This article aims to help you understand the working principle of air purifier and choose the right air purifier.

Working principle

The principle of the air purifier is very simple, that is to put a filter screen in front of the fan, the fan runs to extract air, the air passes through the filter screen to leave pollutants, and then discharges high-quality air.

Through the principle, we can see that the most important thing of the air purifier is the amount of air extracted by the filter and the fan. The filter represents its purification capacity, and the amount of air extracted by the fan represents the purification efficiency.

Purification efficiency

The purification efficiency is determined by the design of fan and air duct, because it is difficult for consumers to judge these two points, so the government requires businesses to mark CADR value.
The unit of CADR is m ³/ h. It refers to the volume of air that can be purified per unit time. In the same space, the higher the CADR value, the higher the purification efficiency of the air purifier.

So how to choose a suitable purifier?

There's a shopping formula,
Housing space X 5 = required CADR value.

For example: 
A room of 15 square meters, 2.5 meters in height, the room space is 37.5 m ³.
The space occupied by removing sofa and other objects can be calculated as 32m ³.
32 X 5=160
Then you need to buy an air purifier, its CADR is about 160m ³/ h.

Filter element of air purifier

Filter grade

There is no need to over pursue high-grade filter screen, because the air purifier is circulating filtration. Generally, the filter element of H11 is enough.

For instance:
The purification efficiency of H11 filter is 95%, and that of H12 filter is 99.5%. It seems that H12 is better, but if the air in the same space is repeatedly recycled and purified, the two effects are the same. In order to ensure the amount of air filtered per unit time, the fan speed of higher level purifier will be higher, and the noise will be higher.

Can the filter element filter formaldehyde?

Gaseous pollutants contain formaldehyde and other harmful gases, so the air purifier can filter formaldehyde.

The main function of air purifier is to remove PM2.5, and formaldehyde removal is only an additional function.

The most effective way to remove formaldehyde is ventilation.

Filter element type of air purifier

At present, the purification of gaseous pollutants by air purifier mainly depends on activated carbon adsorption.

At present, there are two kinds of activated carbon filter elements, and the use experience is very different.

The first type is carbon cloth. The composite filter screen is mainly made of carbon cloth. The activated carbon is broken into small pieces and combined with HEPA filter screen. In this way, the amount of activated carbon is small, but the unit area is large enough and the resistance is small. Therefore, the gas CADR value of this type of machine will be very high. However, this kind of carbon cloth will be sour after being used for a period of time, especially in the areas with high humidity.

The second type is columnar activated carbon particles. This kind of filter uses large particles of activated carbon. Although the gaseous CADR value may not be as high as that of carbon cloth, it has sufficient carbon, strong continuous adsorption capacity, and few acid problems.

Selection of air inlet and outlet

position of purifier

Now the mainstream air duct design has lower air inlet and upper air outlet, side air inlet and upper air outlet, side air inlet and side air outlet.

It is recommended to choose the lower air inlet and upper air outlet.  This kind of air duct design is the most reasonable. High CADR value can be ensured without high-power fan. The advantage is that the noise will be relatively reduced, and it can be placed at will. If it is side strong wind, it is also necessary to consider that there should be no shelter around.