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Why buy haze meter when using air purifier?

Update: 2019-11-14 17:03 Source: LUFTMY

Now many air purifiers on the market have built-in haze meters, that is, PM2.5 detector. Speaking of this, are you confused? Someone else's air purifier clearly has built-in haze meters. Why should we buy a haze meter alone?

Air purifier
Air purifier

I don't know if you find that the built-in Haze Meter of the air purifier you bought doesn't display specific values, but uses different colors of lights to represent the air quality.

If the air purifier is equipped with a haze meter, it is more convenient to test whether the air purifier is in use?

1. How to measure PM2.5

Friends who have used the haze meter will find that the reading of our detector is different from the data published by the Environmental Protection Bureau. This is because the measurement methods are different. The Environmental Protection Bureau directly weighs the particles collected in one hour, and then takes the average value. Generally, the average value of the previous hour will be published after 20 minutes.

Haze table with built-in PM2.5 sensor
Haze table with built-in PM2.5 sensor

The detector in our hand uses the light scattering counting method. When the light hits the suspended particles, the scattered light will be generated. The scattering light intensity of the particles is directly proportional to its concentration. By measuring the scattering light intensity and using the existing conversion model, the number concentration of the particles can be obtained. The manufacturer then converts the number concentration of the particles into the mass concentration according to its own algorithm. The algorithms of different manufacturers are different, so the values of different haze tables in the same room will be different.

2. How to choose haze watch?

There are two kinds of light scattering method: laser and infrared. The accuracy of laser haze detector is higher than that of infrared haze detector. This is because infrared haze detector uses infrared sensor and laser haze detector uses laser sensor. The accuracy of the infrared sensor itself is not high, and engineers need to measure, compare and calibrate repeatedly, and then fit out a curve, and finally it is still inaccurate. The accuracy of laser sensor is high, and it does not need to be calibrated repeatedly, and its life is longer than that of infrared sensor, up to tens of thousands of hours.

In terms of price, the price of infrared haze detector is lower, below 100 yuan. If you buy modular products on Taobao, the price will be lower. The lowest cost of laser haze detector is 200 yuan, because a single laser sensor is about 100 yuan, plus peripheral circuits and molds, the lowest cost is 150 yuan.

3. Is the haze table reliable?

Compared with those professional measuring equipment, the accuracy of these haze meters used in our life is slightly worse, but this does not mean that haze meters are not available, but that when you use haze meters to monitor indoor air quality, you can see the relative number rather than the absolute number. For example, after turning on the purifier for a period of time, the haze meter shows a decrease in the number, which indicates that the air quality has improved, but the PM2.5 concentration figure itself is not necessarily very accurate.

Haze table detects pollution sources
Haze table detects pollution sources

PM2.5 particle sensor HPD05 uses the principle of optical scattering to obtain the particle concentration, and measures the dust concentration within the detection range through the conversion of optical path and circuit. PM2.5 particle sensor hpd05 has the characteristics of small volume, high precision, low power consumption, short response time and stable operation under high dust concentration. This PM2.5 particle sensor can be used in air purifier, haze meter, etc.

HPD05 Infrared PM2.5 dust sensor
HPD05 Infrared PM2.5 dust sensor
 

TAGlaser dust pm2.5 sensor PM2.5 particle sensor digital laser dust sensor laser particle concentration sensor