The ignition source, as a heat source providing combustion reactions, is the direct cause of inducing dust explosion accidents. In industrial production, there are various types of ignition sources around various process equipment or ancillary components. According to the relevant provisions of GB25285.1-2010 "Prevention and Protection of Explosive Atmospheres - Part 1: Basic Principles and Methods", the types of ignition sources in industrial explosive hazardous environments can be divided into 13 categories. According to incomplete statistics, the ignition methods that cause dust explosions mainly include impact or friction, electrostatic sparks, fusion or melting sparks, spontaneous sparks, open flames, metal overheating, and electrical sparks according to the frequency of accidents. Overall, the common ignition sources in explosive dust environments are:

Open flame

Open flames are an important ignition source for industrial fire and explosion accidents, and smoking, industrial hot work (such as gas cutting and welding), heating furnaces, etc. are all effective ignition sources for explosive hazardous environments. Usually, in safety management, enterprises should strictly prohibit the presence of open flame ignition sources in explosive hazardous areas, and establish a sound hot work system. If open flame operation is necessary, it should be strictly carried out in accordance with the hot work system.

High temperature objects

The hot surface of high-temperature objects is a potential ignition source for explosive hazardous environments, and can be divided into two categories: electrical equipment hot surface and non electrical equipment hot surface. In industrial production, heating equipment, heating equipment, motors/lamps, etc. are prone to become high-temperature objects, and explosion-proof treatment should be carried out in accordance with the relevant requirements of series standards such as GB3836 and GB12476. Mechanical equipment such as internal combustion engines, gearboxes, bearings, and other mechanical components or components are prone to forming high-temperature hot surfaces under normal or faulty conditions. In industrial safety production, ignition hazard assessment and detection should be carried out in accordance with GB25286 and related series standards.

Electrical sparks

Electrical spark is a potential ignition source carried by electrical equipment itself, which is a breakdown discharge between electrodes. Usually, electrical sparks are easily generated when electrical circuits are disconnected or short circuited, electrical equipment is braked, or electrical equipment is overloaded.

electrostatic discharge

According to the form of static electricity generation, static electricity can be divided into various forms of electrification, such as contact friction separation electrification, electrostatic induction electrification, and electromagnetic induction electrification; According to the properties of charged bodies, they can be further divided into solid, liquid, gas, powder, and human charged bodies. In explosive dust environments, various non-metallic components or non-metallic parts of components are prone to generate frictional static electricity, and various electromagnetic induction causes metal components to easily form induced static electricity. As an important participant in explosive dust environments, the human body itself is an important source of static electricity generation. Therefore, in dust explosion hazardous environments, various types of static electricity are widely present and effective measures should be taken to avoid them.

Impact and friction

The impact and friction between mechanical equipment or components are also important ignition sources for combustible dust environments. During the process of impact and friction between metal components, it is highly likely to generate metal sparks or friction with high-temperature hot surfaces, thereby igniting explosive hazardous environments. Therefore, all types of mechanical equipment or components used in explosive hazardous areas should be evaluated for their ignition hazard, the risk of the equipment becoming an effective ignition source should be analyzed, and measures should be taken to avoid it, ensuring the safe use of mechanical equipment in explosive hazardous environments.

chemical reaction

Chemical reactions, especially self heating reactions, are potential ignition sources for explosive hazardous environments, such as aluminum iron reactions, oxidation combustion, etc. A large amount of freely accumulated dust, such as coal mines, flour, and corn starch in grain warehouses, often spontaneously ignites and catches fire due to the accumulation of dust.

thunder

Lightning is one of the greatest threats to explosive dust environments in nature. The huge discharge current generated during lightning discharge has a great destructive power and is also prone to dust explosion accidents. Therefore, factories (buildings) in workplaces with dust explosion hazards must be equipped with lightning protection systems in accordance with the "Code for Design of Lightning Protection of Buildings" (GB50057-2010) and can be grounded.