Explosion is the sudden transformation of a substance from one state to another through physical or chemical changes, and the release of enormous energy. The energy released at a rapid speed will cause violent impacts and damage to surrounding objects.

The three necessary conditions for an explosion are:

1) Explosive substances: Substances that can react with oxygen (air), including gases, liquids, and solids. (Gas: hydrogen, acetylene, methane, etc.; Liquid: alcohol, gasoline; Solid: dust, fiber dust, etc.) 2) Oxygen: air. 3) Sources of ignition: including open flames, electrical sparks, mechanical sparks, electrostatic sparks, high temperatures, chemical reactions, light energy, etc.

Why explosion-proof

Explosive substances: Many production sites produce certain combustible substances. About two-thirds of the underground coal mines contain explosive substances; In the chemical industry, over 80% of production workshop areas contain explosive substances. Oxygen: Oxygen in the air is ubiquitous. Ignite source: Electrical instruments are widely used in the production process, and various frictional sparks, mechanical wear sparks, electrostatic sparks, high temperatures, etc. are inevitable, especially when instrument and electrical failures occur.

Objectively, many industrial sites meet explosion conditions. When the mixture concentration of explosive substances and oxygen is within the explosive limit range, if there is an explosive source, an explosion will occur. Therefore, it is necessary to adopt explosion-proof measures.

The principle of instrument explosion-proof

Classification of hazardous areas:

Chinese standard North American standard for defining explosive substance regions

Gas (Class I) in normal conditions, explosive gas mixtures exist continuously or for a long time in Zone 0 Div.1

Zone 1 where explosive gas mixtures may occur under normal circumstances

Explosive gas mixtures are unlikely to occur under normal circumstances, only occasionally or for a short period of time in areas 2 Div.2

Dust or fiber (Class II/III) - Under normal circumstances, explosive dust or combustible fiber mixtures with air may occur continuously, frequently, or for a long time in Zone 10 Div.1

Under normal circumstances, explosive dust or mixtures of combustible fibers and air cannot occur, but only in areas with occasional or short-term occurrences under abnormal circumstances, Div.2 in Zone 11