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Home / Blog / Flour Dust: Sources, Description and Properties, Hazards, Aspiration and Filters, Equipment Selection

Flour Dust: Sources, Description and Properties, Hazards, Aspiration and Filters, Equipment Selection

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Flour dust poses a risk to both the environment and human health. For this reason, facilities involved in the production of baked goods or processes such as grain crushing, sieving, grinding, and milling must utilize specialized equipment. Agricultural industry facilities should be equipped with aspiration systems. Excess heat, moisture, and dust are all critical factors that need to be considered when designing equipment.

Sources

Working with flour dust is generated from the primary raw material used in the production of baked goods. During the transportation and handling of grain, as well as at flour mills during the packaging operation, powder is dispersed.

If the production equipment is highly sealed and feed lines are well covered, dusting is almost eliminated. However, this effect may still be observed in areas where dough mixing and preparation for baking occur.

In addition, contributors to airborne particles in a bakery setting include: sifting operations and certain dough mixing machines. Contaminants are also present in biscuit and confectionery production, as well as in bread factories.

Grimy areas include rooms where:
  • Flour is stored in containers or distributed in bags with pneumatic bag receivers.
  • A bag discharging machine is installed, and sifting and weighing of raw materials are carried out.
  • Dump pits are in place.

Description and Properties

Flour dust is classified as a complex organic pollutant consisting of particles from ground grains such as wheat, rye, barley, or corn, obtained through meticulous milling. It has a finer particle size than the original material and becomes airborne when the grains are finely ground into powder. This substance has the following distinct properties:
  • Flour combustible dust is explosive, with a minimum explosible concentration (MEC) of 10.1 g/m³.
  • It is non-toxic.
  • It has a higher level of dispersion compared to grain dust.
  • The workplace exposure limit for flour dust ranges from 0.5 to 10 mg/m³ (OEL).
  • The particle size ranges from 1-240 µm, with approximately half particles varying between 50-40 µm.

Danger and Health Impact

Exposure to flour dust in the occupational environment, when combined with air currents and reaching certain concentration levels, poses a serious risk as it can transform into an explosive mixture.

Additionally, the health effects of flour dust include harm to human health. It can cause both acute and chronic irritation of mucous membranes. More specifically, it can contribute to the development of asthma, severe allergic reactions, and pneumoconiosis, all of which can lead to significant health consequences.

Respiratory diseases such as chronic bronchitis and emphysema can result from inhaling airborne particles. Additionally, these contaminants can lead to allergic sensitization, increasing the risk of developing allergic reactions and bronchial asthma. They may also contain allergens like beetles, moths, and weevils found in flour. Mechanical injury to the eyes can occur, and irritant effects may lead to conditions such as conjunctivitis and dermatitis.
Flour Dust
Flour Dust
Particles inhaled with air can settle on teeth, become part of dental plaque, and expose them to microorganisms, contributing to tooth decay. Furthermore, particles entering the mouth are acted upon by saliva amylase, which over time can deplete the salivary glands, disrupt normal physiological processes for oral mucosa cleansing, and reduce resistance to various diseases.
Flour dust is particularly dangerous because it settles on surfaces such as production equipment and floors, especially when regular cleaning is lacking, causing excessive accumulation. In the event of a "localized" dust deflagration, all settled particulate matter can become airborne, potentially triggering an explosion with sufficient force to destroy an entire building. The level of explosion risk is directly related to factors such as the dust concentration, dispersion, amount of volatile substances, and ash content. The heat of combustion is approximately 18,000 kJ/kg-1.
Explosion at Cargill Plant, December 1977, USA
Explosion at Cargill Plant, December 1977, USA

Aspiration

Aspiration is achieved through the use of the following systems, which prevent flour dust explosion and ensure air purification. The most effective types are: baghouse filters and cartridge dust collectors.

The technical specifications and operational properties of the aspiration system will directly depend on the configuration and design. Each system is tailored to the specific requirements of the customer, and manufacturing is carried out according to a custom design. All parameters are calculated based on the technical specifications and project requirements, adhering to established standards.
BLIZZARD Bag Filter
BLIZZARD Bag Filter

Baghouse Filters

Baghouses operate on the principle of dry filtration. Contaminated air is drawn into the system and passes through fabric filter elements, known as bags. Pollutants are trapped on the surface of the filters, and the cleaned air is either returned to the room or released into the atmosphere.
Advantages of a baghouse flour dust collector for aspiration include:
  • Reliability
  • Long service life
  • Ease of operation and maintenance
  • High performance
  • High efficiency, regardless of the permissible dust concentration in the work area
  • Resistance to high pressure
  • Stable hydraulic resistance
The flour dust collection systems will remain effective even when handling high concentrations of particulate matter.

