Suction of combustible and explosive dust
The topic of combustible dusts in the workplace is of paramount importance for worker safety and accident prevention. This article will review the characteristics of combustible dusts, how to prevent explosions, and how to identify and control the explosion potential of dusts.
HOW TO CHOOSE THE RIGHT INDUSTRIAL VACUUM CLEANER
In presence of combustible dust, the choice of the correct Atex or ACD certified Industrial Vacuum Cleaner depends on the work area (whether or not it requires Atex certification) and the type of dust to be removed. Depureco has developed safe solutions for all kinds of work situations.
ACD CLASSIFIED VACUUM CLEANERS
ACD vacuum cleaners, designed and manufactured according to IEC 60335-2-69:2021, safely collect combustible dust when ATEX certification is not required. Ideal for small bakeries or companies handling materials such as flour, wheat, sugar, lactose and the like, they offer a safe solution in unclassified areas.
ATEX CERTIFIED VACUUM CLEANERS
Atex industrial vacuum cleaners, designed and manufactured according to the latest UNI EN 17348:2022 safety standards, enable the vacuuming of even combustible dust within areas requiring certified equipment, in accordance with EU Directive 2014/34.
Product selection guide
Combustible dusts in ordinary areas (not classified Atex)
ACD Vacuum
Combustible dusts in Atex zones with vacuum cleaner in ordinary zone (not classified as Atex)
ACD Vacuum
Combustible or non-combustible dusts in Atex zones
ATEX vacuum
How is a dust explosion triggered?
Combustible dust explosion is triggered when all factors of the explosion pentagon are present simultaneously: combustible, oxygen, ignition source, fuel dispersion and confinement. To avoid accidental explosions, it is essential to take proper precautions in handling, storing and processing combustible materials.
Combustible is a substance that can burn and react with oxygen, generating energy. Combustible dusts are fine, dry particles that can burn rapidly when exposed to the ignition source. Oxygen is a gas that fuels the combustion of the fuel, increasing the temperature and pressure within the system.
The ignition source can be an external energy, such as a spark or flame, that comes into contact with the combustible dust. Once combustion begins, the dust particles heat up, producing hot gases and expanding rapidly. This combustion process is known as deflagration.
Fuel dispersion is another important factor in triggering the explosion. When combustible dust particles are dispersed in the air, a mixture of fuel and oxygen is created that can be easily ignited by the ignition source.
The confinement of the fuel-oxygen mixture is a critical factor that can amplify the effect of the explosion. When the mixture is confined in a confined space, such as a combustion chamber, the pressure and temperature increase rapidly due to combustion. This pressure increase can cause the chamber to explode, generating a violent shock wave that can cause significant damage to people and surrounding property.
Types of combustible dust and their hazards
Combustible dusts pose a potential safety hazard in many industries. There are three main categories of flammable dusts: natural organic materials, synthetic organic materials and metals. Each category has different behavior when exposed to a source of combustion and therefore requires specific management to ensure a safe working environment.
The natural organic materials category includes substances such as flour, wood, paper, natural fibers and food products. These materials consist mainly of carbon, hydrogen and oxygen, and can be easily combusted in the presence of a heat source, such as a spark or an open flame. Combustion of these materials also produces toxic fumes and gases, such as carbon monoxide and hydrogen cyanide, which can pose additional health hazards to workers.
Synthetic organic materials are chemicals of synthetic origin, such as polymers and resins, that are used in many industries, such as plastic and rubber production. These materials can be highly flammable and can produce toxic fumes and gases when burned. They can also be very sensitive to sparks and heat sources, such as welding lights or machines that produce friction, and therefore require careful handling to prevent fires and explosions.
The category of metal powders includes substances such as aluminum, magnesium, titanium and zinc. These materials can be highly flammable and can react violently with water and other chemicals, such as acids. Burning metals can also produce toxic fumes and gases, such as carbon monoxide and zinc oxide, which can pose additional health hazards to workers.
How to identify and control dust explosion potential
Knowing the parameters of treated powders is essential to eliminate ignition sources and limit the effects of explosions, minimizing injuries.
Here are some indices for assessing the hazardousness of combustible dusts:
- KST: measures how destructive a given powder is once the explosion starts
- St: indicates the explosive class, i.e., the explosive power in case of initiation
- Pmax: allows calculation of how much damage the powder is capable of doing within an enclosed environment
- MIE: indicates the amount of energy required to ignite the dust explosion
- MIT: indicates the minimum temperature for which a hot surface will trigger a dust cloud or dust layer after making contact.
Equipment such as industrial vacuum cleaners, machinery, and processing equipment that come into contact with combustible dust must be designed to prevent leakage and minimize the release of dust into work areas while ensuring maximum safety.
KST and St in particular give an indication of the general hazard of a possible explosion resulting from combustible dust.
| Dust explosion class | Kst [bar⋅m/s] with 10 kJ initiation | Type of explosion |
|---|---|---|
| St 0 | 0 | None |
| St 1 | >0-200 | Weak |
| St 2 | >200-300 | Strong |
| St 3 | >300 | Very Strong |
In conclusion, the presence of combustible dust in a work environment should not be underestimated, as it poses a great risk to workers and the entire work environment. Contact us to find out the most effective and safe method of controlling your combustible dusts.