time in the atmosphere and a long transport distance, thus having a greater impact on human health and the quality of the atmospheric environment.
Many people don’t care about pollen. They think that pollen will not affect themselves. In fact, during the high pollen period, sneezing, runny nose, tears, stuffy nose, etc. are all manifestations of pollen allergy symptoms. It is not obvious and we are automatically ignored.
There are two main types of gaseous pollutants, one is the original pollutants discharged directly from the pollution source into the atmosphere, such as sulfur oxides, nitrogen oxides, carbon oxides, and organic compounds; the other is through a series of chemical or photochemical New pollutants generated by the reaction, such as sulfuric acid fumes, photochemical smog, ozone, acetyl nitrate, ketones, aldehydes, and the like. At present, consumers and businesses pay more attention to formaldehyde.
Because the decoration materials are “not closed”, formaldehyde is the leader of indoor pollution, and it is also a unique pollution problem for Chinese families. Formaldehyde raw materials will be attached to the wardrobe, floor, and paint, and it is a long-term volatile process. At the same time, harmful pollutants such as formaldehyde and benzene are also high pollutants. The incidence of “acute leukemia” is mostly caused by the renovation of the family. It is a long-term hazard and a serious hazard. It is the most important characteristic of gaseous pollutants such as formaldehyde.
Airborne microorganisms refer to microorganisms that are present in the air. Humans, animals and plants, and microorganisms in the soil can be dispersed in the air by droplets or dust, and exist in the form of aerosols. The aerosol is a colloidal dispersion in air composed of particles. The liquid particles are fog, and the solid particles are smoke. They can be suspended in the air for a long time so that the air contains certain kinds and amounts of microorganisms.
There are usually no pathogenic microorganisms in the air, and pathogenic microorganisms entering the air are generally easy to die. Only some of the more resistant pathogenic microorganisms can survive in the air for a period of time, such as Staphylococcus aureus, pneumococcus, streptococcus, tuberculosis. Bacillus, Bacillus anthracis, Clostridium tetanus, etc. These microorganisms exist and spread in the air in the form of aerosols, and healthy people or animals are often infected by inhalation.
What are the main purification technologies for air purifiers?
Commonly used air purification technologies include: adsorption technology, negative (positive) ion technology, catalytic technology, photocatalytic technology, superstructure photo mineralization technology, HEPA high efficiency filtration technology, electrostatic dust collection technology, etc.; material technology mainly includes: photocatalyst, activated carbon, Synthetic fiber, HEAP high-efficiency material, negative ion generator, etc. At present, the domestic air purifier products are the most widely used activated carbon, HEAP high-efficiency filter, electrostatic dust removal, and other purification technologies, other dust collection, coalescence, ultraviolet sterilization, negative ions, and other technologies are generally used as additional functions.
Activated carbon filter
Activated carbon is a porous carbonaceous material. Its developed void structure makes it have a large surface area, so it is easy to fully contact with toxic and harmful gases in the air. The strong adsorption field around the activated carbon pores will be toxic immediately. Gas molecules are sucked into the pores, so activated carbon has a strong adsorption capacity and is also the main technology for removing gaseous pollutants. Activated carbon adsorption technology is mainly divided into two categories: physical adsorption and chemical adsorption.
Physical adsorption is mainly for macromolecular organic gases (such as TVOC such as benzene) to adsorb these macromolecular contaminants through the microporous structure of activated carbon itself. Chemical adsorption is mainly for small molecular gaseous pollutants such as (formaldehyde, hydrogen sulfide, nitrogen oxides, etc.). Because small molecules are easily adsorbed and then re-opened to form secondary pollution, chemical treatment of activated carbon is required to The adsorbed gas reacts with the chemical components to achieve the adsorption effect.
HEPA (High-Efficiency particulate air filter), which means high-efficiency air filter in Chinese, has an efficiency of 99.998% for 0.1 microns and 0.3 microns. The HEPA mesh is characterized by air passing through, but fine particles cannot pass. The particle removal efficiency of up to 99.7% for diameters up to 0.3 microns (1/200 of hair diameter) is the most effective filter for smoke, dust, and bacteria (the smoke particles are 0.5 microns in diameter).
The HEPA filter has the advantage of high efficiency and safety. It is the most important technology for removing particulate pollutants in the air, but the disadvantage is that it can only filter out suspended particles and microorganisms, and cannot filter gaseous pollutants.
The electrostatic precipitator air purifier uses a high-voltage direct current electric field to ionize gas molecules in the air, generates a large amount of electrons and ions, moves to the two poles under the action of the electric field force, and encounters dust particles and bacteria in the airflow to make it charged during the moving process. Under the action of the electric field, the charged particles move to the opposite plate of their own charge. Under the action of the electric field, the free ions in the air move toward the two poles. The higher the voltage and the higher the electric field strength, the faster the ion movement speed. Due to the movement of the ions, a current is formed between the poles. In the beginning, there are fewer free ions in the air and less current. After the voltage rises to a certain value, the ions near the discharge electrode get higher energy and speed. When they hit the neutral atoms in the air, the neutral atoms will decompose into positive and negative ions. This phenomenon is called air ionization. After air ionization, due to the chain reaction, the number of ions moving between the poles is greatly increased, and the current between the poles (called corona current) increases sharply, the air becomes a conductor, and the high-strength voltage captures the accompanying bacterial particles, and the instantaneous conductive strike Wear the cell wall composed of protein to achieve the bacteria to remove dust.
