Gas detectors are usually used to detect toxic, harmful or flammable gases. Toxic gas detectors are generally used in biochemical, pharmaceutical, construction and other industries, while combustible gas detectors are often used in coal mines, petroleum, chemical, fuel and other industries. With the rapid development of the industry, the monitoring of gas in the environment is essential, so how should we choose a gas detector? At present, there are portable gas detectors and fixed gas detectors provided by manufacturers and supplies. These two types of gas detectors are divided into 1 in 1, 2 in 1, 4 in 1 and other specifications, and these products with different specifications have different application functions for gases. The detection standards for different industries and occasions are different, and the detection standards for different gases are also different.