Carbon dioxide sensor selection guide

 As an instrument for detecting the concentration of carbon dioxide, the carbon dioxide sensor has a wide range of applications in the living environment, plant cultivation, cultural relics, and file protection. You need to choose different sensors according to different scenarios. Here is a guide for reference.

Price

People often say that you get what you pay for. But if you choose the carbon dioxide sensor with the thought of "you should buy expensive, quality can be guaranteed", then you may be at a disadvantage.

The price factor is of course an important reference item when choosing a sensor, but the specifics still depend on the application. You can choose within the range of your own product needs, and you don't need to pursue the so-called "expensive".

Range

The range of the sensor is also an important indicator when choosing, but if you pursue a large range too much, it is completely unnecessary. There is a difference between the range selection and the price problem, that is, it is suitable for own products.

In a natural environment, the normal content of carbon dioxide in the air is 0.04% (400 ppm), and sometimes reaches 500 ppm in large cities. When there are no people indoors, the carbon dioxide concentration is generally around 500 to 700 ppm.

Generally speaking, when the indoor carbon dioxide content is above 5000ppm, the human body functions will be seriously confused, causing people to lose consciousness and confusion. To detect the concentration of carbon dioxide in the home environment, the sensor range of 0-5000ppm is sufficient. In public places, classrooms and other densely populated environments, the sensor range of 0-50000ppm is also ok~

When selecting, as long as the sensor range covers the carbon dioxide concentration under the extreme conditions of the use environment, it is not necessary to pursue a large range too much.

Principle

There are two main types of CO2 sensors commonly used in the market, one is solid electrolyte, and the other is infrared. Among them, the principle of solid electrolyte sensor refers to the formation of electromotive force when gas-sensitive materials pass through the gas, and the electromotive force is measured to measure the gas concentration. Due to the high conductivity of this sensor and good selection characteristics, it is widely used. The principle of the infrared carbon dioxide sensor is based on the absorption of CO2 to a specific band of infrared radiation, so that the radiant energy passing through the measurement chamber is weakened, and the degree of weakening depends on the CO2 content in the measured CO2 gas.

Signal output

Currently, sensor signal output methods include serial port, analog, GPRS, Ethernet, WiFi and other signal output methods. Different signal output methods have different installation methods. The signal output should not be simply divided according to the advantages and disadvantages, but depends on the environmental requirements of the design product scheme.

Measurement accuracy

Accuracy has always been an important performance index of the sensor, and it is an important link related to the measurement accuracy of the entire measurement system. The higher the accuracy of the sensor, the more expensive it is. Therefore, the accuracy of the sensor only needs to meet the accuracy requirements of the entire measurement system, and it is not necessary to select too high. In this way, a cheaper and simple carbon dioxide sensor can be selected among many sensors that meet the same measurement purpose.

Preheat time

Different types of sensors that detect different gases require different warm-up times. Some require a few minutes, and some require just a few seconds. The light source and detector in the infrared carbon dioxide sensor need to be energized to reach the best state, in order to read the accurate value. Preheating is for the stability and accuracy of the sensor, and has nothing to do with poor product performance.