Air purifier classification and advantages and disadvantages
The mainstream air purifier products on the market are mainly divided into the following two types:
Mechanical filter air purifier (passive)
Principle: The motor is driven to suck in dirty air. Through the filter screen, the particles in the air are adsorbed on the filter screen to discharge clean air. The common purification process combination is a primary filter, an activated carbon filter, a HEPA filter, a composite filter, and the like.
Advantages: high purification efficiency of particulate matter, high aldehyde removal, and optimization of air.
Disadvantages: The filter should be replaced regularly, otherwise it will become a source of indoor air pollution. The life of the filter is different. In the short 1-2 months, the price of the filter is very different. Due to its different materials and structures, the price ranges from several hundred yuan to thousands of yuan.
Electrostatic precipitator air purifier (active)
Principle: The particles in the air are charged by ionization and then adsorbed on a high-voltage static collecting plate in the purifier. The common purification process combination is a primary filter, an electrostatic dust removal net, an activated carbon filter, and the like.
Advantages: good sterilization and dust removal effect; static collection board can be washed with water, unlike HEPA filter can only be discarded and replaced, the maintenance cost is lower; because there is no fan, the noise will be small.
Disadvantages: Static electricity will produce ozone, and excessive ozone is also a serious hazard to the body; for formaldehyde and other gas pollutants, the treatment effect is very limited.
What are the national standards and technical requirements for air purifiers?
The air purifier is a very mature product, and it is also relatively sound in terms of national standards. There are mainly the following:
Standard version number
Safety of household and similar electrical appliances – Particular requirements for air purifiers
Air purifier energy efficiency limit value and energy efficiency rating
Antibacterial, sterilization, purification
Antibacterial, sterilizing and purifying functions for household and similar electrical appliances. Special requirements for air purifiers
Through the combing of the air purifier standard system, we can see that the evaluation of an air purifier product mainly involves the following indicators:
Safety refers to the protection of the electrical, mechanical, thermal, fire and radiation hazards of the appliance. This is a basic requirement for electrical products.
CADR (clean air volume)
This refers to the volume of clean air output after filtering through unit time, in m3/h. The CADR values are different for different contaminants.
CCM (cumulative purification)
When the CADR value is reduced to 50%, the total weight of the purified pollutants is accumulated. The unit is mg.
Purification energy efficiency
Purification energy efficiency is an energy efficiency indicator, which indicates that the amount of clean air generated by the unit purifier of the top-rated HEPA air purifier at rated power is calculated by dividing the CADR value by the input power, and the unit is m3/(W ▪H).
The standby power of the energy-saving purifier is not more than 2W.
The rate of antibacterial (sterilization) is greater than or equal to 50%.
The noise limit generated by the operation of the machine under the maximum CADR.
Hazardous substance release
Ozone, UV, TVOC, and PM10 should meet the requirements of the national standard.
Therefore, for the company to declare that the air purifier products meet the above requirements, especially those certified by third-party certification bodies, and the corresponding logos are added, consumers can purchase with confidence.
How to choose an air purifier?
Understand core technologies
Understand the corresponding technical characteristics and advantages and disadvantages of air purifiers, so that consumers can purchase products that suit their needs. Different purification process combinations have slightly different purification effects and are also related to the maintenance of after-sales equipment, filter replacement and clean.
Clear purchase requirements
In the face of a wide range of goods, consumers are easy to pick the eye, so on the basis of a basic understanding of the product, consumers should be clear about their own consumer demand, or pay attention to the price, or focus on the purification function, or with the decoration style Wait, the product selected after the purpose is more suitable for yourself.
For example, indoor particulate matter pollution is mainly focused on particulate matter, PM2.5 and other products with strong purification ability; indoor new decoration focuses on products with strong purification ability of volatile organic compounds such as formaldehyde and toluene; air purifiers used in bedrooms focus on noise Level, mute effect, etc.; high-voltage electrostatic precipitator products do not need to replace the filter, but may produce ozone, carefully selected for odor-sensitive consumers.
The effective working area of the indoor air purifying device is preferably equal to the area of your environment. Otherwise, the area of the working area is too small to be ideal for purifying the environment. If it is too large, it will inevitably cause energy waste and sometimes even It will cause excessive accumulation of certain derivatives and affect indoor air quality. Therefore, the consumer selects the air purifier of the corresponding specification according to the room area used, and can refer to the following formula:
Where: S is the room area, the unit is m2;
Q is the amount of clean air (CADR value) for removing particulate matter in m3/h.
Attention to performance indicators
Each air purifier will have a nameplate that clearly states the technical parameters of the product and the national standards that are clearly indicated. For air purifiers of the same size, different parameters represent performance differences. For example, the national standard GB/T 18801-2015 divides the purification energy efficiency into high-efficiency and qualified grades. In the case of the same power consumption, the high-efficiency grade can output more clean air and can remove more formaldehyde. That is to say, the higher the energy efficiency level, the more electricity savings.
Pay attention to product experience
In addition to technical indicators, we should also consider whether the product design is user-friendly, the size of the noise and the operation is simple and convenient, noise. Some professional air purifiers have fully intelligent central control systems, such as intelligent real-time monitoring of temperature and humidity, automatic mode, intelligent timing, filter update smart tips, etc., as well as smart child lock design and intelligent power-off function, enabling consumers to Get more satisfying user experience.
Look for a certification mark
China Quality Certification Center (CQC) has launched a series of targeted certification projects for air purifier products. It is tested according to national standards, combined with the verification of product quality assurance and product consistency, and third-party certification. For the certified products that meet the standard requirements, the certification mark is attached to the market, which is convenient for consumers to purchase.
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