According to the detection principle, the online celebrity formaldehyde detectors on the market can be divided into two categories: semiconductor detection and electrochemical detection.
The former uses the conductivity change of semiconductor materials to detect the concentration of gas, so the detection results are rough, but the advantage is that the price is very cheap, so it is favored by everyone.
The latter allows formaldehyde gas to enter the instrument through the selectively permeable membrane, thus contacting the electrolyte inside the instrument. According to the diffusion speed of formaldehyde in electrolyte, the indoor formaldehyde concentration can be measured by electrochemical formaldehyde tester. It must be said that the test accuracy of electrochemical test method is much higher than that of semiconductor test method. However, the electrolyte in the instrument will be consumed continuously with time, so its accuracy is also declining. In addition, the electrochemical test method is easily interfered by some gases, such as kitchen fume and gas produced by cigarettes.
To sum up, it is very unreliable to measure indoor formaldehyde concentration only by 20-300 formaldehyde tester. However, you can test through some professional channels.
At present, some air testing companies with CMA qualification are undoubtedly the authoritative organizations for formaldehyde gas detection. As for the price, it must be more than 300. Its price is around 300-500 yuan /20 square meters. This price is a lot more expensive, but for the sake of health and accuracy, why not?