1. Clarify the purpose of the test and select the instrument category
In short, the detection of harmful gases has two purposes, one is to detect explosions, and the other is to detect poisons. The so-called explosion detection is to detect the combustible gas content in dangerous places and alarm if it exceeds the standard to avoid explosion accidents; the poison detection is to detect the toxic gas content in dangerous places and alarm if it exceeds the standard to avoid poisoning of workers. The explosion detection range is 0~100% LEL, and the poison detection range is 0~tens (or hundreds) ppm. There is a big difference between the two.

There are three types of harmful gases in hazardous places. First, they are non-toxic (or low-toxic) and flammable. Second, they are non-flammable and toxic. Third, they are flammable and toxic. The first two situations are easy to determine, one is to test for explosion, the other is to test for poison, and the third situation is to test for poison if someone is exposed, and to test for explosion if no one is exposed.

2. Clarify the detection purpose and select the type of instrument (portable or fixed)
Fixed detection alarms are used for long-term leak detection in production or storage posts; portable (or pocket-sized) instruments are used for other inspections, such as maintenance detection, emergency detection, entry detection and patrol detection.

3. Clarify the detection objects and select the best instrument model


◆ The manufacturer is honest, has good reputation, and the quality of production is guaranteed. It has an explosion-proof certificate issued by the technical supervision department.