{"id":32515,"date":"2024-01-02T15:02:54","date_gmt":"2024-01-02T13:02:54","guid":{"rendered":"https:\/\/obera.fr\/advice\/industrial-processes-and-prevention-of-explosion-or-fire-risks-using-industrial-dust-collectors\/"},"modified":"2025-04-15T10:20:01","modified_gmt":"2025-04-15T08:20:01","slug":"procedes-industriels-prevention-risques-explosion-depoussiereurs-industriels","status":"publish","type":"post","link":"https:\/\/obera.fr\/en\/our-tips\/procedes-industriels-prevention-risques-explosion-depoussiereurs-industriels\/","title":{"rendered":"Industrial processes and prevention of explosion or fire risks using industrial dust collectors"},"content":{"rendered":"\n

Many industrial systems<\/strong> use flammable powders or produce combustible dust. The operation of these production systems entails risks of fire and explosion. Risks deriving from the characteristics of the products and processes used. That’s why legislation on worker safety and environmental protection requires companies to install appropriate prevention and protection systems. The most common preventive measure is to control the suspension of particles and their concentration in the ambient air<\/strong> or in equipment. These are met by suction and filtration systems designed to remove dust from processes.<\/p>\n\n

How does a fire or explosion occur when using powdered products or emitting dust?<\/h2>\n\n
\"Explosion<\/figure>\n\n

Some industrial activities<\/strong>, particularly those involving the use of powders, disperse dust into the air, creating the risk of explosion or fire. They generate a cloud of combustible dust forming an explosive atmosphere<\/strong> (ATEX). ATEX will explode if it meets the right conditions. <\/p>\n\n

Another possibility: the dust cloud settles. The dust then accumulates in layers on the equipment and the workshop floor. Depending on the heat of the equipment, or the chemical composition of the particles, this mass of dust can produce self-heating or pyrolysis, leading to fire or explosion. <\/p>\n\n

Theappearance of these phenomena<\/strong> requires specific conditions, which we summarize below (for more information, see the detailed ATEX articles).<\/p>\n\n

How does dust self-heat, and what are the consequences?<\/h3>\n\n

The particular chemical composition<\/strong> of some dust deposits can trigger a spontaneous exothermic chemical reaction. And deposition conditions can induce heat generation faster than its dissipation into the ambient air. The temperature of the dust layer then rises, without any external heat being added to the reaction system. It’s self-heating. Higher temperatures accelerate the rate of reaction, which in turn accelerates the increase in heat. Initially slow to heat up, it can progress to incandescence or self-ignition<\/strong>. Depending on local environmental conditions (presence of materials sensitive to heat flux, presence of a cloud of combustible dust, etc.), the reaction can lead to fire or explosion. The self-heating phenomenon is therefore preliminary to fire and explosion.<\/p>\n\n

How does dust pyrolysis work, and what are the consequences?<\/h3>\n\n

Pyrolysis refers to the chemical decomposition of an organic product<\/strong> under the influence of high heat, and in the presence of a poor or oxygen-free atmosphere. <\/p>\n\n

Theself-heating of a dust deposit<\/strong>, or the heat flow from a hot surface on which the dust deposit is located, can produce pyrolysis gases in the low-oxygen or non-oxygenated part of the deposit. <\/p>\n\n

These gases can accumulate in the atmosphere. Thethermal energy<\/strong> that triggered pyrolysis, or another energy source, can ignite these gases. Depending on their concentration, ignition will produce a fire or an explosion. Like self-heating, dust pyrolysis is a precursor to fire or explosion.<\/p>\n\n

What are the conditions for a dust fire?<\/h3>\n\n

A dust fire<\/strong> is caused by the combustion of combustible gases released by the decomposition of dust during pyrolysis. Fire starts when three elements are present in sufficient quantity: fuel (gas), oxidizer (oxygen in the air), and activation energy (heat, spark, external flame…). The gradual diffusion of combustible gases, then their mixing with air, feeds the fire’s flame. The flame generates toxic fumes and a heat flow that sustains the spread of the fire. Heat flux radiation <\/strong>can cause pressure vessels or other combustible materials to explode. <\/p>\n\n

What are the conditions for a dust explosion?<\/h3>\n\n

An explosion is the instantaneous combustion<\/strong>, releasing intense energy, of an explosive atmosphere (ATEX). This is accompanied by a dramatic increase in the volume, temperature and pressure of ATEX gases.<\/p>\n\n

There are six conditions under which a dust explosion can occur. Three of these are the same as those causing the fire: the simultaneous presence of air, dust and a source of ignition<\/strong>. Three factors accelerate the combustion reaction: particle size fineness, enabling dust to be homogeneously suspended in the air; dust concentration in the air reaching the explosive range; and sufficient confinement for pressure to act as a combustion gas pedal. <\/p>\n\n

ATEX dust is formed in operating rooms and equipment. The thermal and pressure effects generated<\/strong> by the explosion threaten the working environment and personal safety.<\/p>\n\n

\"explosion<\/figure>\n\n

What’s the difference between a dust fire and a dust explosion?<\/h3>\n\n

The context in which an explosion is triggered differs<\/strong> from that of a fire, even if each phenomenon can lead to the other. <\/p>\n\n

In an explosion, the mixture of combustible dust and air is pre-existing. The premixed flame propagates on its own, forming a combustion wave. <\/p>\n\n

In a fire, dust provides the fuel in the form of gas through pyrolysis. It’s the pyrolysis gas\/air mixture that ignites. And the diffusion flame is maintained as long as the dust feeds it. <\/p>\n\n

As the reagents are premixed in an explosion, its energy yield is far greater than that of a fire<\/strong>. In a fire, the speed at which combustible gases diffuse through the dust and mix with the air determines the kinetics of the phenomenon, which is much slower than in an explosion.<\/p>\n\n

Overview of regulations applicable to fires and dust explosions.<\/h2>\n\n

Explosions and fires<\/strong> caused by dust have an impact on employee safety and destroy equipment on the operating site, with potential consequences for the environment. Consequently, the French Labor Code and Environmental Code provide a framework for the prevention of these phenomena. Often it’s a matter of transposing European law. Theemployer must ensure that premises<\/strong>, prevention and protection systems comply with regulations.<\/p>\n\n

With regard to fire, the French Labor Code regulates the configuration of premises (implementation of means of evacuation) and the protection of workers (installation of alarms and fire extinguishers, etc.).<\/p>\n\n

With regard to explosions, the French Labor Code requires employers to assess the risks associated with ATEX (Explosive Atmospheres), and to take specific measures to ensure the prevention, safety and protection of workers in the event of an explosion. It covers <\/p>\n\n