Application of quality detection and sensors in indoor air pollution

Shandong Liaocheng East Ajinhua Iron and Steel Company understands that from the perspective of technological development, according to the principle of using sensors, common gas detection instruments and meters have their own applicable gas and application fields, and new technologies and new products are becoming the mainstream of gas detection instruments in the future. .

1. The importance of air to people

Shandong Liaocheng East Ajinhua Iron and Steel Company knows that people can't live without oxygen and get oxygen by inhaling air. An adult needs to inhale up to 6,500 liters of air every day to get enough oxygen, so the polluted air has a direct impact on human health. People spend more than 90% of their time indoors. It can be seen that the impact of indoor air quality on people is even more important.

2. Indoor environmental pollution background

In Shandong Liaocheng East Ajinhua Iron and Steel Co., Ltd., it seems that human beings are facing "smoke pollution" and "photochemical smog pollution", and then there is the third environmental pollution mainly caused by "indoor air pollution". American experts found that there are more than 500 kinds of volatile organic compounds in indoor air, including more than 20 kinds of carcinogens and more than 200 kinds of pathogenic viruses. The main hazards are: radon, formaldehyde, benzene, ammonia and esters, trichloroethylene, etc. A large number of shocking facts confirm that indoor air pollution has become a "stealth killer" that endangers human health, and has become a common concern of countries all over the world. According to statistics, nearly half of the world's people are in indoor air pollution. Indoor environmental pollution has caused 35.7% of respiratory diseases, 22% of chronic lung diseases and 15% of bronchitis, bronchitis and lung cancer.

3. Several ideas on developing indoor air quality services

1. Start to investigate the basic situation of air quality in domestic homes and offices.

2. Understand and start to introduce indoor air quality testing equipment.

3. For large-scale publicity activities, first, the meteorological department and the environmental protection department should jointly establish a management mechanism for indoor air quality problems.

4. Specially investigate and research the international environmental protection department's regulations, technical standards, indoor pollution measurement methods, and measuring instruments.

Fourth, the powerful weapon of the air detector-sensor

Shandong Liaocheng East Ajinhua Iron and Steel Company: Testing technology is an indispensable and important technical means for people to understand and transform the world. Sensors are an important tool for the development, acquisition, transmission and processing of information resources in scientific experiments and industrial production. Here are six sensors that play an important role in air quality detection.

1. Metal oxide semiconductor sensor. The metal oxide semiconductor sensor uses the adsorption of the measured gas to change the conductivity of the semiconductor, and the alarm circuit is excited by the comparison of the current change. Because semiconductor sensors are greatly affected by the environment during measurement, the output line shape is unstable. Metal oxide semiconductor sensors, because of their sensitive response, are currently widely used in the field of measuring gas micro-leakage.

2. Catalytic combustion sensor. The principle of catalytic combustion sensor is one of the most widely used principles for detecting combustible gas. It has the characteristics of good output signal line shape, reliable index, low price, and no cross interference with other non-combustible gas. The catalytic combustion sensor uses the Wheatstone bridge principle.The induction resistance and the combustible gas in the environment are flameless.It is the temperature that changes the resistance of the induction resistance, breaking the balance of the bridge, so that it outputs a stable current signal, and then passes The amplification, stabilization and processing of the later circuit finally show reliable values.

3. Constant potential electrolytic sensor. Constant potential electrolytic sensors are currently the most widely used technology in the field of poison detection. In this regard, foreign technology is leading, so most of these sensors rely on imports. The structure of a constant potential electrolytic gas sensor: in a cylindrical cell made of plastic, the working electrode, the counter electrode and the reference electrode are installed, and the electrolyte is filled between the electrodes, and the diaphragm made of porous tetrafluoroethylene is in Top package. The connection of the preamplifier and the sensor electrode applies a certain potential between the electrodes, so that the sensor is in a working state. The working electrode in the electrolyte with the gas undergoes oxidation or reduction reaction, and the reduction or oxidation reaction occurs at the counter electrode, the equilibrium potential of the electrode changes, and the change value is proportional to the gas concentration.

4. Galvanic battery-type oxygen sensor. The structure of the galvanic battery-type oxygen sensor: a plastic container is equipped with a permeable polytetrafluoroethylene membrane with a thickness of 10-30 μm that has good oxygen permeability, and precious metals (platinum, gold, silver Etc.) A cathode electrode, forming an anode (a metal with a large ionization tendency such as lead or cadmium) on the inside of the other side of the container or an empty part of the container. Use potassium hydroxide. When oxygen passes through the electrolyte, a redox reaction occurs at the cathode and anode, which ionizes the anode metal and releases electrons. The current is proportional to the amount of oxygen. Because the anode metal is consumed throughout the reaction, the sensor needs to be replaced regularly. At present, domestic technology has become increasingly mature, and such sensors can be fully domesticated.

5. Infrared sensor. Infrared sensors use the absorption principle of various elements to a specific wavelength, have good anti-toxicity, and are sensitive to reaction, and they can react to most hydrocarbons. But the structure is complex and the cost is high.

6. PID photoionization gas sensor. The PID is composed of the main parts of the ultraviolet lamp light source and the ion chamber.The ion chamber has positive and negative electrodes to form an electric field. Under the irradiation of the ultraviolet lamp, the gas to be measured is ionized to generate positive and negative ions, and a current is formed between the electrodes.The output is amplified. signal. PID has the advantages of high sensitivity, no poisoning problems, safety and reliability.

V. In-depth analysis of the development status of the gas detection instrument industry

Shandong Liaocheng East Ajinhua Iron and Steel Company: In recent years, with the rapid development of China's economy, the instrumentation industry has also developed rapidly. Since 2004, the production and sales exceeded the 100 billion yuan mark for the first time, and the industry has entered the fast lane. The total output value exceeded 200 billion yuan; the total output value of the instrumentation industry reached 307.8 billion yuan in 2007, with a growth rate of up to 28.5%; according to the statistics of the Instrumentation Industry Association, the total output value of the instrumentation industry in the first half of 2008 reached 175.59 billion yuan, a year-on-year increase of 23.8 %, Of which the growth rate of analytical instruments and environmental monitoring instruments is as high as 32%.

The advancement of science and technology has provided conditions for the development of the gas detection instrumentation industry.The promotion of the market and government policies, the improvement of people's safety awareness, and the improvement of relevant laws and regulations are the core driving forces for the development of the gas detection industry. The industry is in a period of rapid industrial growth.

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