An 'air purifier that you can make yourself in just 30 seconds' that simply attaches a filter to an electric fan is more effective than commercial products.



Air purifiers

remove various particulate matter such as pollen and soot in the air, but commercially available air purifiers cost tens of thousands of yen. Therefore, we have released the results of an experiment on how effective the person who made the 'air purifier, which is simply a filter attached to a fan' actually exerts.

Experiments on a $ 50 DIY air purifier you can make in 30s
https://dynomight.net/2020/12/15/some-real-data-on-a-DIY-box-fan-air-purifier/

Contaminated air is bad for your health, but not everyone can buy an expensive air purifier. The author, dynomight (@ dynomight7) , wondered, 'Why do I have to pay $ 100- $ 300 (¥ 11,000-33,000) for a big box that just contains a fan and a filter?' I decided to make a DIY air purifier with a cheap fan and filter.

This is the DIY air purifier actually made by Mr. dynomight. Just attach a HEPA filter ($ 35 / about 3900 yen for 2 sheets) of length 32 cm x width 22 cm x thickness 5 cm to the exhalation side of a box-shaped square fan ($ 19 / about 2100 yen). , It took only 30 seconds to assemble. The size of the filter does not match the size of the box-shaped fan, and it is an air purifier full of handmade feeling that the part where the string is wound is wrinkled.



Mr. dynomight purchased an air purifier for 100 dollars (about 11,000 yen) for comparison, 'using a fan without a filter' 'using a commercially available air purifier' 'DIY air purifier' I investigated how much the air purification capacity differs depending on the 'used state'. In addition, the commercially available air purifier uses a HEPA filter with a length of 25 cm, a width of 12 cm, and a thickness of 4 cm, and the replacement price was 25 dollars (about 2800 yen).

To experiment with purification capacity, dynomight decided to burn incense cut to the length of a credit card and generate smoke indoors. Then, using a $ 100 atmospheric monitor borrowed from a friend, he measured the fine particulate matter (PM2.5) contained per cubic meter. According to the United States Environmental Protection Agency, PM2.5 per cubic meter should average 12 micrograms or less per cubic meter and 35 micrograms or less per day on average, which is within the range of 15 micrograms or less in general developed countries. that's right. However, cooking indoors can increase the amount of PM2.5 at once, sometimes reaching hundreds of micrograms, dynomight said.

The experimental environment of Mr. dynomight is as follows. An air monitor and a stopwatch are placed in a small room with a volume of 8 cubic meters, and while taking a picture of the situation with a tablet, incense is burned and an air purifier is operated. In addition, in order to prevent the wind of the air purifier from affecting the amount of smoke, it seems that a wall was sandwiched between the air purifier and the incense to prevent the wind from hitting it.



This is a graph of the results of experiments conducted with 'a state using a fan without a filter', 'a state using a commercially available air purifier', and 'a state using a DIY air purifier'. The vertical axis represents the amount of PM2.5 (microgram / 1 cubic meter), the horizontal axis represents the time (minutes), the 'state using a fan without a filter' is the blue dotted line, and 'using a commercially available air purifier'. The 'state' is shown by the green line, and the 'state using the DIY air purifier' is shown by the orange line. The result is that DIY air purifiers are faster than commercial air purifiers and remove PM2.5 in the air.



This is the log-log graph showing the purification ability. The PM2.5 concentration in the air falls below the '12 micrograms / cubic meter' recommended by the United States Environmental Protection Agency, about 15 minutes after the start of the experiment with a DIY air purifier, and about 25 minutes with a commercially available air purifier. It is later.



Dynomight also conducted a similar experiment in a room of about 100 cubic meters. This time, because of the relatively large space, no wall was installed between the incense and the air purifier, and the monitor, air purifier, and incense were separated by 1 meter each.



The results of the experiment are as follows. Although the difference is smaller than before, the result is that the DIY air purifier cleans the air faster than the commercially available air purifier.



The log-log graph looks like this.



In addition, Mr. dinomight thought that 'it may be possible to improve the performance of the DIY air purifier by blocking the leakage of the filter', 'The DIY air purifier with tape between the fan and the filter' as follows. I heard that I also made it. However, the performance was about the same as a normal DIY air purifier.



A series of experiments suggested that DIY air purifiers have excellent performance. In addition, because the area of the filter used in the DIY air purifier is large, it seems that the frequency of filter replacement may be less than that of a commercially available air purifier.

On the other hand, the power consumption of a commercially available air purifier is about 30 to 45 W, but the power consumption of a general box-shaped fan is 55 W, and the commercially available air purifier is superior in terms of power consumption. Said dynomight. He also said that many air purifiers have the ability to operate only when the surrounding air becomes dirty, which will consume even less power than DIY air purifiers.

in Note,   Hardware, Posted by log1h_ik