It is generally known that all equipment, pipes, cylinders and tools in contact with oxygen shall not be stained with grease or other inflammable. It is also known that oxygen and combustible gas can form explosive mixed gas. However, people often ignore such oxidizing gases as chlorine, fluorine and nitrogen oxides.

For example, when chlorine and methane and other hydrocarbon gases are mixed, they can react violently or even explode under sunlight; When chlorine and hydrogen and other combustible gases are mixed, they will burn and explode when exposed to sunlight or light. Therefore, oxidizing gases cannot be ignored.