Cartridge Filters

Cartridge filters operate on a similar principle to baghouse filters but use cylindrical cartridge filter elements made from specialized materials such as pleated paper, synthetic materials, or non-woven fibers. Contaminated air passes through the cartridges, where contaminants are captured on the external surface. The cleaned air is then either returned to the room or expelled outside.

Models designed for flammable flour dust collection, such as the AKMAN, are suitable for handling this type of material. These are classic filter designs intended for gas purification. AKMAN filters are known for their reliability and low maintenance.
AKMAN and FOEHN by TORCH-AIR
The working principle is straightforward:
  1. Air flows into the filter equipment through a dedicated air duct.
  2. Contaminants settle on the surface of the pleated cartridge.
  3. Clean air passes through the cartridge into the clean air chamber.
  4. A fan at the outlet draws the air outside or back into the room.
AKMAN filters handle contaminant levels effectively, regardless of the concentration. The design is meticulously engineered, featuring compact dimensions and modern, efficient filtering materials.

Another model, the FOEHN cartridge filter, captures contaminants in the work area and is highly regarded for its benefits, including:
  • Ease of operation
  • Quick-release covers for easy access to internal components
  • Compact size, allowing placement in production facilities without compromising effectiveness
  • High power, which is 25% greater than similar models
  • High cost-efficiency
  • Long service life due to the unique cylindrical cartridge design
The FOEHN flour milling dust collector utilizes a pleated cylindrical filter element. Its compact structure means that one unit measures only 12.8 inches in width and 39.5 inches in height, with a filter surface area of 178 square feet.

Unsure which filter to choose: baghouse or cartridge? Learn more about the differences between the systems in this article.

Measures

To more effectively control, the following flour dust control measures can be implemented:
  1. Baghouses are highly effective for capturing airborne particles and reducing their concentration in production areas. Alternative options, such as cartridge filters and cyclones, can be used for pre-cleaning the air. Additionally, flour filling dust collection systems are designed to efficiently capture particles generated during the filling process, contributing to a safer work environment.
  2. Local Exhaust Ventilation (LEV) systems are installed near sources of airborne contaminants, such as loading, unloading, and processing areas, to capture and direct contaminated air to filtration devices. Central Ventilation Systems provide overall air exchange in the facility, improving air quality throughout the work area.
  3. Implementing an automated dust collector for flour mills helps minimize powder exposure to open air and workers, significantly reducing contaminants. Closed conveyors and enclosed transport systems are also employed to minimize airborne particulate dispersion.
  4. Regular wet cleaning of floors and surfaces prevents the accumulation of particles and reduces the risk of explosions. HEPA vacuum cleaners are also used to clean work areas effectively, preventing recontamination of the air.
  5. Workers should use PPE such as respirators and masks. Educating workers on safe working practices reduces health risks and prevents accidents.
  6. Keeping the room at an optimal humidity level helps reduce particle dispersion, as moist powder is less prone to airborne particle formation.
These measures, when combined, help control pollution, improve working conditions, and reduce health risks for employees.

Equipment Selection

To mitigate flour dust hazards, careful selection of air cleaning equipment is essential. The necessary data for selecting air filtration systems include:
  • Airflow volume (CFM) and the temperature of the stream entering the system.
  • Bulk density (g/m³).
  • Operating temperatures of the gases and particulates.
  • Properties of pollutants, such as stickiness, abrasiveness, and flammability.
  • Continuous or intermittent operation of the equipment.
  • Filter regeneration preferences, such as reverse air cleaning, compressed air cleaning, or mechanical shaking.
Torch-Air provides warranties on all products under favorable conditions outlined in the warranty certificate. Free maintenance is available if a factory defect is found or if replacement of expired consumables is needed.

  • Delivery is expedited with shipping methods chosen based on the weight and size of the equipment in consultation with the client.
  • Free Consultation: Available for all questions related to filtration.
  • Certified Equipment: Only certified equipment is offered, with certificates provided after thorough testing.
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Head of Engineering,
Vladimir Nikulin
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