Principle of Air Quality Monitor

Before we use an instrument, it is very necessary to understand how it works, because its principle determines how it is used and some of its features. Air quality detector is a kind of instrument used to determine the quality of gas, its response speed is relatively fast, can help us know the quality of air in a certain environment in a timely manner. Since some users do not particularly understand the working principle of the air quality detector, the following is a brief introduction to you.


Air quality sensor is relatively common in our daily life, it can detect formaldehyde, PM2.5, TVOC and temperature and humidity and other parameters in real time. Through the sensor on the gas concentration to play a role in detecting, can accurately measure the size of the concentration of pollutant gases, and quickly calculate the air quality index AQI, if the concentration of the current environment exceeds the standard will be immediately after the alarm.

 

The working principle of the air quality sensor is to use formaldehyde sensors, PM2.5 sensors, TVOC sensors and temperature and humidity sensors and other devices, the gas will be inhaled into the instrument through the operational amplifiers will be the sensor to amplify the weak signals captured, and then remove some noise interference, and then after processing through a special technology, you can display the measurement data on the screen in real time.

 

From the above, it can be learned that the working principle of the air quality sensor is mainly realized through the sensor, and different sensors should be used when detecting different types of gases, so as to ensure that the measurement results obtained are accurate. Because the air quality detector has good detection performance, so it is also a wide range of applications.

 

Air Tester Temperature and Humidity Measurement Method

1. Dual-pressure method, dual-temperature method

Dual-pressure method, dual-temperature method is based on the thermodynamic P, V, T equilibrium principle, the equilibrium time is longer, the shunt method is based on the precise mixing of absolute moisture and absolute dry air. Due to the use of modern measurement and control means, these devices can be made quite precise, but because of the complexity of the equipment, expensive, time-consuming and labor-intensive operation, mainly as a standard measurement of the use of the measurement accuracy of up to ± 2% RH or more.

 

2. Saturated Salt Method

Static method of saturated salt method, is the most common method of humidity measurement, simple and easy to implement. However, the saturated salt method of liquid, gas and two-phase equilibrium requirements are very strict, the stability of the ambient temperature requirements are high. Use up the requirement to wait a long time to equilibrate, the low humidity point requires longer. Especially when the difference between indoor humidity and humidity inside the bottle is large, every time you open it, you need to equilibrate for 6~8 hours.

 

3. Dew Point Method

Dew point method is to measure the temperature of wet air when it reaches saturation, is a direct result of thermodynamics, high accuracy, wide measurement range. Measurement of precision dew-point meter accuracy of up to ± 0.2 ℃ or even higher. But with modern optical - electrical principle of cold mirror dew point meter is expensive, often and standard humidity generator supporting the use.

 

4. Wet and Dry Bulb Method

Wet and dry bulb method, which was invented in the 18th century to measure humidity. It has a long history and is most commonly used. Dry and wet bulb method is an indirect method, it uses the dry and wet bulb equation to convert the humidity value, and this equation is conditional: that is, in the wet bulb near the wind speed must reach 2.5m/s or more. Commonly used dry and wet bulb thermometer to simplify this condition, so its accuracy is only 5-7% RH, dry and wet bulb does not belong to the static method, do not simply think that as long as to improve the accuracy of the measurement of the two thermometers is the same as improving the accuracy of the measurement of the hygrometer.


5. Electronic Humidity Sensor Method

Electronic humidity sensor products and humidity measurement belongs to the 90's industry, domestic and foreign in the field of humidity sensor research and development has made great progress. Humidity sensor is from a simple moisture-sensitive components to integrated, intelligent, multi-parameter detection of the direction of rapid development for the development of a new generation of humidity measurement and control systems to create favorable conditions, but also humidity measurement technology to a new level.

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