Since the outbreak of the new coronavirus pneumonia, fresh air products have become one of the most concerned products of the people. In addition to ventilation, the most important function of the fresh air system is to filter pollutants in the air, so the filter of the fresh air system is the most important part of the entire system. The quality of the filter directly affects the quality of indoor air.

According to the grade, principle and material, the filter type of the fresh air system can be divided as follows:

According to the filter rating

The general fresh air system filter can be divided into three levels, namely, the initial effect filter, the medium effect filter and the high efficiency filter.

1. Initial effect filter: filter outdoor large particles of dust and bugs and other substances.

2. Medium effect filter: filter outdoor pollen and other small particles.

3. High efficiency filter: that is, HEPA, filter that meets HEPA standard.

Filter most of the dust above 0.3 micron. Many fresh air systems claim that the filtration efficiency is more than 99%, which is actually the test result after filtering several times. When you examine the filtering effect of the product, be sure to polish your eyes.

In the fresh air system, the initial effect, medium effect and high efficiency filter are generally not used alone, but two or three kinds of combined use. A fresh air system equipped with more than two layers of filters can achieve a better air filtration effect.

According to the filter principle

At present, the common filtration principle is divided into two kinds, one is the physical filtration method, the other is the electrostatic filtration method.

1. Physical filtration: Different levels of filtration materials are common from G1 to H13, the higher the level, the greater the wind resistance, the more thorough the filtration, and the more expensive the price.

2. Electrostatic dust collection: PM2.5 filtration effect is good, small wind resistance, do not need to replace the filter frequently. The disadvantage is that it is inevitable to produce ozone, and ozone is harmful to the body when it reaches a certain level. Therefore, the requirements of electrostatic dust collection for ozone production must be strict, and products that meet national standards and pass the quality must be selected.

Among the fresh air system, the most used is the physical filtration method, and the filter needs to be replaced regularly, otherwise it can not achieve good filtration effect. Electrostatic dust collection method is in the popularization stage, some large manufacturers have developed or are developing related functions, it is expected that this filter method will be widely used in recent years.

Sort by filter material

Non-woven fabric filter: the scientific name polyester fiber, commonly known as non-woven fabric, non-woven fabric has the use of widespread, technical maturity, good stability and other technical characteristics, is China's current initial, medium efficiency plate, bag filter typical filter material. Compared with other filter materials of the same grade, it has the advantages of stable quality, large dust tolerance, strong moisture resistance, long service life, economic and durable. Non-woven fabrics are also the earliest application of filter materials, in recent years due to the continuous progress of technology, the emergence of composite non-woven fabrics greatly improve the image of cheap low-grade non-woven fabrics, in terms of efficiency has been able to achieve sub-efficiency.

Glass fiber filter: glass fiber filter is mainly made of glass fiber of different thickness and length by special processing technology. Glass fiber with its stable performance, high temperature resistance, high efficiency, large capacity, long service life and so on. And in some special circumstances, only wave lines can do the job. Widely used in the general ventilation system of the initial effect filter, high temperature filter and high efficiency filter.

Synthetic fiber filter: in the general filtration environment can fully replace non-woven fabrics and glass fibers, covering a full range of coarse, medium and efficient filtration products, is an emerging filtration material, but also the main development direction of future filtration materials. Compared with other filter materials of the same level, it has the advantages of low resistance, light weight, large capacity, environmental protection (can be incinerated) and moderate price.

Activated carbon filter: has the efficient adsorption performance of activated carbon, can be used for air purification, removal of volatile organic compounds formaldehyde, toluene, hydrogen sulfide, chlorobenzene and air pollutants. The activated carbon filter adopts aluminum honeycomb, plastic honeycomb and paper honeycomb with through-hole structure as carrier. Compared with the traditional activated carbon filter, it has better gas dynamic performance, small volume density, large surface area, high adsorption efficiency and small wind resistance coefficient. The cellular activated carbon filter is made of powdered activated carbon attached to polyurethane foam, and its carbon content is about 35%-50%. The air resistance is small, the energy consumption is low, can deodorize, remove odor and purify the environment under a certain air volume, and has a good purification effect. In use. Generally, it must be combined with the use of independent primary and medium efficiency filters.

In general, non-woven fabric filter and glass fiber filter are mostly used as primary filter, synthetic fiber filter, activated carbon filter, nano silver filter and photocatalyst filter are mostly used as medium effect and high efficiency filter. Better quality fresh air systems will be equipped with more than two layers of filters to efficiently filter air pollutants.