Explosion proof certification is actually a necessary test that most electrical products must pass and obtain certification certificates for. This is not only a guarantee of product quality promotion, but also can make customers feel more at ease when using it. The country also has a strict set of standards for explosion-proof certification. Below is an interpretation of the explosion-proof level classification standards brought by Zhongnuo Testing.
The concept of explosion prevention
The occurrence of an explosion requires certain prerequisites
1. Presence of explosive substances (combustibles)
2. It forms an explosive mixture within a certain space, with a concentration within the explosive limit range of the gas; (Adequate oxygen)
3. There is an ignition source, and its energy must be greater than the minimum ignition energy of the explosive mixture (reaching the ignition point)
Only when these three factors coexist in a certain area can an explosion occur, which is the so-called explosion triangle principle. And what we need to do is to control one or more of these three conditions. The oxygen and explosive substances in explosive environments objectively exist, so what we need to control is the objects (and detonation sources) working in explosive hazardous environments, and this operation is called explosion prevention.
The significance of explosion prevention
Explosive substances: Many production sites produce certain flammable 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. Ignition 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 instruments and electrical components fail.
Objectively, many industrial sites meet explosive conditions. When the concentration of explosive substances mixed with oxygen is within the explosive limit range, if there is an explosion source, an explosion will occur. Therefore, it is necessary to adopt explosion-proof measures.
Explosion proof grade description
IA level: Electrical equipment that cannot ignite explosive gas mixtures during normal operation, one fault, and two faults.
During normal operation, the safety factor is 2.0;
When there is a malfunction, the safety factor is 1.5;
When there are two faults, the safety factor is 1.0.
Note: Contact points with sparks must be equipped with explosion-proof enclosures, airtight enclosures, or double the safety factor.
IB level: Electrical equipment that cannot ignite explosive gas mixtures during normal operation and a fault.
During normal operation, the safety factor is 2.0;
When there is a malfunction, the safety factor is 1.5. During normal operation, contacts with sparks must be protected by explosion-proof or airtight enclosures, and there should be measures for fault self display. The safety factor for one fault is 1.0.
Classification of hazards in hazardous areas
Applicability of explosion-proof methods to hazardous areas
Classification of Explosive Hazardous Gases
According to the minimum spark energy that may ignite, explosive gases are classified into four hazard levels in China, Europe, and most countries and regions around the world, as shown in the table below:
The United States and Canada first classified explosive objects scattered in the air into three classes: Class I gases and vapors; CLASS II dust; CLASS III fiber Then divide the gas and dust into groups:
Classification of gas temperature groups
Explosion proof mark
The meaning of Ex ia Ⅱ C T4:
Definition of safety parameters for safety barriers
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